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THE 
 
 FOULING AND COEEOiJjaN. 
 
 IRON SHIPS: 
 
 CAUSES AND MEANS OF PREVENTION, 
 
 THE MODE OF APPLICATION TO THE EXISTING 
 lEON-CLADS. 
 
 BT •;cX 
 
 CHARLES F. T. YOUNG, C.E., 
 
 MKM. SOC. ENGINEERS, ASSOC. I.N.A. 
 ADTHOE or 
 
 'the economy or steam poweu on common eoads;" "the best mode of 
 
 PKOTECTING LONDON EBOM THE KAVAGES OP FIEE;" "FIRES, FJEE 
 ENGINES, AND FIRE BRIGADES," ETC. 
 
 lit^ HInstratxoitB. 
 
 LONDON : 
 
 THE LONDON DRAWING ASSOCIATION, 
 7, DUKE STREET, ADELPHI, W.O. 
 
 1867. 
 
 [^The Sight of Translation is Heserved,"] 
 
"That which is perfectly obvious to any man of common sense, so soon as it is mentioned, may,' 
 nevertheless, fail to occur even to men of considerable ingenuity." — Wliately 
 
THE EIGHT HONORABLE 
 
 SIE, JOHN PAKINGTON, Bart., G.C.B., D.C.L., M.P., 
 
 PRESIDENT OJ? THE INSTITUTION OP NAVAL ARCHITECTS, 
 
 FIRST LORD OP THE ADMIRALTY, 
 
 GREAT BRITAIN IS INDEBTED 
 
 IRON-CLAD FLEET, 
 
 THIS WOKK IS INSCBIBED, 
 
 HIS MOST OBEDIENT SERVANT, 
 
 -THE AUTHOR. 
 
PREFACE. 
 
 The continued want of success which has hitherto attended all 
 the attempts^ which have been brought to a practical test, for pre- 
 venting the fouling and corrosion of iron ships, and the many cases 
 of fouling and corrosion which have come under the Author's notice, 
 induced him to turn his attention to the question, with the view, if 
 possible, of detecting the cause of failure. 
 
 In the course of his researches he collected a great amount of 
 facts and particulars, and the serious and increasing magnitude of 
 the evil became so striking that he resolved to embody them with 
 some remarks and statements on ships of wood and iron, with the 
 view of directing public attention to so momentous a subject, and 
 pointing out a ready and practical means by which these evils can 
 be removed. 
 
 At the present moment the prevention of fouling and corrosion 
 in iron ships and vessels is still held to be unaccomplished, and the 
 magnitude of the evil, as a whole, is comparatively unattended to, 
 its existence being only occasionally recorded in the naval intelli- 
 gence of the daily papers, or brought under the notice of the 
 members of scientific institutions. 
 
 It being generally considered needful that, when statements are 
 made or opinions advanced, proofs in support of them should be 
 adduced, sufficient well authenticated examples are given out of an 
 immense number which have been collected ; and the opinions of 
 most of those who have experimented upon or gone into the 
 questions involved in the two points of corrosion and fouling are 
 
VI PREFACE. 
 
 brought forward to corroborate the statements and opinions of the 
 Author. 
 
 The plan by which the fouling and corrosion of iron ships are 
 preventedj and which has been brought forward by Mr. T. B. Daft, 
 C.E., is in all respects the soundest, simplest, and most practical, 
 and, from being arranged in accordance with the known laws of 
 nature, most certain of success. On these grounds the Author gives 
 it his best support, and has endeavoured to prove that it is in all 
 respects capable of fulfilling the requirements sought to be obtained. 
 It is believed that this will be amply shown to all who have given 
 any attention to the subject. 
 
 C. V. T. Y. 
 
 7, Duke Stebbt, Adblphi, 
 
 London ; March, 1867. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 WOOD. 
 
 Wood the earliest known Material employed in the Construction of 
 Boats, &c. — Its Disadvantage in Shipbuilding — ^Difficulty of obtain- 
 ing suitable Timber for Building Wooden Ships. — Absorption of 
 Water by — Their Comparative Cost of Construction and Main- 
 tenance— " Composite " Ships — Effects of the Working of Machinery 
 in Wooden Ships — Iron-plated Wooden Ships, their Costliness and 
 Non-durability page 1 
 
 CHAPTER II. 
 
 IBON. 
 
 Iron, as a Material for the Construction of Ships, &c., a Modem 
 Device — Its Defects in Shipbuilding — Its Advantages — Objections 
 to Employment of — Answers to same— Cost of Construction of 
 Iron Ships of War — Impossibility of Constructing Ships of size of 
 " Great Eastern," &c., of any other Material than Iron 12 
 
 CHAPTER III. 
 
 CHEONOLOGT OP lEON SHIPS. 
 
 First Record of Iron-built Yessel — List of some of earliest Vessels 
 Constructed of Iron — The " Great Britain " and " Great Eastern " — ■ 
 The " Warrior " and other Iron Men-of-War — Committee of Lloyd's 
 Register, their Classification of Iron Ships 25 
 
 CHAPTER IT. 
 
 SHEATHING. 
 
 List of Materials employed for— Archimedes' Ship— Sheathing in the 
 reigns of Henry VIII and Charles II — Various Patents for — Mr. 
 Dafls' Plan for— Sir Humphrey Davy's "Protectors" — Action of 
 Sea-water on Copper or Metal Sheathing— Supposed " Poisoning " 
 Process of Copper Bottoms— Effects of Copper Sheathing on Iron 
 Ships— Different Plans for Sheathing Iron Ships 33 
 
Vlll 
 
 CONTENTS. 
 CHAPTER V. 
 
 FOULING. 
 
 Effects of EoTilmg on Ship's Speed— Great Loss experienced by Eouling 
 of Ships' Bottoms— Various Mixtures employed to Prevent— De- 
 siderata in Iron Ships PAGE 50 
 
 CHAPTER VI. 
 
 COEBOSION. 
 
 Evil Effects of Corrosion on Iron Ships — Causes of— Examples of 
 Damage done to Iron Ships by— Galvanic Action set up on Ships' 
 Bottoms — by Contact of Copper with Iron — Various Measures 
 adopted to Prevent G-alvanic Action on Iron Ships— Difficulty of 
 Preventing — Different Authorities on — Zinc the only Metal appli- 
 cable in Contact with Bottoms of Iron Ships 81 
 
 CHAPTER VII. 
 
 IMPEOVBD CONSTBrCTION. 
 
 Mr. Daft's Plan of — " In-and-out " Strake System — " Butt " versus 
 "Lap " Joint — Illustrations of Compressed Teak Caulking — ^Advan- 
 tages of Zinc Sheathing — Estimate of Saving effected by adoption of 
 Mr. Daft's Plan of Sheathing — Other Advantages obtained by 102 
 
 APPENDIX. 
 
 Extracts from various Papers on the Construction of Iron Ships, their 
 Fouling and Corrosion, and on their Preservation — Mr. Daft's Plan 
 of Construction — Papers read before the British Association at 
 Nottingham, " On Zinc Sheathing for Iron Ships ;" and at the Society 
 of Arts, " On the Construction of Iron Ships," &c., by S. J. Mackib, 
 Esq., with Discussion thereon — The latest Results of PouUng, and 
 the Progress of Improved Construction 141 
 
 CORRIGENDUM. 
 
 Page 81, line 11 from bottom, /or " iron " read " some." 
 
 Directions to the Binder. 
 
 Frontispiece, to face Title-page. 
 
 Sheet of Government Experimental Plates, to face page 128. 
 
 The TUustrations are hy the London Drawing Association. 
 
THE FOULING AND COEROSION 
 
 IRON SHIPS. 
 
 CHAPTER I. 
 
 WOOD. 
 
 Wood, so far as history shows us, seems to have been the earliest 
 material employed in the construction of boats or floating bodies, 
 to carry or support anything on the water ; and this, from its less 
 specific gravity than water, and its almost universal distribution on 
 the face of the globe, together with the comparative ease and readi- 
 ness with which it could be worked and put together, render it 
 well suited for the purpose ; consequently, its employment for ships 
 or boats may be called universal. Popular prejudice, from its long 
 use, is strongly enlisted in its favour, and this has contributed 
 most powerfully to keep it in use during the past five-and-twenty 
 years, in many cases where its employment is a disadvantage rather 
 than otherwise. 
 
 Whatever advantages it may possess as a material for the con- 
 struction of boats or ships, from its less specific gravity, the ease 
 with which it can be worked and put together, and its general dis- 
 tribution over the surface of the globe, are in the present day of 
 large ships and powerful engines more than counterbalanced by the 
 following disadvantages, which it is well known and generally ad- 
 mitted to possess, and these may be classed as follows : — 
 
 First, the supply is decreasing; next, great diflBculty exists in 
 obtaining it of the dimensions now required ; next, its great bulk 
 in proportion to its strength ; next, the great difficulty if not im- 
 possibility of building very large ships of proper strength ; next, its 
 great size in proportion to its weight ; next, its want of uniform 
 strength ; next, its want of durability ; next, its liability to dry rot, 
 the ravages of the worm, and damage from the sun and water ; 
 
 1 
 
2 THE FOULING AND CORROSION 
 
 next, its inflammability; next, it increases in weight as the ship 
 gets older; next, the great difficulty of fastening it securely 
 together ; and lastly, its want of durability under any circumstances. 
 Where expedition in constructing wooden ships is required, there 
 durability has to be sacrificed, and of this examples without end are 
 not wanting. 
 
 To obtain durability in wooden structures it is most important 
 that the wood should be thoroughly seasoned, and this can only be 
 obtained by keeping it under those conditions most favorable for 
 this purpose, and giving it sufficient time to become freed from the 
 sap and juices contained in it. 
 
 It also should be felled at that season of the year when the sap is 
 down, and the tree as it were torpid, for if it be cut in the spring, 
 when the sap and juices have begun to move or circulate, the value 
 and durability are both most seriously compromised if not destroyed. 
 In tropical countries it has been found that timber felled when 
 the moon is on the increase becomes shaky, and its durability 
 seems to have left it; and there can be no doubt that a similar 
 influence, though possibly in a less degree, exists in countries north 
 and south of the tropics on timber felled at that period. 
 
 The delays that have occurred in the construction of the large 
 wooden ships of war which have been built of late years, from' the 
 difficulty of obtaining timber of the required scantling, and particu- 
 larly of the necessary forms, are well known ; and the increasing 
 difficulty of meeting with a sufficient supply of home-grown timber 
 has been a frequent cause of complaint. Of late years oak and 
 other foreign timbers, have been largely employed in the con- 
 struction of wooden vessels, but it seems that the advantages gained 
 by their erhployment are considered very questionable, and they are 
 generally admitted to be very inferior to home-grown timber as 
 formerly obtainable. 
 
 During the late Russian war, from having no stock of ships to 
 use, great exertions were made to have such ships as were required 
 built ; but the great scarcity of seasoned timber necessitated the 
 employment of inferior material ; and what with inefficient inspec- 
 tion, unsettled action, hurried work, and alterations during con- 
 struction, there resulted a costly expenditure with most unsatis- 
 factory returns on the outlay ; a little of which may be learned by 
 perusing the Report on the Gunboats published in 1860, as the 
 result of an inquiry by a Parliamentary Committee. 
 
 Mr. Corry, when Secretary to the Admiralty in 1846, admitted 
 that "by far the largest portion of the timber used in the con- 
 struction of ships is of foreign growth ; and it is therefore a mate- 
 rial point if iron, which is easily procured in this country, can be 
 safely applied to the building of ships of war; and secondly, if 
 there were a sudden demand for an increase of our naval force as 
 
OF IRON SHIPS. 3 
 
 there was when the well-known 'Forty Thieves' were built at 
 once, it would be totally impossible, either in our public dock- 
 yards or in the ship-yards of private builders, to find a sufficient 
 quantity of seasoned timber, and the necessary consequence would 
 be a premature decay of those built of timber unfit for use." 
 
 The readers of this will remember how exactly all this came to 
 pass during the late war with Russia. 
 
 Wooden ships gradually absorb the water in which they float, 
 becoming sodden or watersoaked, as it is termed, which adds per- 
 ceptibly to their weight, decreases the speed of the ship and the 
 durability of the material, and sets up chemical action in the 
 metals used in her construction, whereby their holding powers are 
 diminished and the tendency of working amongst the pieces 
 forming the hull greatly increased, both of which are slow though 
 certain causes of destruction. 
 
 In ' Engineering ' of August 9, 1866, it is stated that " a 600 
 ton wooden ship, after being three years afloat, will absorb by 
 soakage from forty to sixty tons of water, increasing the draught 
 from six inches to nine inches, thereby increasing the positive 
 resistance and reducing the speed." 
 
 That a wood navy is not economical to maintain, in proportion 
 to the amount of service or duty obtained from it, is very generally 
 known and as generally admitted; but whatever disadvantages 
 belonged to it as a sailing navy, these have been enormously 
 increased since steam propulsion and armour-plating have been 
 introduced ; in fact, it may be said that the conditions required to 
 ensure the advantages of these two systems cannot be economically 
 or satisfactorily obtained 'by the employment of wooden hulls. 
 
 Mr. C. Seely, the member for Lincoln, who has endeavoured 
 to analyse the cost o'f our ships, stated in a speech at Lincoln, on 
 the 23rd January, 1867, that " the ' Frederick William ' had cost 
 ^6281,691 in repairing, when a similar vessel could have been built 
 for £134,453 \" 
 
 He also stated that he found " five vessels had cost £230,090 
 for repairs, which vessels could have been built for £152,148 \" 
 He further stated — "The Admiralty have never disputed my 
 figures with regard to the cost of ships, or if they have, they have 
 afterwards had to admit that I was correct." 
 
 He also found that in one yard alone the loss in converting the 
 timber used for shipbuilding amounted to £35,126, which was 
 more according to the Government authorities than it ought to 
 have done. 
 
 It was stated in the results of a Parliamentary Committee in 
 1848, that at fifteen years of age wooden ships of war require 
 "very considerable repairs," and that the average age at which 
 wooden ships are " broken up " is thirty-seven years ; but it does 
 
4 THE FOULING AND CORROSION 
 
 not tell us how often such vessels have been "rebuilt" in that 
 period. One thing, however, seems to have been overlooked in 
 this report, and that is, the average amount of work done by each 
 from the time of her launching to the time of being broken up, 
 from which some data might have been arrived at as to the 
 economy of wood ships for a given amount of duty at a given cost ; 
 and to this might then be added the additional cost at which these 
 ships had been maintained in a condition fit for service. 
 
 It would be an .interesting and valuable record, if a correct 
 return could be got of the cost of building and maintaining the 
 hulls of each wooden ship in Her Majesty's navy since, say 1845, 
 with the number of years' service each ship had given in return 
 for the outlay, so as to enable an average to be obtained of the 
 cost of wooden ships. A similar plan exists on railways with 
 regard to locomotives, by means of which the cost, maintenance, 
 mileage, and duty done by each are easily obtainable. 
 
 There can be no doubt that the results of such an investigation 
 would prove most astonishing and instructive, and afford some in- 
 sight into the causes of the vast expenditure which has been 
 incurred for a wooden fleet during the past five and twenty years ; 
 though it would, it is to be feared, fail to show a single justifica- 
 tion for the continued and exclusive employment of wood in place 
 of iron as a material for construction, which has so long been 
 suffered to exist, and which desire even at the present moment 
 seems as vigorous as ever. 
 
 The following statement of the cost of maintenance of some 
 wooden ships of war, which had all more or less been affected by 
 dry rot, will give some idea of the great expense entailed by the 
 employment of wood as a material for the construction of ships : 
 
 " Ardent " when new cost jg23,000 ; she was launched, but never 
 went to sea; at a later period she was found to require repairs 
 which involved the expenditure of no less than j617,000; soon 
 after this the decay was so rapid that she had to be broken up ! 
 
 '' Superb."— This ship cost £38,000 to build; after she had 
 been in service two years and a half she was found to require 
 repairs which cost no less than ^647,000 ! whilst the total amount 
 of service got from her only amounted to eleven years ! 
 
 " Achilles." — This ship cost £36,000 to build, was one year and 
 eight months in commission, when she was repaired at a cost of 
 £35,000, and in seven months more was paid off. 
 
 "Ajax."— This ship cost £39,000 to build; after five months' 
 service she was repaired at a cost of £36,000, her entire service 
 being four years. 
 
 " Spencer."— This ship cost £36,000 to build, her repairs 
 amounted to £43,000, and her service to two years, when she was 
 paid off. 
 
OF IRON SHIPS. 5 
 
 Taking, then, the services of the vessels in return for the outlay, 
 we find that in the case of the " Ardent " no return was had in 
 the shape of service ; consequently, £40,000 were entirely thrown 
 away ! 
 
 The " Superb " gave eleven years' service on an outlay of 
 £80,000, representing £7272 14s. Q^d. per annum. 
 
 The ''Achilles" gave two and a quarter years' service on an 
 outlay of £61,000, representing £27,111 2s. 2\d. per annum. 
 
 The " Ajax '' gave four years' service on an outlay of £65,000, 
 representing £16,250 per annum. 
 
 The " Spencer " gave two years' service on an outlay of £79,000, 
 representing £39,500 per annum ! 
 
 In 1812 the " Devonshire," 74, had her bottom planks cut from 
 the best kind of American white oak that could be procured ; but 
 although the ship had never been sent to sea, when examined in 
 1817, a period of five years, these planks were found to be totally 
 decayed. 
 
 The " Halifax," sloop-of-war, was built at Halifax, and launched 
 in October, 1806. The birch, red pine, and oak used in her con- 
 struction, were all grown in that neighbourhood ; but the vessel 
 was found unfit for service in January, 1812, at the end of the 
 short period of six years ! 
 
 The impossibility of combining the pieces forming the hull of 
 one of the large class screw frigates which have been built of late 
 years in such a way as to ensure strength and durability, when 
 wood is the material used, is admitted by many, and that none of 
 them, however carefully and scientifically constructed, could stand 
 for twenty-four hours the strain exerted by the engines when at 
 full power. Even the few hours occupied in a trial trip are found 
 to strain the after portions of the hull, causing the oakum used in 
 caulking the seams to start, and leakage to follow as a matter of 
 course, and this in spite of knees, riders, and straps, both of iron 
 and wood. 
 
 If, as is stated by Mr. Chatfield, of Her Majesty's Dockyard at 
 Devon port, the average durability of our sailing wooden men-of- 
 war, when employed in active service, is about thirteen years, when 
 built of oak, it would be an interesting piece of information to 
 know how long these same vessels would last if propelled by the 
 screw, and what the cost of their maintenance in proper and safe 
 sea-going order would amount to, if called on to perform in regular 
 work a similar amount of duty to that which can be obtained 
 from a well-constructed iron vessel of similar power and proportions. 
 
 So well known and admitted are the disadvantages of wood, 
 when used as the sole material for the construction of ships, that 
 many builders have taken up the plan of constructing what are 
 termed " composite" ships, or vessels with the frame or ribs made 
 
6 THE FOULING AND CORROSION 
 
 of angle or T-iron; covered with wooden planks ; and the success 
 which at the commencement has resulted from this mode of con- 
 struction seems to have led to its increase, and to vigorous exer^ 
 tions being made to cause its more extended adoption. 
 
 Now, in this case, the superiority of the results obtained over 
 what can be got by the use of wood alone, seems fully to prove 
 that the entire me of iron would give far more satisfactory 
 results; and that this must inevitably be the case is equally 
 certain, were it not that a serious evil, or rather two evils, are in- 
 troduced, namely, fouling and corrosion ; and that up to a very 
 recent period no means of preventing them, in a simple, easy, and 
 effectual manner, had been found, must be attributed the intro- 
 duction of the mixed or " composite" system of construction. 
 
 Dr. Pairbairn has well remarked that " wood- sheathing, when 
 attached to iron ribs, is, to say the least of it, a weak and unsatis- 
 factory construction. Composite structures of this kind, where 
 strength is required, are never safe, for the two materials are so 
 widely different in character as to produce, by their union, a source 
 of weakness of a most unsatisfactory description; and they are 
 therefore not to be compared with vessels framed exclusively of 
 iron, nor even with those entirely composed of wood. 
 
 " From the great difference which exists between the resisting 
 powers of iron and wood, it is evident that any combination, 
 however well executed, is not calculated to insure the requisite 
 strength for sea-going vessels subject to severe strains. On the 
 contrary, it appears obvious that a. vessel constructed with iron 
 frames, and covered with wood-sheathing, is a decidedly weak and 
 unsatisfactory structure. It is true that a vessel of this kind may 
 be strengthened by stringer plates and diagonal bracing; but to 
 do this is not to adopt the form the best calculated to give the re- 
 quired strength : it would be preferable and cheaper to make the 
 ship entirely of iron, and dispense with the wood-sheathing alto- 
 gether." He concludes by saying "that the system is not an 
 eligible one, and, for sea-going ships, is utterly at variance with 
 sound principles of construction ;" and he further says, " for large 
 ships intended to navigate the open sea, this construction cannot 
 be recommended, either oh the score of economy or safety." 
 
 The 'Times' of the 10th January, 1867, announced in the 
 " Naval and Military Intelligence," that seven new vessels are to 
 be built, four of which are to be " timber built, with iron deck- 
 beams and stringer plates ;" the three gunboats have these " great 
 features in the design and fitting, that they will be built with iron 
 frames, covered with an outer skin of two thicknesses of teak." 
 
 A few moments' reflection ought to show to any thinking, prac- 
 tical man, that if the weak material, wood, is strengthened by the 
 addition or employment of the stronger material, iron, as a com- 
 
OF IRON SHIPS. 7 
 
 ponent part of the structure, that the entire use of iron in place of 
 the confessedly weak material, wood, would not fail to be a more 
 certain and satisfactory mode of procedure, and the one most cal- 
 culated to ,give good results as regards safety, economy, and effi- 
 ciency. 
 
 In ' Engineering' for April, 1867, it is remarked that " the ob- 
 jection to composite ships is that they are not as cheap or as strong,, 
 with the same weight, or as tight, as iron ships ; but a still greater 
 objection lies in the difficulty of fixing the planks to the iron frames 
 by any expedient which will not involve corrosion by galvanic ac- 
 tion. If the wood is bolted to the iron by iron bolts, the coppering, 
 when applied, vrill quickly waste these iron bolts, so that they will 
 become unsafe ; whereas, if the attachment is made by means of 
 copper bolts, the bilge-water within the ship will cause the copper 
 nuts quickly to corrode the iron frame." 
 
 Mr. Scott Russell has well observed that "half of the entire 
 timber in a ship is merely occupied in strengthening the butts and 
 closing the joints of the other half} whereas the waste in an iron 
 ship will not be one tenth.'' Further on he says : " A large ship 
 built of wood is much weaker than a small ship built of wood. The 
 reason of this is that wood, being grown, the pieces of which it is 
 composed cannot be got proportionately larger as the ship is larger. 
 Thus, the planks of a small ship may be a foot wide and thirty 
 feet long; but planks for a ship three times the dimensions could 
 not be found three feet wide and ninety feet long ; and this holds 
 all through the ship : the bits of which it consists are a multitude 
 of small pieces, more multitudinous and smaller in proportion as 
 the ship is larger." 
 
 Admiral E. P. Halsted, in his ' Lectures on Iron-cased Ships,' 
 naming some of 600 to 1000-horse power, says, " I doubt if it can 
 be shown that any single frigate of the steam power I have named 
 has ever yet tested the ability of her frame to bear the stress of 
 her machinery at full work for any forty-eight consecutive hours, 
 perhaps not even for any twenty-four." 
 
 It has been remarked by a writer in ' Temple Bar* for 1860, and 
 who is generally believed to have been educated as a wooden 
 builder, that " the strain upon the wooden sternposts in some of 
 our fastest and finest ships, like the " Orlando" frigate, for ex- 
 ample, is so enormous, especially whenever the speed is forced at all, 
 that the whole fabric of the ship trembles and shakes to such a 
 degree that the vessel would soon be rendered unfit for service ; 
 even the topmost spars feel the shake in these vessels of very great 
 steam power. Therefore in modern naval warfare, as great steam 
 power — grande mtesse, as our neighbours have it — will be indis- 
 pensable, we must have iron sternposts, and no doubt also iron 
 ships. Nothing else will stand the tremendous strain of the screw ; 
 
8 THE FOULING AND COEROSION 
 
 and if ships of war are to be made shot-proof, the whole skeleton 
 of the ship must be of iron, as well as the muscles and skin. The 
 Emperor Napoleon, it will be found, has a little overreached him- 
 self, and perhaps hurried his able architect, M. de Lome, in con- 
 verting his ten good wooden ships into cuirassed frigates a grande 
 Vitesse. Shot-proof they may be, but they can never stand the 
 shake of the screw and remain weather-proof for anything like the 
 time that iron ships can." 
 
 Admiral E. P. Halsted stated at the Institution of Naval Archi- 
 tects, in 1864, that " the wooden flagship of the present admiral 
 commanding the Channel squadron, when lashed to the basin-walls 
 at Sheerness to take a first ' grind' out of her engines, was seen 
 with the oakum streaming from every seam in her quarters ; both 
 her rudder-posts rocking to every stroke of the engines ; the whole 
 ship trembling in the hands, as it were, of that rushing cylinder of 
 water ; while the master shipwright shouted with uplifted hands, 
 'For God's sake, stop those engines, or you'll drive the stern- 
 posts out of the ship !" 
 
 Mr. Scott Russell said, in 1864, at the Institution of Naval 
 Architects, "that bits of wood kept together with bits of metal 
 cannot stand the continuous day-after-day wear and tear of the 
 wriggle of a 1000-horse power screw in the tail of a ship. It is 
 not in the nature of the metal fastening of a wooden ship to sus- 
 tain that continuous wear and tear." 
 
 Mr. Grantham has remarked (Institution of Naval Architects, 
 1865), ''We have never found that the power of the screw could be 
 applied in a wooden ship without great, expensive, and massive 
 fastenings ; and as long as you have a ship planked, as wooden or 
 composite ships must be, they will be shaken by the excessive 
 action of the screw. We know that Government, with all their 
 appliances, have never yet been able to overcome this diflSculty, 
 and that when they have tried to work our wooden ships to their 
 full power, they have frequently been obliged to stop the engines, 
 owing to the excessive shaking in the afterpart of the vessel ; and 
 the result has been most serious. I come back, therefore, to the 
 conclusion that an iron ship is essential, and that the reason why 
 they are not universally adopted is their fouling." 
 
 Mr. W. B. Eobinson said, " I know that some of our ships in 
 the navy have been obliged to stop full steaming in consequence 
 of their sterns being too weak to bear the action of the screw." 
 
 The construction of wooden ships to be sheathed with thick and 
 heavy iron armour-plates is a great error, and it can only be justi- 
 fied by necessity, or where time would not admit of the construc- 
 tion of an iron ship. The argument that because there is a great 
 quantity of wood in store, and that it would be better to use it for 
 building ships to be cased with iron than to sell it, or that because 
 
OF IRON SHIPS. 9 
 
 wooden ships are partially or entirely built^ it is cheaper to case them, 
 cannot be justified for one moment on the score of econom,y, as it is 
 a certain fact, that the maintenance of such vessels is very costly, 
 and their durability — a most important point — is very problema- 
 tical. 
 
 It is very true that a wooden sea-going iron-clad is better than 
 no ship at all, if we take it on the question of being possessed of a 
 ship of any description ; but the most important part of the sub- 
 ject — that of having useful, serviceable, safe, economical, and effi- 
 cient vessels — seems to be quite overlooked in such arguments. 
 It is a serious question, whether it is not better to be without sea- 
 going vessels at all than to go to the great cost of building bad or 
 useless ones, fitting them out with expensive engines and arma- 
 ments, filling them with men, and sending them out to encounter, 
 possibly, a smaller one, but properly built, and perhaps in a few 
 moments being either knocked to pieces or sent to the bottom, 
 without having inflicted a proportionate amount of damage on her 
 opponent. In this case, it would be cheaper and better, either to 
 have had a proper ship or else to have had none at all. There 
 can be no doubt that the old saying, " The best is the cheapest," 
 applies with great force to this state of things. 
 
 The state of the "Prince Consort" after her cruise in the 
 November gale in 1863, will sufficiently show the disadvantages 
 of a wooden hull loaded with heavy iron plates, and its inability to 
 withstand such a storm as an iron hull equally loaded would do 
 with impunity. 
 
 The same argument will also apply to the case of building large 
 and untried experimental iron ships, into which are put expensive 
 engines, and armaments, together with skilled and trained crews, 
 which, without due tests, are sent away to teach us their deficiencies, 
 at more than probably the loss of the entire ships and men, from some 
 unknown or unprovided for contingency. Let us have experimental 
 construction, armaments, and engines, by all means ; but do not let 
 obstinate adherence to or undiscriminating prejudice for anti- 
 quated practice, prevent such fair unbiassed and thorough examina- 
 tion and tests, as will plainly show and certainly settle the 
 advantages or disadvantages belonging to each. 
 
 Mr. E. J. Reed, the chief constructor of the British Navy, in his 
 lecture on " Armour-plated Ships," which he gave at the Plymouth 
 Mechanics' Institute, on the 7th December, 1866, when speaking 
 of the existing wooden fleet, and converting them into iron-clads, 
 says — " These ships are all more or less decaying even now, and 
 by the time their conversion was completed they would be in a 
 worse condition of course. Again, they are not, as a rule, fast 
 ships even at present, certainly not equal to our first-class iron- 
 clads by a great deal. The proposal involves, however, the sink- 
 
10 THE FOULING AND CORROSION 
 
 ing of them much deeper in the water, and thus reducing even the 
 speed which they now possess. I have also made a rough estimate 
 of the cost of converting these ships upon this plan, and believe it 
 would amount to £140,000 per ship. And let us presume that 
 £130,000 would cover the cost (apd this is less than the cost of the 
 "Koyal Sovereign's" conversion, although she has armour that is not 
 now shell-proof, and has not been fitted with sea-going appliances), 
 and let us presume that twenty-five such ships are converted. 
 Then we shall have to expend three millions of money upon the 
 transformation of these old line-of-battle ships into comparatively 
 slow and inferior iron-clads, the whole of which together would be 
 unfit, I fear, to cope with one such ship as might be built for one 
 sixth of the cost, viz., a ship plated with fifteen to sixteen inches 
 of armour, carrying twenty-two guns, and steaming at a speed of 
 fifteen knots. It may be added that all these line-of-battle ships 
 have vreak and exposed sternposts and rudders, and are incapable 
 of being used securely as rams." 
 
 The Secretary of the American Navy in his last report, speaking 
 of wooden ships plated with heavy iron armour plates, says — 
 " Armoured vessels for ocean cruising must necessarily be of large 
 size, which cannot, . with the requisite strength, be secured in 
 -wooden structures. If attempted, the immense masses of timber 
 must rapidly decay, and the cost resulting from deterioration will 
 be such as no economical and prudent nation will consent to 
 sustain." 
 
 The 'Scientific American,' speaking of wooden armour-plated 
 ships, remarks — " It is undoubtedly the part of wisdom, in the case 
 of the English navy, to begin de novo. It is folly to suppose that 
 those wooden hulls, when razeed and loaded with iron of sufficient 
 protective thickness at and near the water line, and carrying 
 immense turrets, could withstand the assaults of thoroughly built 
 monitors. They were not constructed for such kind of warfare as 
 must be waged on the seas hereafter. Of how much service would 
 they be in such an encounter as that between the Austrian and 
 Italian fleets at Lissa ? Even the Re d'ltalia, immensely stronger 
 than any wooden ship could possibly be, could not stand' the shock 
 of ramming, although almost impenetrable to shot. There is a vast 
 difi'erence between wooden ships built for plating, and those built 
 for the old style of naval warfare. These last are not fit even for 
 harbour defence or floating batteries. Under the fire and direct 
 assault of true iron-clads, they would become the coffins of those 
 vpho put their trust in them." 
 
 The inefficiency of wood, and its weakness when used for the 
 construction of modern ships of war to be used as rams, was well 
 exemjJlified in the case of the " Amazon," which, whilst in the 
 Channel, ran foul of another ship, and with the other sank in a 
 
OF IRON SHIPS. 11 
 
 few minutes, from the effects of the shock ; the bows being wrenched 
 and the whole hull shaken. 
 
 It is believed that this vessel, for her size, was as strong as it is 
 possible to make a wooden ship, and as she was built and fitted 
 out with all the appliances which extended experience and the 
 highest scientific knowledge and skill could afford, it would seem 
 that this is correct. 
 
 Captain Cowper P. Coles, speaking at the Institution of Naval 
 Architects, in 1866, of the benefits to be derived from preventing the 
 fouling of iron ships, says — " It will also relieve us of the great difiB- 
 culty of building small iron cruisers to carry heavy guns for the 
 protection of our commerce in all parts of the globe, and eventually 
 admit of our relinquishing the expensive and wasteful system of 
 building these vessels of the inferior material vwod for the sake of 
 coppering them. I say wasteful advisedly, not because of the first 
 outlay in these wooden men-of-war, but because of their speedy 
 decay and constant need of repair, inherent to their weakness in 
 carrying heavy guns, or engines of high power, and I hope even- 
 tually to see iron cruisers of great speed, mounting one or two of the 
 heaviest guns, either wholly unprotected, or with a mere belt, and 
 the guns mounted on the central armament principle turret-wise. 
 With our vast possessions and trade we require numerous fast 
 cruisers, and we must always feel the enormous cost of our navy; 
 but in peace let us harbour and economise our resources not by 
 cheeseparing and shamming retrenchment, or cutting down our 
 navy, but by considering measures well before we adopt them, and 
 in building all men-of-war of matei'ial that may last for many years, 
 instead of wood, when we shall not see vessels annually sold out of 
 Her Majesty's navy "for a mere song'' to be broken up for fire- 
 wood, which even in their short lifetime have cost more than their 
 original value in repairs." 
 
 It is now perfectly evident that the requirements of the times 
 imperatively demand the employment of a better material than wood, 
 and although wood has held its place from it may be said " time 
 immemorial," it now appears that its use must be discontinued and 
 iron take its place. 
 
 Mr. A. M'Laine, in his paper read before the Institution of Naval 
 Architects in 1865, has remarked that "wooden ships of war may 
 perhaps with propriety be passed over without consideration, as a 
 complete anachronism in the present advanced position of naval 
 construction." And to this it may be added, that the " composite" 
 system of construction, in spite of its being so strongly advocated 
 as it is by many persons, should be placed in the same category, 
 as having less claim on our attention than ships constructed 
 entirely of wood. 
 
CHAPTER II. 
 
 IROjS^. 
 
 Iron, as a material for the construction of ships^ boats, &c., is, 
 comparatively speaking, a modern device, its use for this purpose 
 not being authenticated prior to the last twenty years of the past 
 century ; and although the results attained by its use were most 
 satisfactory, still prejudice, when added to some serious defects 
 which have hitherto been inseparable from its employment, has 
 successfully retarded its merits being appreciated, until a com- 
 paratively very recent period. 
 
 The great and hitherto unconquerable defects of iron, when 
 used for the construction of sea-going vessels, have been — ^its rapid 
 folding from barnacles, zoophytes, weed, &c., and the still more 
 fatal and dangerous one of corrosion, or the rapid and certain 
 destruction of the material of the vessel itself by the action of the 
 sea-water in which it floats. To these may further be added the 
 serious losses which have occurred from the employment of inferior 
 metal, an improper and ill-judged mode of putting it together, 
 and badly designed forms and plans for the vessels constructed 
 from it. All these, and the popular prejudice that "iron won^t 
 swim," and if it could, that it " wouldn't be safe," have con- 
 tributed enormously to retard the spread of iron as a material for 
 the construction of ships. 
 
 Against these defects and objections must be set the following 
 advantages, which are well known and admitted to exist : 
 
 First. — It is abundant, it is cheap, it is inexhaustible, it can be 
 easily manufactured, it has great strength, it has small bulk, does 
 not increase in weight by absorption, it is very durable, can be 
 combined so as to give the maximum of strength, can be securely 
 fastened, does not limit the size of ship that can be built, not 
 limited to form ; in short, it may be said that there are no knots, 
 no sap, no cutting across grain, no different strengths according to 
 position, no yielding, as in a wood ship. 
 
 It has been said that "iron has a thousand claims to our 
 suffrages, whilst wood has very few; and that in future ages. 
 
THE FOULING AND CORROSION OF IRON SHIPS. 13 
 
 wten wooden vessels will have ceased to hold any existence but in 
 the pages of the historian, mankind will begin to wonder at their 
 own temerity in having trusted their lives to such fragile and 
 precarious structures, as wooden ships will then appear to them 
 to be." 
 
 The strength and advantages of iron as a material for construc- 
 tion are well known and unquestioned. Dr. Fairbairn remarks 
 that "wrought iron, as a material for the construction of ships, 
 possesses advantages over every other kind of material. Besides 
 other advantages, it possesses great strength, durability, and light- 
 ness j it may be hammered into any requisite shape, and one piece 
 may be securely united to another by welding or by riveting, so 
 that comparatively small pieces may be so united and combined as 
 to form the strongest and most ponderous ship." 
 
 One iron top will wear out three bottoms, as was proved in 
 the case of the " Jamaica," of 421 tons, built at Glasgow ; the 
 " G. F. D.," built at Newcastle in 1849, and numerous other 
 cases. 
 
 In the introduction to Lloyd's Rules it is said that, " although 
 iron is about eight times heavier than oak, at the same time being 
 ten times stronger than oak, from the facility of uniting the parts 
 together by welding or riveting, a ship can be constructed of 
 greater general strength of iron than of oak, while it may be 
 lighter, thus having more displacement for carrying cargoes, and 
 if the surfaces be carefully preserved from corrosion, it can be kept 
 up in good condition at less expense than wooden vessels." 
 
 Iron, it is true, is not exposed to injury from the worm as wood 
 is, but it has its " dry rot," as it may be termed, in the shape of 
 rust and corrosion, which are further increased by the presence of 
 metals of a superior rank in galvanic power, when in a position to 
 cause this dangerous and fatal action to be set up. No hitherto 
 applied means have been successful in preventing this action, and 
 as the certainty of this action and its fatal eflFects become better 
 understood, there can be no doubt that such ill-judged attempts 
 will be abandoned, and wonder expressed that they should have 
 been for one moment thought of, proposed, or tolerated. 
 
 Mr. Holmes, in his 'Report on Steam Communication with 
 India,' says, "Iron ships are especially calculated for the vast 
 revolution in the navigation of the world which is at hand by steam- 
 vessels superseding every other navigation or mode of sailing. 
 Without iron ships this could never be, from the difficulty of 
 building very large ships of wood to draw little water, with a due 
 regard to those principles of naval architecture which are indis- 
 pensable in their structure ; and as far as relates to the strength, 
 flotation, and control of them, there is no limit. So great, indeed, 
 are the advantages of iron ships over those built of wood, that they 
 
14 THE FOULING AND CORROSION 
 
 only require to be known and understood to be universally adopted, 
 to the exclusion of all others." 
 
 The principal advantages possessed by iron ships over those of 
 timber are, greater strength than it is possible to attain by any 
 known combination of timber, less weight, greater available in- 
 ternal capacity, with the same external dimensions, greater speed 
 from diminished immersion, less cost of maintenance, and conse- 
 quently less time lost for necessary repairs. 
 
 Iron admits of every part being more securely and intimately 
 connected with each other than can possibly be done with wood, 
 added to which is the important advantage that either " with the 
 grain" or " across the grain," makes little or no difference in its 
 strength or applicability. 
 
 Dr. Pairbairn, in his 'Iron Shipbuilding,' remarks that "a 
 carefully riveted iron ship may be looked upon as jointless ; and 
 hence its value as a strong and durable structure. In short, an 
 iron ship, with its iron sheathing (plating) riveted to the frames, 
 may be considered as uniform in its powers of resistance, and su- 
 perior to anything yet accomplished by any other material with 
 which we are acquainted." 
 
 The rapidity with which iron can be worked up is one striking 
 point of superiority of iron over wood. Instead of requiring many 
 months, or perhaps years, to season in the timber-yard, having 
 previously taken may be centuries to grow, the ore may be con- 
 verted ready for shipbuilding in a few days, and in the course of a 
 few months more may be ploughing the waves, propelled by the 
 power of steam or that of a pleasant breeze. 
 
 Mr. Joseph H. Ritchie, one of the two principal surveyors of 
 Lloyd's, in speaking of iron as a material for the construction of 
 ships, says : " Although iron is about eight times heavier than 
 water, and ten times heavier than oak, at the same time, being ten 
 times stronger than oak from the facility of uniting the parts to- 
 gether by welding or riveting, a ship can be constructed of greater 
 general strength of iron than of oak, while it may be lighter ; thus 
 leaving more displacement for carrying cargoes; and if the sur- 
 faces be carefully preserved from corrosion, it can be kept up in 
 good condition at less expense than wooden vessels; hence the 
 rapid increase in their numbers, which in thirty years has placed 
 iron on a level with the material that had been used for shipbuild- 
 ing in all countries for four thousand years." 
 
 Dr. Fairbairn well remarks, in his ' Iron Shipbuilding,' when 
 speaking of the results obtained by the use of iron in the earlier 
 vessels, " The strength and sailing qualities of the whole of these 
 vessels were confirmatory of the great superiority of iron over 
 wood as a material for shipbuilding ; and we have only to refer to 
 the extensive use and enormous increase that have taken place in 
 
OF lUON SHIPS. 15 
 
 its application, not only in this country, but in every maritime 
 state of the globe, to be convinced of the soundness of the principle, 
 and the great superiority of the iron ship." 
 
 ^ When iron ships first came into use, every one almost prophe- 
 sied their failure, chiefly because it was metal, and not wood, that 
 was employed in their construction ; and there can be no doubt 
 that this prophecy was not a little strengthened, and its correctness 
 proved, by the incomplete mode in which many of such vessels were 
 constructed, and the want of due consideration of the strains to 
 which they were exposed, the result being the breaking in half 
 and foundering, if at sea, or the rapid breaking up of such as went 
 on shore or were exposed to the violence of such gales as they 
 might have encountered. 
 
 Mr. W. B. Adams, the well-known engineer, describes some of 
 the earlier attempts at iron ships as " large flat-bottomed wall- 
 sided open troughs of sheet-iron, rivetted together at the seams, 
 precisely like a long tank fitted with a wooden lid in the shape of 
 a deck. Form or proportion there was none, and the only framing 
 was the deck beams." 
 
 Unfortunately, even at the present time, experience does not 
 always show that such progress has been made in obviating known 
 evils as ought to have been and still requires to be made; and in 
 spite of the security professed to be obtained by " special surveys," 
 exact conformity with " regulations " and " rules,^' " classifica- 
 tion,^' &c., there have been constant proofs of their small utility, 
 and more of their glaring inefficiency, many notorious and well- 
 known examples being easily obtained if needed. 
 
 That sea-going ships of iron can be niade as safe, handy, and 
 useful as any wooden structure, and far more durable, cannot for a 
 moment be doubted^ and that wooden vessels can be, and are built 
 of quite as dangerous a character as theworst iron one,is also equally 
 true, but will not as a rule be so readily admitted. To say then 
 from these facts that one material is better than the other because 
 there have been some failures, but frorh their causes being known 
 admitting of an easy remedy, is simply absurd, and the whole 
 question turns upon which is the material most fitted for the re- 
 quirements of the times, and the conditions they have to fulfil. 
 The condition of the bows of the iron steam vessel which was 
 exhibited by the Motala Iron Works, in 1863, at the Interna- 
 tional Exhibition, and which at full speed had run right against a 
 perpendicular rock, will no doubt be remembered by many of the 
 readers of this, and is a good proof of the great strength of iron 
 ships when the proper quality of material is used. 
 
 The Controller of the Navy, in his celebrated statement relating 
 to the "Advantages of Iron and Wood in construction of Ships," 
 published in 1863^ remarks — " Great addition to the strength of 
 
16 THE FOULING AND CORROSION 
 
 the wooden structures is given by iron beams, iron decks, filling in 
 between the timbers, diagonal bracing, &c.j and taking all the 
 circumstances into consideration, it seems decidedly preferable at 
 the present time to build these ships in our dock-yards of wood, 
 rather than in private yards and of iron." 
 
 Now one would have thought that seeing the " great addition" 
 which is given to the strength of a wooden structure (in itself with- 
 out it a very weak and unsatisfactory production) by the use of iron, 
 it would have been self-evident that a ship constructed wholly of 
 iron, the material which gives a " great addition to the strength," 
 of a wooden hull, would have given far more satisfactory results 
 than the patched-up weak wooden one ; but this it seems the Con- 
 troller does not admit, although extended and extending experience 
 gives ample proof of the truth of it. 
 
 The Controller of the Navy, although preferring wood to iron, 
 admitted that " an iron ship can be built of larger dimensions than 
 a wooden ship, with no loss of strength." 
 
 That " an iron ship has more rigidity and strength of structure 
 as a whole than a wooden ship, though locally weak and liable to 
 be penetrated by blows which would fall harmlessly (?) on a 
 wooden ship." 
 
 That " an iron ship has much greater durability in certain parts 
 of the structure, indeed in all parts where the wood is in contact 
 with the iron, than a wooden ship ; and after a lapse of years the 
 iron frame would have sufifered next to nothing as compared with a 
 wooden ship." 
 
 Against these admitted advantages he urges the following dis- 
 advantages, as reasons why ships wholly of iron should not be 
 built, and if all of them could not be overcome, no doubt they 
 would be of serious moment : — 
 
 Krst, there is " the serious local weakness of the comparatively 
 thin plates of which the bottom of the ship is necessarily composed," 
 which gives rise to " the danger consequently of getting on rocks 
 in such ships." 
 
 Secondly, " The necessity which this weakness entails of con- 
 structing double bottoms, thwartship bulkheads, watertight com- 
 partments, sluice doors, &c., and various other complicated arrange- 
 ments which add both to the weight and cost of an iron ship." 
 
 Thirdly, '' The rapidity with which the bottom of an iron ship 
 gets foul, and the immense loss of all the ship's qualities that follows 
 from the adhesion of marine zoophytes. No practical remedy 
 has been found for this serious disadvantage; repeated docking 
 and cleaning is the only palliative." 
 
 Fourthly, " The extreme uncertainty as to the quality of the 
 material used, in fact, the small quantity of real good iron of the 
 best ship-building qualities that can be found in the market." 
 
OF IRON SHIPS. 17 
 
 Fifthly, " The prodigious ravages caused by the splinters of iron 
 when the plates are broken and smashed by shot." 
 
 Sixthly, " The far greater facility Tirith which iron ships can be 
 pierced below their armour plating by submarine guns than wooden 
 ships." 
 
 It will be desirable to examine and reply to each of these, so as 
 to find what amount of weight is to be attached to each. 
 
 In regard to the first part of his objections, there is some truth 
 in it when ships are badly built ; but experience has shown in the 
 case of the "Nemesis," the "CleVeland," the "Lady Lansdowne," 
 the " Royal George," the " Garryowen," the " Iron Duke," the 
 " Great Britain," the " Vulcan," and hosts of others, that this 
 casualty may happen with greater ■ impunity and less risk of the 
 loss of the ship than in the case of a wooden vessel, especially 
 when properly put together and fitted with water-tight bulkheads. 
 
 As to the assumed weakness " entailing " all sorts of " compli- 
 cated arrangements " which add to the weight of the ship, it is 
 well known that a wooden ship is a/ar more complicated structure 
 than an iron one, and much weaker; and, in fact, to strengthen such 
 a ship iron is found necessary. It is well known that, comparing a 
 wooden and an iron ship bothofpreciselysimilar external dimensions, 
 the iron one will carry more and be lighter in the proportion 
 of five to six than the wooden one ; therefore this objection is of 
 no moment — whilst in regard to the greater cost of an iron ship 
 the result is a more durable and stronger vessel, and one far 
 cheaper to maintain ; and if the work got out of each during a 
 given period be contrasted with the sums expended in maintaining 
 them during that period, there can be no question that the results 
 will be greatly in favour of the iron ship, assuming, of course, that 
 both are equally well constructed of their respective materials. 
 
 So far as the objection of fouling and corrosion of the hulls of 
 iron ships go, and which have up to a recent period been most 
 serious objections, these are now entirely overcome by Mr. T. B. 
 Daft's patent plan of constructing and sheathing iron ships and 
 vessels, which will be found fully described towards the end of this 
 work. 
 
 As to the objection respecting the " quality of the material 
 used," and " the small quantity of real good iron " that " can be 
 found in the market," this cannot be for one moment entertained. 
 Such a remark well applies to the case of wood, a material the 
 supply of which is constantly decreasing, is slow in growth, and any- 
 thing but desirable ; but this statement respecting iron cannot for 
 one moment bear examination. Bad iron may be bought just as 
 readily as bad wood — perhaps it may be said not so readily, but to 
 say that our great ironmasters cannot produce any quantity of 
 good iron, of any quality that may be required, argues a general ' 
 
 2 
 
18 THE FOULING AND CORROSION 
 
 deficiency in the knowledge of our iron trade and the resources 
 of British industry. 
 
 Low-priced wood cannot be of the quality required for the con- 
 struction of first-class ships, and, whether good or bad, wood will 
 waste more in conversion than iron, with this serious disadvan- 
 tage, that the waste cannot be worked up again as the iron can. 
 
 It is usually understood that the best article requires the best or 
 highest price ; and that where a demand exists, there the supply 
 will be generally found. The same with our iron : if people will 
 but pay the price of the proper quality, any. quantity can be made ; 
 but to suppose that good iron can be supplied at the same price as 
 the inferior quality, which from motives of " economy," has been 
 too much regarded of late years, is a very great mistake. 
 
 The objection of the "ravages caused, by the splinters of iron 
 when the plates are broken and smashed by. shot," would no doubt 
 be of some moment were it the fact that the bare iron shell of some 
 I-'' or f" in thickness were exposed without protection to the full 
 force of the shot"; but as all ships which are likely. to be exposed to 
 this contingency are built with armour plates of a thickness pro- 
 nounced to be sufficient to prevent this effect, it is needless to make 
 further remarks on it. 
 
 In regard to the greater facility of iron bottoms being penetrated 
 by "submarine guns" than wooden ones, there are no such, guns 
 at present in use ; but were there such, iron afibrds siich enormous 
 facilities of adaptation, that little fear need exist on this head. 
 
 One thing is most certain, which is, that no "opinions'" can 
 stand against facts — especially, where facts are fully and truly 
 stated : therefore, whilst facts are in existence, and all relating to 
 them fully understood and brought forward, there can be no doubt 
 that " opinions " not backed by experience will quickly be rightly 
 estimated, and consigned to that position they so rightly deserve. 
 
 "Opinions" have been, and too often are, the great opponents 
 and banes of progress : for instance, they said a steamship could 
 not carry coal enough to cross the Atlantic; that people would 
 never sit behind a locomotive at a speed of twenty miles an hour — 
 in fact, that they would just as soon be tied to the tail of a sky- 
 rocket ; that railways would never get enough people to travel on 
 them to keep them going. In fact, it would be a waste of space to 
 notice more, as the real value of such " opinions " are well known 
 and rightly estimated. 
 
 One very curious objection made by the Controller of the Navy 
 to the use of iron ships for the Navy is this — that none of the 
 ships built by contractors have been completed in the time or at 
 the cost specified, and therefore the building of iron ships is 
 objectionable! — whence he deduces that "this clearly indicates 
 the great uncertainty attending this mode ^f construction." 
 
OP IRON SHIPS. 19 
 
 It would seem, however, that the " great uncertainty " has been 
 in what each ship was to be like ; and this, it seems, could only be 
 found out during construction. Hence the endless alterations, 
 delays, expenses, difficulties, &c., of which the Controller so loudly 
 complains. 
 
 Then, again, he argues that unless such ships are built in 
 Government establishments, "strikes of workmen, strikes of 
 colliers, disputes in trades^ all interfere with the progress of the 
 work, and always to the prejudice of the Government." 
 
 It will be difficult to explain how this will not affect the Govern- 
 ment work in their yards, unless they can show that their iron, 
 coals, &c., are obtained by their own men, or from some country or 
 locality where such things as strikes, &c., are unknown. 
 
 The whole truth of the matter is summed up in the following 
 paragraph in his statement, which runs as follows : " If wood be 
 the material selected, the place of building will be our own dock- 
 yard, with all the plant, appliances, and material at hand ;" and 
 that, therefore, because there is a good stock of wood on hand, and 
 the yards and men are already in existence, it evidently follows 
 that wood must be, and is, the only proper material. 
 
 The strenuous opposition maintained against the use of iron for 
 constructing ships, both by "official'" and "unofficial''' persons, 
 was for a long time successful, and delayed until a recent period 
 the progress of one of the most valuable and important improve- 
 ments of the age. So far as relates to there being the slightest 
 reason in the senseless opposition to the employment of iron for 
 shipbuilding manifested, as it has well been said, by " heads of 
 wood " and " wooden heads," not one practical or reasonable one 
 has been brought forward, and the conclusion irresistibly forced 
 on one is, that «eZ/-interest rather than public interest in this case, 
 as it unfortunately happens in others also, predominated j, and the 
 result has been costly expenditure, uncertain action, the loss of an 
 incalculable amount of valuable time, no settled plan of construc- 
 tion, and general inefficiency throughout. 
 
 Dr. Fairbairn observes — " Thirty years' experience in the appli- 
 ance of iron to the building of our mercantile navy has shown the 
 great superiority of that material for shipbuilding; and much 
 greater progress in this direction would have been made in the 
 Governfnent dockyards but for two reasons, namely, the strong 
 prejudices engendered against iron in the first instance, and the 
 dangers arising from the effects of shot on iron ships in the 
 second." 
 
 There can be no doubt but that this second objection was not a 
 little strengthened by the mode in which the resistance of iron 
 plates to shot was tried, namely, on an old worn-out hull com- 
 posed of thin plating less than a quarter of an inch in thickness ! 
 
20 THE FOULING AND CORROSION 
 
 And if it had been desired to test iron in such a manner as to 
 cause its complete failure for the purpose, a better or more certain 
 mode of action could not have been devised. 
 
 A great bar to the successful adoption of many a good and 
 simple improvement^ and to the saving of vast sums of money^ 
 exists in the fact that it is too much the habit of persons placed in 
 the position of advisers, or invested with the power of adopting or 
 refusing an invention, to consider that it is their duty to invent or 
 improve upon any plan which may be submitted to them, and not 
 to accept it in its integrity, even if it be the plainest and most un- 
 deniable thing that was ever seen. Such an idea as this is a great 
 mistake, and in too many instances has been the cause of a great 
 waste of time and money, and the perpetuation of much that is 
 most undesirable. 
 
 The duties of such persons, and for which they are in many 
 cases paid, is to have suflScient intelligence, knowledge, and prac- 
 tical understanding of the matters placed before them, to be able 
 to see whether any advantage can be derived therefrom, and if so, 
 to advise and assist in \h.evc proper carrying out. One of their 
 greatest benefits should be derived from their not being inventors, 
 but having the capability of sifting the good from the bad, the 
 useful from the useless; and history has shown, and still from 
 time to time places before us, the evils which are introduced and 
 perpetuated by the reverse, but, alas ! with but little benefit to 
 any one. 
 
 A right appreciation of the duties involved by such a position 
 will hardly fail to induce such attention and care being given to 
 their proper discharge as must prove of the greatest benefit and 
 advantage to all concerned. 
 
 Sir Howard Douglas, when consulted by the late Sir Robert 
 Peel as to the use and efficiency of some six iron steamships that 
 were being constructed for the Government, stated that " vessels 
 wholly constructed of iron were utterly unfit for all the purposes 
 of war, whether armed or as transports for the conveyance of 
 troops" ! 
 
 As Mr. Scott Russell has well remarked in his 'Fleet of the 
 Future,' ''Against the use of iron for war-ships, and even for 
 any ships at all, the most inveterate prejudices have long existed 
 in the minds of sailors, shipbuilders, and all who have made naval 
 afi'airs their occupation. It is only the slow growth of intelli- 
 gence, and the gradual formation of practical experience of the 
 great benefits to be obtained by the use of iron, that has been 
 strong enough to overcome some of these prejudices ; and slowly, 
 painfully, one by one, they are now becoming eradicated." 
 
 It has been well observed, that " to be convinced of the impolicy 
 of overlooking improvements merely because they do not accord 
 
OF IRON SHIPS. 21 
 
 with preconceived notions, it is but necessary to look hack for a 
 moment to the numerous instances in which the most important 
 and even palpable improvements have been checked and slighted 
 by ignorance and prejudice." 
 
 The adoption of the screw-propeller in the Royal Navy was long 
 delayed, even after practical proof had been given of its advan- 
 tages, because some wiseacre, who had been a trip at a speed of 
 ten miles an hour in a screw boat, dogmatically asserted that it 
 would not answer, " because a ship propelled by the stern could 
 never steer " ! ! 
 
 When chain cables were introduced for ships, a great opposition 
 was started and maintained against them by a set of persons who 
 seemed to think that "antiquity" was a recommendation; and 
 this outcry was so far successful, that no ship provided with chain 
 cables only, could be insured ! Now, every ship must be provided 
 with them, and rules have been made to decide sizes and lengths 
 for each class of ship ! ! 
 
 It is needless to waste time or space in recording any further 
 instances of the loss and injury which have been caused by igno- 
 rance and prejudice, inasmuch as few men of experience, and still 
 fewer who are given to reading, will be without dozens of cases to 
 prove the truth of this statement. Let us hope that increasing 
 intelligence will remove this tendency, and lead those who meet 
 with a subject they were unacquainted with before to take the 
 trouble to understand it before pronouncing an opinion. 
 
 Unfortunately, to this day hundreds of thousands of public 
 money still continue to be wasted, either by being expended on 
 matters that are well known to be useless, or else by neglect in 
 not spending such sums as would be productive of the saving re- 
 quired when the means exist by which this saving could be made. 
 
 Dr. Fairbairn, in his work on "Iron Shipbuilding," writes as follows 
 of the drawbacks of iron : " The most prominent is that of fouling, 
 and the adhesion of shells and marine growths to the immersed 
 surface of the ship. This is a serious drawback to the application 
 of this useful material ; but we have reason to believe that some 
 antidote for this evil — causing the retardation of speed — will in the 
 hands of our chemical friends receive that attention which the 
 importance of the subject demands, and that "Vae time is fast 
 approaching when immersed iron may become the repulsive instead 
 of the attractive surface of adhesion. The subject of fouling, and 
 the adhesion of barnacles to the hulls of iron vessels, has been 
 since their first introduction a source of trouble and of difficulty 
 for which no effectual remedy has been applied." 
 
 Mr. Grantham, in 1843, remarked that to prevent fouling, 
 " chemical means will doubtless ere long be successfully employed 
 for this purpose." 
 
22 THE FOULING ANl) CORROSION 
 
 Mr. Mallet has observed that he considers it quite possible to 
 render iron as nmch proof against oxidation as gold or platinum. 
 
 Iron, it has been said, from its " superior affinity for oxygen," 
 is liable to rapid decomposition ; and it has ever been a desidera- 
 tum to discover some cheap mode of protecting it, the ordinary 
 methods of painting and tinning not being sufficiently lasting. 
 
 The rapidity with which iron, when exposed to sea- water, both 
 fouls and corrodes, and the almost impossibility of preventing 
 these two serious evils, is well known to have checked the con- 
 struction of iron ships ; and so serious were these objections found, 
 that in the year 1847 the Admiralty was actually intending to sell 
 all those ships which they had of this material ; in fact, they did 
 actually begin to do so. About that time, however, a " composi- 
 tion " was brought forward which seemed to promise a remedy for, 
 or at least a diminution of them ; and this, although only partially 
 successful, seems to have caused a reconsideration of the matter ; 
 and the extended use of iron ships in the merchant navy seems to 
 have led the Admiralty to try the use of iron on a far more exten- 
 sive scale. 
 
 In regard to the general use of iron for men-of-war. Admiral 
 E. P. Halsted observes, " There would still remain at present the 
 very grave objections against iron bottoms, of their liability to foul, 
 and the consequent frequency of resort to the operation of 
 docking." 
 
 Our new iron war-ships are vessels that ought to be able to 
 maintain their speed throughout the term of their commission, and 
 not to require docking every six months to enable them to keep at 
 sea at all. 
 
 The cost of maintaining iron ships will be found extremely 
 trifling, and but for the drawback of fouling, which necessitates 
 constant docking, cleaning, and painting, the chief points would be 
 the rigging and woodwork, which should not, however, require 
 more attention or renewal than those of a wooden ship. 
 
 The cost of construction of the huge iron-clads we are now 
 building may be taken at £50 per ton, builder's measurement, and 
 £60 per nominal horse-power ; to which must be added the cost of 
 guns, rigging, masts, &c., stores, duplicates, and spare gear, which 
 will be found to amount to a considerable sum, and one too large 
 to bear much trifling with. 
 
 The Controller of the Navy, in his ' Statements relating to the 
 Advantages of Iron and Wood, and the Relative Cost of these 
 Materials in the Construction of Ships for Her Majesty's Navy,' 
 printed by order of the House of Commons on the 3rd March, 
 1863, gives the cost of the 
 
OF IRON SHIPS. 23 
 
 TONS. N. H.P. GUNS. 
 
 Warrior of 6109, 1250, and 40, as £254,728. 
 Black Prince,, 6109, 1250, „ 40, „ £249,751. 
 Defence „ 3720, 600, „ 16, „ £173,478. 
 
 Resistance „ 3710, 600, „ 16, „ £178,576. 
 
 Iron, however, witli all its known defects, is steadily displacing 
 wood as a material for the construction of ships ; and there can be 
 no reason to douht that in the course of a few years wood will be 
 a comparatively forgotten material, and only used under most 
 exceptional circumstances, or where prejudice refuses to employ 
 its great rival. 
 
 Without iron, it would have been impossible to construct such a 
 ship as the "Great Eastern" or the "Himalaya," to say nothing of 
 the huge vessels, such as the "Northumberland,^' "Hercules," and 
 other leviathans in course of construction or about to be built, or 
 to have any chance of making them either seaworthy or durable 
 in any other material. 
 
 It is all very well, and sufficiently important in its place, to 
 determine the size, shape, and appointments of our new iron fleet ; 
 but it seems quite out of place to do anything of the sort until the 
 very base and foundation of the structure be settled. If our costly 
 and magnificent broadsides, cupolas, monitors, or whatever they 
 may come to, be dependent upon any description of paints or com- 
 positions, and be really wanted in service, they must all suffer 
 seriously by corrosion and fouling before the end of their com- 
 mission, or come into dock every six months to have their bottoms 
 cleaned and repaired. Besides this is the value of a vessel which 
 begins to foul from the day she leaves her port, and gradually but 
 surely gets worse till her fine and boasted speed is reduced to two 
 thirds, and then half, its original rate. Imagine such a ship in this 
 case, with a clean-bottomed enemy, big or little, tormenting her, 
 and the utility of such a ship to the country and the result of such 
 a contest cannot be for a moment doubted. 
 
 Every objection which could, by the most skilled advocates of 
 every other plan or device, has been raised and answered; and there 
 remains only one straightforward and honest course to pursue, 
 which is to adopt the simplest and best plan, and that which alone 
 cannot possibly do any harm if it did no good, but which, at a 
 moderate computation, it is calculated will save the Royal Navy 
 hundreds of thousands of pounds sterling per annum, whilst its 
 advantages to the merchant service cannot be of less moment. 
 
 Captain C. P. Coles, at the Institution of Naval Architects, in 
 1866, asks, " Is it to be wondered that iron should have been 
 resorted to so generally as a material for shipbuilding, and that the 
 wooden walls of Old England should have been superseded by iron 
 
24 THE FOULING AND CORROSION OF IRON SHIPS. 
 
 walls ? Iron, the marrow of England, is the source of her strength. 
 Iron is invaluable as a material for shipbuilding, being capable 
 of imparting to the structure beauty, high finish, and strength, 
 fulfilling thus all requirements to perfection." 
 
 In spite, however, of the great and rapid progress which has been 
 made in shipbuilding and scientific construction during the past 
 twenty years, and the wonderful improvements in and facilities for 
 the manufacture of iron which have been brought about, it is 
 certain that much more wiU be done, and remains to do; and 
 living, as we do, in an eminently practical age, abounding with the 
 greatest discoveries and inventions, it may well be asked, " who 
 can say that the ' ship of the future ' has yet been discovered, or 
 that the extent to which steam and iron will be developed is even 
 as yet approximately ascertained V 
 
CHAPTER III. 
 
 CHRONOLOGY OP IRON SHIPS. 
 
 The first record the author can find of a boat or floating-vessel 
 made of metal in place of wood is that of one built in 1787, by 
 Mr. John Wilkinson, of Broseley, in Shropshire, who employed 
 iron for this purpose. 
 
 This boat or vessel was 70' long, 6' 8^" wide, drew between 
 8" and 9" water, and carried 33 tons of goods ; was built at Willey, 
 in Shropshire, and used on the Severn. It is most probable that 
 she was a canal barge ; but whatever she may have been, there can 
 be but little doubt that she was the first iron vessel. 
 
 Another small boat, probably of a similar character, was built 
 by Wilkinson soon after, which he employed to carry peat on the 
 canal from the moors where it was cut. 
 
 In the same year, a vessel with the bottom constructed entirely 
 of copper, without any plank whatever, was built ; and another of 
 a similar description in 1789. 
 
 In the year 1794,Brigadier-General Sir Samuel Bentham, K.S.G., 
 constructed a small boat of copper, which he exhibited on the 
 Thames, and also at Queen Square Place, Westminster. 
 
 In 1809, Richard Trevithick, the well-known engineer, and 
 Robert Dickinson, took a patent. No. 3231, for several inventions 
 embodying the use of wrought-iron plates. First, they described 
 a movable caisson, or floating dock, made of this material. The 
 internal figure resembled that of a boat. It had a flange six feet 
 wide, extending horizontally outwards from the upper edge, for the 
 workmen to stand upon, and also to strengthen the caisson ; and 
 it was surrounded by an air-chamber, or by air-chambers, consist- 
 ing of wrought-iron plates, riveted together so as to form a semi- 
 cylindrical hollow protuberance, extending along the sides of the 
 caisson horizontally. Water was to be admitted into it until it was 
 wholly immersed ; and then, when hauled under the bottom of the 
 ship, the water was to be pumped out. 
 
 Second, they described iron ships — " ships of war, East-India- 
 men, and other large decked vessels.'' The decks as well as the 
 sides of such ships were to be of plates of wrought iron, " riveted, 
 or joined by screws." 
 
26 THE FOULING AND CORROSION 
 
 Thirds they proposed to make "masts, bowsprits, yards, and booms 
 of wrought iron, out of plates riveted or screwed together in hollow 
 or tubular forms. These masts being hollow tubes, the upper 
 masts may be made to slide into the lower mast." 
 
 In 1810, Sir Samuel Bentham proposed to the British Govern- 
 ment the introduction of iron for shipbuilding, on account of the 
 increasing scarcity of timber ; but the Admiralty refused to listen 
 to his proposal. A guardship was just then about to be built for 
 Chatham, and he endeavoured to get it built of ironj and as it 
 would thus be constantly under the observation of the dockyard 
 officials, the influence of that metal on the compass, as well as 
 other objections, could be ascertained ; but the Admiralty would 
 not give their consent, and from this period the introduction of 
 iron for shipbuilding was abandoned to private enterprise, and has 
 received but little development from Government. 
 
 In 1815, Mr. Thomas Jevons, of Liverpool, built a small iron 
 pleasure-boat, which he launched on the Mersey ; and this seems 
 to have been the first iron boat used in salt water. This boat was 
 built by Mr. Joshua Horton, of Tipton, near Birmingham, and 
 fitted up in Liverpool by Messrs. Hunter and Humble. 
 
 In 1818, Sir John Robison had an iron vessel (which he had de- 
 signed in 1816) built for the passenger-traflBc on the Forth and 
 Clyde Canal, by Mr. Thomas Wilson, at I'askine, on the Monkland 
 Canal, some six miles from Glasgow. Shewas called the "Vul- 
 can," and was 61'xll'x4' 6"; was flush or carvel built; had 
 bulkheads with diagonal stringers ; the frames were made from flat 
 bar-iron, worked into the required shape in a cast-iron grooved 
 block, and were placed 2' apart. The plates were 2' broad, 
 and put on vertically; they butted on each frame, and there were 
 consequently two rows of . rivets in each frame. The keel was 
 formed of two plates, |" x 12", placed side by side in a vertical 
 position, reaching to the top of the floors. There was a "doubling 
 strake" round the gunwale, made of \" plate, 13" wide. This 
 -plate was turned into angle-iron 9"x 4", which gave great strength 
 to the hull longitudinally, and supported the wooden stringer 
 which ran fore and aft on each side. She had an iron lower mast, 
 which was used as a chimney for the cabin-stove in winter, a;nd 
 did duty as a ventilator for the cabin in the sumnier, and the sides 
 of the cabins were of glass. 
 
 It is stated that this boat was in existence in 1865. 
 
 In 1820, the " Aaron Manby," iron steamboat, was commenced 
 at the Horseley Iron Works, and completed in 1821. She was 
 sent up to London in parts, and put together in the Surrey Canal 
 Dock, where she took in a cargo of linseed and iron castings, and, 
 under the command of the late Admiral Sir Charles (then Captain) 
 Napier, M.P., with Mr. Charles Manby (so long Secretary of the 
 
OF IRON SHIPS. 27 
 
 Institute of Civil Engineers) as chief engineer, went from London 
 direct to the Port Royal at Paris without unloading any portion 
 of her cargo. 
 
 In 1825, the late Mr. John Grantham, of Liverpool, had a small 
 iron steamer, of 10 nominal horse-power, built by the Horseley Iron 
 Company, which he placed on the Shannon. The vessel was com- 
 menced in 1824, was put together in Liverpool, and sent across to 
 Lough Derg. 
 
 In 1827, Mr. David Napier built the " Anglia" steamer, which 
 had an iron bottom, and woodeu sides above water, to ply on 
 Loch Eich. She was afterwards called the "James Gallacher," 
 and plied on the Clyde. Her dimensions were as follows : — 
 Length, 62' 8"; breadth, 13' 0" ; depth, 4' 6"j gross tonnage, 
 49|-f tons. 
 
 In the year 1829, the laite Mr. "William Gravatt, C.E., designed, 
 and had constructed by the late firm of Fenton and Murray, of Leedsj 
 an iron paddle steamboat, with a horizontal tubular locomotive 
 boiler, the paddle-shaft being placed in front of the smoke-box, 
 against which the plummer-blocks were bolted. The lines of this 
 boat were taken from a fine gig built by Roberts, boat-builder, of 
 Lambeth. This is believed to have been the first steamboat in 
 which a tubular boiler was used. 
 
 In 1829-30, Mr. Neilson, of Glasgow, altered an old iron passage- 
 boat of the Forth and Clyde Canal Company, the " Cyclops," built 
 in 1825, into a stern-wheel boat on the American plan, with a 
 single engine of 14 nominal horse-power, and a single paddle- 
 wheel ; and though but ill adapted to give the required results, the 
 boat proved so satisfactory that a second was built for them by 
 Mr. Neilson. 
 
 In October, 1829, the first iron vessel built on the Mersey was 
 launched by the well-known firm of Messrs. William Laird and Sons 
 (the late Mr. William Laird and the present Mr. John Laird, M.P.) . 
 This vessel was 60 ft. long by 13 ft. beam, and 60 tons measure- 
 ment. In the year 1831, two others of a similar size were built by 
 the same firm. 
 
 In the same year, the firm (then known as McGregor Laird 
 and Co., consisting of Mr. William Laird, the late Mr. Fawcett, and 
 the late Mr. McGregor Laird, the African traveller) built and 
 launched the steamer " Elburka," of 70 ft. in lengthy 13 ft. beam, 
 and 15 horse-power, which went out with the late Mr, McGregor 
 Laird, in 1832, as one of the Niger Expedition. This was the first 
 iron vessel that ever made an ocean voyage. 
 
 In the year 1833 they built the " Lady Lansdowne'^ steamer, 
 which was 130 ft. long, 17 ft. wide= 148 tons, and had engines of 
 80 horse-power; and the "John Randolph," of HO ft. long, 22 ft. 
 wide =249 tons, and had engines of 60 horse-power. 
 
28 THE FOULING AND CORROSION 
 
 In the year 1834 they built the " Garryowen," of 130 ft. long, 
 21 ft. 6 in. wide =263 tons, with engines of 80 horse-power ; the 
 "Euphrates," of 105 ft. long, 19 ft. wide=179 tons, with engines 
 of 50 horse-power; and the "Tigris," of 90ft. long, 16ft. wide 
 = 109 tons, with engines of 20 horse-power. 
 
 The " Lady Lansdowne" was built for Ireland, and was sent out 
 to Lough Derg in pieces — put together, finished, and launched 
 there. 
 
 The " John Eandolph" was for the United States, and was sent 
 out in pieces to Savannah — put together, completed, and launched 
 there ; and this is stated to be the first iron steamer ever used in 
 America, and she was still in existence up to the period of the late 
 war, in good working order. 
 
 The " Grarryowen" was completed and launched at the works at 
 Birkenhead, and steamed round to the Lower Shannon, where she 
 continued at work until 1866, when she was sold to go to the coast 
 of Africa, after being carefully examined, and found in very good 
 order, although she had gone through thirty-two years' hard work. 
 
 The " Euphrates" and " Tigris" were shipped in pieces by vessel 
 to Beyrout, and with engines and boilers transported with great 
 difficulty across the desert by General Chesney and the men of the 
 Euphrates Expedition, and put together and completed on the Eu- 
 phrates by men sent out by the firm. With the facilities of the 
 present day, this would be a comparatively easy undertaking, but 
 at the period it was carried out was certainly an arduous and novel 
 feat. 
 
 The "Tigris" was lost in a hurricane on the river; and the 
 " Euphrates," after working for many years as a steamer, had her 
 engines and boiler taken out, which were put into another vessel, 
 and her hull was used as a lighter on the river Indus. 
 
 All these early vessels were regularly built and framed like a 
 wooden vessel, were very strong, and would have been fit to sail 
 to any part of the world; and the "Lady Lansdowne" and "Garry- 
 owen" were capable of putting to sea under any circumstances. 
 
 In 1836, they built the " Eliza Price," to ply between Liverpool 
 and Birkenhead, which was 85' 8"x 17' 9"x 7' 9"= 88 tons, with 
 engines of 54 horse-power. 
 
 In 1839-40, they constructed for the Admiralty the " Dover," 
 used to carry the mails between Dover and Calais. She was 
 110' 5" X 21' 0" X 10' 6", and when last heard of, a year or two ago, 
 was on the coast of Africa, and in good order. 
 
 In the year 1830, Dr. William Fairbairn, in conjunction with 
 his partner Mr. Lillie, built at Manchester the iron paddle-boat 
 " Lord Dundas," for use on the Forth and Clyde Canal. The hull 
 was 68' X 11' 6" x 4' 6", built of light angle and T iron, with plates 
 To" thick, and had engines of 10 nominal horse-power, working a 
 
OF lEON SHIPS. 29 
 
 paddle-wheel placed in the centre of the boat, in a wheel trough 
 extending the whole length of the hull. The light draught of this 
 boat was 16", and she could accommodate 100 to 150 passengers. 
 Dr. Fairbairn informs the author that he made the voyage from 
 Liverpool to Glasgow in her ; and she proved so successful that 
 his firm built eight more of a larger size within the next two or 
 three years for Scotch canals ; two paSsenger-boats with 40 nominal 
 horse-power engines for the Humber j and two for the lakes of 
 Zurich and Wallenstadt in Switzerland, which, after being tried, 
 were taken to pieces and sent out. 
 
 In 1831, Dr. Fairbairn built the "Manchester," of 70' 0" 
 X 15' 0" X 8' 0", with engines of 30 horse-power ; in 1833, " La 
 Reine des Beiges," of 75' 0" x 14' 0" x 6' 0", with engines of 24 
 horse-power, which went from Liverpool to Ostend. In 1833, 
 he built the " Minerva," of 98' 0" x 15' 6" x 7' 0", with 40 
 horse-power; which boat was sent in pieces to Hull, put together, 
 and made the voyage to Rotterdam in thirty-three hours, and then 
 steamed up to the Rhine Falls, where she was again taken to pieces 
 and carried overland to Lake Zurich. 
 
 The difficulties which were found to exist in an inland town like 
 Manchester for the construction of iron vessels led to the removal 
 of this branch of the business to London in the years 1834-5, where, 
 at the works, Millwall, Poplar, Dr. Fairbairn constructed upwards 
 of eighty vessels of various sizes, including the " Pottinger," of 1250 
 tons and 450 nominal horse -power, for the Peninsular and Oriental 
 Company; the " Megsera" and other vessels for the British Govern- 
 ment, and many others ; thus introducing iron shipbuilding on the 
 river Thames; and in 1848 he retired from this branch of his 
 business. 
 
 In 1835-6, the well-known firm of Messrs. Ditchburn and Mare 
 commenced iron shipbuilding on the Thames, which they carried 
 on for many years in Bow Creek, the site of the present Thames 
 Iron Works, and at a later period were followed by Messrs. David 
 Napier, Samuda Bros., M. and H. L. Wigram, Miller and 
 Ravenhill, Robinsons and Russell (afterwards the well-known firm 
 of J. Scott Russell and Co., who built the " Great Eastern," and 
 whose premises included those formerly occupied by Messrs. Fair- 
 bairn and Napier), Joyce, Dudgeons, Rennie, and others. 
 
 In 1831, an iron steamer called the "Fairy Queen ^' was built 
 at Glasgow by John Neilson, of Black Quarry and Oak Bank, which 
 was taken from the building-yard to the Clyde on a truck, and 
 launched broadside on into the river, in a more successful manner 
 than was the case with the " Great Eastern " at a later period on the 
 Thames. Her dimensions were as follows : — Length, 95' 2"; breadth, 
 11' 5"; depth, 8' 3"; 39|i tons register. In 1834 she was length- 
 ened. 
 
30 THE FOULING AND COKROSION 
 
 In 1832-3, Messrs. Thomas Wingate and Co:, of Whiteinch, near 
 Glasgow> built at Springfield an iron lighter, which was taken to Port 
 Eglinton, and launched in the Paisley Canal. This firm, in the 
 year 1837, put' a pair of side lever engines, with 60" x 6' stroke 
 cylinders, into the wooden steamer " Sirius," of 700 tons ; the first 
 steamer that ever crossed the Atlantic. 
 
 In 1834, Mr. David Napier' built the iron steamer " Kilmxm," 
 of 119' 7" X 15' 5" X 8' 5" = 144 tons, with engines of 70 horse- 
 power, which plied between Glasgow and Kilmun. 
 
 In the same year, the " Swan/'' of 10 horse-power, with engines 
 by James Gray, of Glasgow, was built by John Neilson, to ply 
 between Londonderry and Strathbane. 
 
 In 1835, Mr. David Napier built the " Loch Lomond," to ply 
 on the loch of that name. She was 92' 9" x 15' 1" x 7' 0" = 76 
 tons, with engines of 40 horse-power. 
 
 In the same year, Messrs. Tod and McGregor built the " Vale of 
 Leven," to ply between Glasgow, Dumbarton, and Greenock: She 
 was 93' 1" X 16' 5" x 7' 6" =■ 121 tons, with engines of 51 horse- 
 power. The "La Plata," with two horizontal engines of 10 horse- 
 power, was this year built at Johnstone, and engined by Tod and 
 McGregor. 
 
 In 1836, Mr. John Neilson built the "Maid of'Claro/' for 
 Yarmouth. She was 56' 1" x 9'- 8" x 7' 1" = 35 tons. 
 
 la the same year, Messrs. T. Wingate and Co. built the 
 "British Queen," to ply between Glasgow and Garelochhead. She 
 was 125'-4" X 16 5" x 8' 5" = 144-;^ tons, with steeple engines 
 of 90 horse- power. 
 
 Messrs. Tod and McGregor also built in this year the " Royal 
 Tar," to ply between the same places, and the " Express " also, 
 which plied to Kilmun besides. The "Royal Tar" was 125' 7" 
 X 16' 6" X 8' 8" = 141 tons, with engines of 80 horse-power ; and 
 the " Express " was 130' 4" x 16' 4" x 8' 5" = 150 tons, with 
 engines of 94 horse-power. They also at the same time built 
 the " Shamrock," of 116' 1" x 16' 3" x 9' 2" =160 tonsj with 
 engines of 77 horse-power, to ply between Waterford and New 
 Ross ; and Mr. John Neilson built the " Egremont," of 87' 7" 
 X 17' 4" X 8' 2" = 129 tons, with engines of 70 horse-powfer.' 
 
 In 1837i Messrs. Tod and McGregor' built the " Benledi," to 
 ply.between Leith and Dundee. She was 124' 5" x 15' 9" x 8' 6" 
 = 102 tons register, with engines of 77 horse-power; and the 
 "Rothsay Castlei" to ply between Glasgow and Rothsay. This 
 vessel was 133' 8". x 17' 0'^ x 8' 6" = 180 ton3, with engines of 
 90 horse-power. 
 
 In the same year, Messrs. T. Wingate & Co. built the " Loch 
 Lomondj" for Dumbarton. She was 101' 8" x 16' 5" x 8' 5" 
 = 7'7 tVt tons register, and had steeple engines of 52 horse-power. 
 
OP IRON SHIPS. 31 
 
 In 1840 this vessel was sold to some parties in Hamburgh, and 
 used to ply on the B.hine. In the same year they built the 
 "Prince Albert," for Liverpool, which was 107' 6" x 16' 5'' 
 X 8' 1" = 1 22 tons, with engines of 60 horscrpower^ 
 
 Messrs. Smith and Rodger the same year constructed a double 
 cigar-ship called the "Victoria," whicli consisted of two cigars, 
 92' 8" X 7' 0", set side by side, and a hurricane deck, with a paddle- 
 wheel in the centre propelled by engines of -75 horse-power. 
 
 In 1838, they built, the "Plenipo," to ply between Glasgow and 
 Kilmun. She was 118' 5" x 15' 7" x T 2" = 113 tons, and 
 had steeple engines of 65 horse-power. 
 
 Messrs. Tod and McGregor in this year built the "Royal 
 Sovereign," to ply between Glasgow and Liverpool. She was 
 177' 5" X 21' 2" X 12' 1" = 446 tons, and had engines of 220 
 horse-power. 
 
 After this date, iron paddle-steamers were built in rapid succes- 
 sion; but screws did not come into general use as cargo-boats till 
 after 1845. 
 
 So far as the author can find, transverse water-tight iron bulk- 
 heads in iron steamships were introduced by the late Mr. Charles 
 Wye Williams, who first employed them in the "Garryowen," iron 
 steamer, in (it is said) the year 1833-4. Transverse bulkheads 
 made water-tight in wooden ships were introduced in this country 
 by Captain Shanks, about the year 1790, in a vessel called the 
 "Trial," and used by Sir Samuel Bentham> K.S.G., in his seven 
 experimental vessels designed in 1794. Longitudinal bulkheads 
 were introduced by Sir Samuel. 
 
 In 1838, a Mr. Wheelwright, of Regent Street, London, brought 
 forward the " longitudinal '' system of construction, which has 
 since been brought to such perfection by Mr. Seott Russell in the 
 " Great Eastern," and numerous other vessels designed and con- 
 structed by him before and since, and has given very satisfactory 
 results in praotice. This is manifestly the proper way of, m-aking 
 a ship of great strength, instead of using the ordinary vertical angle, 
 iron frames which give no strength in a longitudinal direction. 
 Mr. Wheelwright published a small pamphlet on this plan in 1838, 
 which was accompanied by plans and sections, and it may be seen 
 in the library of the Institution of Civil Engineers. 
 
 The first iron sailing-vessel built in Liverpool was the ship- 
 rigged vessel " Ironsides," of 248 tons register, which was built by 
 Messrs. Jackson and Gordon,, for Messrs. Watson Bros., and 
 launched in October, 1838- 
 
 In, 1840, Messrs T. Wingate and Co. built the first iron sailing- 
 vessel constructed in Scotland. She was called the " Henrietta," 
 ' and was 57' 8" long x 16' h". beam, x 7' 4" deep, = 61-'?<jV tons. 
 
 In 1840-2, Messrs. R. Saunderson and Co. built the " Vulcan," 
 
32 THE FOULING AND CORROSION 
 
 of 63' 0" X 14' 4" X 9' 0", and the "Cygnet/-" of 60' 4" x 18' 0" 
 X 10' 1", which were employed in the trade from Leith to Rotter- 
 dam ; and in 1841, Messrs. Anderson and Gilmore, of Govan, 
 built the "Waterloo," of 78' 8" x 30' 0" x 9' 0", which traded 
 from the Clyde to the West Indies. 
 
 In the year 1839-40, the first iron steamer for the Royal Navy, 
 the " Dover," was built by Messrs. Laird, of Birkenhead ; and 
 about 1843, the British Government began to extend their employ- 
 ment of this material. 
 
 In 1841, the "Great Britain," iron-screw steamer, of 3500 tons 
 and 1000 nominal horse-power, was commenced at Bristol. Her 
 dimensions are as follows: — Length over all, 320'; beam, 51'j depth, 
 31' 4"; and the lines were designed by Mr. Paterson, of Bristol. 
 This vessel was launched in 1843, after a great expense and trouble 
 in enlarging dock-gates, &c., to get her through (reminding one of 
 the story of Robinson Crusoe and his " big boat "), had been got 
 over ; she made several voyages to America, and having been run 
 ashore on the coast of Ireland, where she passed through the storms 
 of a very severe winter, was finally got off, taken to Liverpool, and 
 having undergone alterations in engines, boilers, and fittings, was 
 placed on the Australian trade, where she still remains, and is known 
 as one of the most regular and successful ships in that employment. 
 
 In 1854, the construction of the " Great Eastern," paddle and 
 screw combined, was commenced at Millwall, London, by Messrs. 
 J. Scott Russell and Co. The length of this vessel on deck is 
 692' 0", her beam 82' 6", and depth 58'; tonnage, B. M., 
 = 24,360 tons; paddle engines, 1000 nominal horse-power; screw 
 engines, 1600 nominal horse-power. The lines of this vessel were 
 designed by Mr. Scott Russell, and the ideas on which a ship to 
 fulfil the conditions proposed to be accomplished by the company, 
 which was got up to construct her, were promulgated before 1838 
 by a Mr. Holmes, and in 1840 by Lieut. Radford, R.N., the latter 
 of whom published a small work on the subject, in which nearly all 
 the advantages and reasons for the construction of such vessels as 
 the "Great Eastern," which were brought forward at a later 
 period, were fully entered into. 
 
 It is recorded that when Mr. Holmes first broached this subject 
 at the Admiralty and elsewhere, they laughed at the idea, and 
 begged him to desist from pursuing so fatile a plan. 
 
 The " Great Eastern " was built " broadside on," with her bow 
 down the river, and the first attempt at launching her was made 
 by Mr. I. K. Brunei, the company's engineer, on a new plan 
 invented by him, on the 3rd November, 1857, but resulted in a 
 total failure. The reason of this was, that instead of employing 
 greased wooden ways, the experiment was persisted in of launching 
 on iron rails, the cradles having bars of iron placed transversely to 
 
OF IRON SHIPS. 33 
 
 the longitudinal Great Western rails under them. The great 
 friction and bite of the iron on iron^ and a deficiency of bearing 
 surface on the ways when the ship had moved from the thickly 
 piled surface on which she had been built, brought everything to a 
 dead lock ; and it was only by the employment of some twenty- 
 two of the most powerful hydraulic rams or presses which could 
 be obtained, including those used to lift the Britannia tubular 
 bridge, that the ship was pushed by main force into the river and 
 floated off on the 31st January, 1858, after many weeks' almost 
 constant exertions, both night and day, and the expenditure of an 
 unknown number of thousands of pounds. 
 
 It is worthy of note that, although this huge vessel remained on 
 the ways with some 140 feet at each end hanging in the air, and 
 totally unsupported for a period of three months all but three 
 days, it was found, when her sheer was tried after she was afloat, 
 that the change in her length of 693' 0" could be expressed by the 
 fraction of an inch ! It is to be regretted that the want of proper 
 management should have hitherto prevented the capabilities of this 
 vessel from having been properly and thoroughly developed, but so 
 far it would seem that, for weights moved, and power or force 
 expended in doing it, at the same speed as other vessels of a large 
 class, she will bear a very favorable comparison; and the success 
 attending the laying of the Atlantic Telegraph cable by her means 
 is suiScient almost to have justified her construction specially for 
 this purpose. 
 
 In 1854-5-6, during the war with Russia, the British Government 
 built several wooden floating batteries of 1469 to 2000 tons, cased 
 or plated with rolled iron four inches thick, and provided with 
 high-pressure engines of 150 to 300 nominal horse-power, driving 
 the screw propeller. These vessels were introduced by the 
 Emperor of the French. 
 
 In 1859 the first iron ship, plated with rolled iron 4<^" thick, the 
 '' Warrior,'^ of 6038 tons, and 1350 nominal horse-power, was laid 
 down by the British Government, and launched in 1861. Her 
 length is 380'; beam, 58'; depth, 43'.- 
 
 Since this period the iron-built iron-plated vessels have been 
 increased in size, some being 6631 tons and 1350 nominal horse- 
 power, with a length of 400 ft. and a breadth of 59 ft., with armour 
 5^" in thickness, such as the " Minotaur," the " Agincourt," and 
 " Northumberland." 
 
 Besides these are numerous smaller vessels of 3700 tons, down 
 to vessels of 700, both sizes carrying 4^" armour plates; and the 
 "Hercules," '' Monarch," "Captain," and "Penelope," will have 
 armour plates of 8" and 6" in thickness. * 
 
 It is said that designs are now prepared for iron vessels of 
 10,000 tons, with 63 guns on two decks, and iron armour of 5^" 
 
 3 
 
3-i THE FOULING AND CORROSION 
 
 thick, in which no teak or wood backing is to be used, and their 
 length is to be over 400 ft. 
 
 In the year 1838 the Committee of Lloyd's Register classed the 
 first iron vessel that had ever been guaranteed as " fit for the safe 
 conveyance of dry and perishable cargoes." " This barque was 
 appropriately named the ' Ironsides •' she was 271 tons register, 
 was built at Liverpool by Messrs. Jackson and Gordon, for Messrs. 
 Cairns and Co. She was launched on 17th October, 1838, and 
 was built of angle iron aud plate iron, much in the same manner 
 as iron ships are now built. She performed her first voyage to 
 Rio de Janeiro and back without damaging any cargo. She was 
 classed by the Committee of Lloyd's Register, after careful con- 
 sideration, on the 15th November, 1838, as ' built of iron,' with 
 no letter. From this date until 1844 the Committee of the 
 Register Book continued to class iron ships by the designation 
 'built of iron,' but with no letter." 
 
 From 1844 to 1854 the Committee improved the classification 
 by marking them A 1, " built of iron," but this character was 
 limited to six years. However, before the termination of this six 
 years' classification the number of iron ships had so increased, 
 and the demands for some kind of higher class based on admitted 
 rules was so general, that the Committee of Lloyd's Register con- 
 sidered it necessary to form a code of rules for their own guidance 
 and for that of the builders of iron ships; but having in vain 
 solicited the assistance and concurrence of the iron shipbuilders 
 throughout the country to form such rules, they in 1854 appointed 
 a select committee, composed of members of their board more 
 conversant with shipbuilding, who, with the assistance of their 
 own surveyors (by collecting the scantlings of iron ships already 
 classed), compiled their celebrated ' Rules and Tables of Scantlings ' 
 for ships of six, nine, and twelve years' grade, and which, when 
 confirmed by the general committee, was prefaced as follows : — 
 " Considering that iron shipbuilding is yet in its infancy, and that 
 there are no well-understood general rules for building iron ships, 
 the committee have not deemed it desirable to frame a scheme 
 compelling the adoption of a particular form or mode of construc- 
 tion, but that certain general requirements should be put forward 
 having for their basis thickness of plates and substance of frame, 
 showing a minimum in each particular to entitle ships to the 
 character A for a period of years, subject, however, to . certain 
 periodical surveys, and also to a continuation of such character 
 should their state and condition justify it on subsequent examina- 
 tion." 
 
 Although the mode of constructing iron ships primarily intended 
 by these rules is the original and ordinary one of vertical frames 
 and longitudinal plating, the committee do not hesitate to admit 
 
OF IRON SHIPS. 35 
 
 into the Register Book, and into the same classes, vessels other- 
 wise constructed, if of equal strength, and have classed ships with 
 longitudinal frames or with diagonal frames, and many with double 
 or cellular bottoms for water ballast, &c. 
 
 Thus, by wise and practical rules, administered with even- 
 handed justice and impartiality, has this important society striven 
 to assist the shipbuilders and shipowners of this country to im- 
 prove the merchant shipping of Great Britain and her colonies, 
 and are reaping a well-merited reward in the general improvement 
 of the structure of ships, and in the increasing confidence reposed 
 in them by all parties, interested in shipping, having never had at 
 any time so many vessels building in conformity to their rules, 
 under the special supervision of their surveyors, as at the present 
 moment. 
 
 The endeavours of this committee have been directed to carry 
 into effect as far as possible a uniform system of construction, 
 which shall, in all essential points, secure strength of hull, wise 
 disposition of material for economy, provisions for the safety of 
 life and property, and durability ; to encourage and not to retard 
 the introduction into naval architecture and shipbuilding of every 
 real improvement in the mechanical structure of ships that may 
 better adapt them to the special object they may have in view. 
 The rules allow the classification of a ship of good material, of 
 sound workmanship, and of skilful design, to take rank according 
 to her intrinsic qualities, in whatever manner those good qualities 
 may have been achieved. 
 
 The author begs to return his best thanks to Dr. Fairbairn for 
 the valuable information he has afforded him regarding the origin 
 of iron shipbuilding on the Thames; to Messrs. Laird Brothers, 
 John Laird, Esq., M.P., and Mr. C. B. Bean, of the 'Liverpool 
 Albion,' for the same respecting the town of Liverpool; and to 
 Messrs. T. Wingate and Co., engineers and iron shipbuilders, of 
 Whiteinch, near Glasgow, for that relating to the Clyde. 
 
 To his applications for information respecting iron ships on the 
 Tyne and the east coast, the author has not received any replies, 
 and has been unable to collect any particulars on this part of the 
 subject. 
 
 In conclusion, he would say that he will be glad to receive 
 authentic information, facts, and dates, relating to the early history 
 of iron ships and boats, for use in future editions, and will esteem 
 it as a favour if any of his readers who can, will kindly take the 
 trouble to supply him with such information as they may possess 
 or obtain on the subject. 
 
CHAPTER IV. 
 
 SHEATHING. 
 
 The protection of the submerged portions of a ship's huU^ and 
 the necessity of it, whatever material the ship may be constructed 
 of, seems to have been long acknowledged and practised. The 
 materials employed for this purpose are almost innumerable, and 
 we find wood, copper, lead, zinc, porcelain, Roman cement, Port- 
 land cement, leather, tin, yellow metal, india-rubber, tinned iron, 
 woven metal and vegetable fabrics, brass, glass, plaster, &c. &c. ; 
 in fact, it would seem that almost everything had at one time or 
 other been pressed into the service. 
 
 Atheneus, quoted by Ewbank, informs us that the ship of 
 Archimedes was fastened everywhere by copper bolts weighing 
 ten pounds each and upwards, whilst the bottom was sheathed 
 with lead. 
 
 Lead was used as a material for sheathing in the second century, 
 for Alberti tells us, in his work on architecture, which was pub- 
 lished in the fifteenth century, that whilst he was writing that 
 book a ship, called " Trajan's Ship," was raised from the bottom 
 of Lake Riccia, which had been submerged for above 1300 years, 
 and that " over all there was lead sheathing fastened on with little 
 copper nails." 
 
 A boat, thirty feet in length, was found in the fifteenth century 
 sunk in the Mediterranean in twelve-fathoms water, which had 
 the deck covered with paper and linen, and sheets of lead fastened 
 with gilt nails over all ; and when stripped off, parts of the covered 
 portion were found quite dry, the boat being estimated to have 
 been 1400 years submerged. The hull was of cedar and larch. 
 
 A Roman ship sunk in the Lake of Nemi was found to have 
 been coated with bitumen, over which sheets of lead had been 
 nailed with gilt nails. The seams of this vessel were caulked with 
 tow and pitched, the material of the hull being larch. 
 
 In the reign of Henry VIII large vessels had a coating of loose 
 animal hair attached with pitch, over which a sheathing board of 
 about an inch in thickness was fastened, " to keep the hair in its 
 
THE FOULING AND COREOSION OF IRON SHIPS. 37 
 
 glace." It seems, however, that sheathing the hull or building 
 another over it was not approved of by these early navigators, and 
 in 1668 the officers of the fleet fitting out under Sir Thomas 
 Allen to attack the Algerians petitioned that they might not have 
 their vessels " so encunxbered," as they " were always unable to 
 overtake the light-sailing unsheathed vessels of the enemy." This 
 petition was granted on condition that the ships' bottoms were 
 cleaned very frequently. 
 
 In the reign of Charles II the " Phoenix " was sheathed with 
 lead, and soon after about twenty ships were so sheathed, milled 
 lead fastened with copper nails being used. 
 
 In 1667, during the same reign, it is noted "that wee and 
 divers of our subjects are att great charges in the sheathing shipps 
 for the streights and other foreign parts." For many years, and 
 up to the middle or latter end of the last century, the sheathing 
 generally in, use seems to have been a doubling of the skin of the 
 ship with wood, which was kept constantly payed over with tar, 
 grease, or a mixture of these compounds. The writer of these 
 pages remembers a small schooner which was so constructed, and 
 after some time had a sheathing of copper or yellow metal laid on 
 this wooden sheathing. 
 
 In 1670 a patent was granted for the use of milled lead for 
 sheathing, and it was ordered that "no other than milled lead 
 sheathing should be used on His Majesty's ships." In the year 
 1700 lead was acknowledged to have proved a failure, and the use 
 of wood sheathing was again resorted to. 
 
 In 1677 and 1678 Sir John Narborough and Sir John Kemp- 
 thorne complained that the rudder irons of the " Plymouth " and 
 '^Dreadnought" were so much eaten as to make it unsafe for 
 them to go to sea; and in 1682 similar complaints were made of 
 the eflfects of lead in contact with iron. 
 
 In the year 1683 a commission was appointed to investigate 
 the subject, and the result was that lead sheathing was abandoned. 
 In the latter half of the last century, however, the " Marlborough " 
 was sheathed with lead, and laid up in ordinary at Sheerness. In 
 a few years after, or in 1770, she was docked at Chatham, and it 
 was found that the lead had eaten away the iron fastenings very 
 considerably, in consequence of which the lead was stripped off, 
 and wood sheathing substituted. 
 
 Alloys of lead have also been tried, but all produced similar 
 results, and were consequently abandoned. 
 
 Lead stands next to copper in its galvanic action on iron, and 
 although it is far cheaper than copper, still its injurious effects, 
 and the trouble, complication, and expense, necessary to insulate 
 it, preclude its use as a material for sheathing iron ships. 
 
 In 1687 a patent was obtained for using rollers to, mill lead into 
 
38 THE FOULING AND CORROSION 
 
 sheets, " as well for the sheathing of ships as for any other use or 
 purpose whatsoever," and in 1728 another patent was obtained for 
 a " new method of sheathing and preserving the planks of ships." 
 This consisted of "rooled copper, brass, tin, iron, or tinned 
 plates." In 1779 was patented a "compound metal capable of 
 being forged when red hot or when cold, more fit for making bolts, 
 nails, and sheathing for ships, than any metals heretofore used." 
 This was a very close approach to Muntz's metal. In 1800 was 
 patented " red, yellow, and white sheathing," consisting of various 
 mixtures of copper, zinc, and tin. This was again a near approach 
 to Muntz's metal. In 1805 the manufacture of zinc into sheathing 
 for ships was patented. 
 
 From this period numerous patents were obtained for materials 
 or their mode of application in sheathing vessels, such as electro- 
 typing the whole hull, and various other contrivances, most of 
 them exhibiting an utter disregard of chemical knowledge, such, 
 for instance, as that of Mr. J. E. M'Connell, who in 1852 proposed 
 to apply sheets of brass or copper directly to the hull of the vessel 
 and riveted thereto, without the interposition of any insulating 
 material, galvanic action being thus set at defiance ! Others, 
 again, proposed to sheathe the iron hull with wood, to which the 
 metal sheathing may be applied, as in a wooden ship ; and then, 
 again, various nostrums against fouling and corrosion are patented, 
 such as glass, phosphorus, arsenic, &c., all of which are either so 
 absurd or worthless as not to need further attention. 
 
 Sheathing or protecting the hulls of iron ships comprehends the 
 following points :— Materials used, mode in which they are applied, 
 principles involved in their action, their advantages or disad- 
 vantages, cost, durability. 
 
 The materials used have been metallic or non-metallic. The 
 disadvantages of the metallic are that, unless carefully selected with 
 reference to their action on the iron hull of the ship, they give rise 
 to one or all of the following serious objections : — They do not fail 
 to set up a serious destructive galvanic action with the hull of the 
 ship, and thus become rapidly foul, at the same time dooming the 
 hull to certain destruction, and their application has been a com- 
 plicated and unsatisfactory process. They are not readily applicable 
 to an iron ship, unless she be specially constructed for the purpose 
 of being sheathed, with facilities for attaching the plates. 
 
 The non-metallic sheathing is either in the form of a paint and 
 smeared on, or else laid on, plastered or spread as a paste or 
 mortar, or stuck on by means of some adhesive glue or other 
 medium. As the adhesion is merely that of plaster on a wall, and 
 is influenced by wet, damp, or the state of the atmosphere when being 
 laid on, and it cannot be attached with such a degree of firmness 
 as can be done with sheets of metal, none of them iare calculated 
 
OF IROK SHIPS. 39 
 
 in any way to fulfil the prime requirements of the case, viz. the 
 complete protection of the hxxll from the action of the sea-water, 
 and causing the action of that sea-water to induce a constant 
 renewal and cleansing of the surface, whereby alone fouling can be 
 prevented and the corrosion of the hull avoided. Not even the 
 " enamelling," which is so beautifully done, is of the slightest use, 
 as it presents a permanent surface, and does not exfoliate ; besides 
 which the difference of expansion of the iron of the hull and the 
 enamel causes it continually to chip off. Most of the plans for 
 sheathing or protecting the hulls of iron ships seem to have been 
 originated with the view of their application to ships already/ con- 
 structed, and until 1863, when Mr. T. B. Daft, C.E., patented his 
 improved plan of constructing ships, so as to admit of their being 
 readily sheathed, this point seems to have been overlooked. In 
 order to apply sheathing to ships already built, it becomes needful 
 to attach a coating of wood, to which this sheathing is to be nailed, 
 and the difficulty they all labour under is that they are not com- 
 ponent parts of the structure of the ship, but are, as it were, 
 plastered on to the hull, and consequently easily damaged and 
 readily detached. 
 
 By the plan of Mr. Daft the hold for the sheathing nails is in- 
 corporated in the body of the vessel, and thus becomes a part and 
 parcel of it, placing the vessel and her sheathing in the same posi- 
 tion as a coppered wooden hull, exposed to similar casualties in 
 regard to stripping, &c. This plan increases the facilities for 
 sheathing, decreases the expense, and does not increase the bulk of 
 the hull by more than the thickness of the zinc sheathing used for 
 the purpose, besides making a flush surface, and a better job in all 
 respects. 
 
 Wood sheathing on the hull of an iron ship is a mistake. It is of 
 no use to prevent fouling ; it does not strengthen the ship ; it 
 becomes water soaked ; it enlarges the midship section, and conse- 
 quently does not increase the ship^s speed ; it is sure to be quickly 
 attacked and destroyed by worms ; in fact, it can only be at once 
 and unhesitatingly condemned, more particularly when it is 
 accompanied with the pernicious arrangement oi sheet copper or 
 yellow metal laid on it. 
 
 The cost of this complicated arrangement, viz. first giving the 
 ship a coating or two of red lead, marine glue, cement, or some 
 other delightful material, then a coating or sheathing of felt or 
 india-rubber, or both combined, then a coating of wood, and then 
 the sheathing of copper or yellow metal, is no small trifle, the 
 " Royal Sovereign " being estimated to cost £3000, which may be 
 looked on as thrown entirely away, first, because the plan is inefii- 
 cient J secondly, because it brings in the fatal objection of galvanic 
 action ; and thirdly, because it is eminently lacking in solidity and 
 
40 THE FOULING AND CORROSION 
 
 durability — points that should never be lost sight of in carrying 
 out such undertakings. 
 
 Zinc as a material for the sheathing and protecting of ships' 
 bottoms is a comparatively new application in this country^ for it 
 seems that, though patented in 1805, in 1848 there were only five 
 British ships on which it was known to be employed. So well 
 did it answer, however, that by the year 1850 there had been 300 
 ships sheathed in British ports, which number had increased in 
 1852 to upwards of 1000, and its increase still appears to be great. 
 Al] these vessels were of wood, however, and it was specially 
 requested that in applying this material to ships fastened with 
 copper, yellow metal, or iron bolts, layers of tarred felt should be 
 placed over them to prevent galvanic action destroying the zinc. 
 
 Zinc rolling mills seem to have been first started in the year 
 1834 at Dartford, in Kent, the machinery being made by Hall, 
 the well-known engineer of that place. 
 
 So little was the action of sea-water upon the copper or metal 
 sheathing of a vessel understood, that it was believed and asserted _ 
 to have kept clean by the oxide poisoning the zoophytes, &c., which 
 adhered to it; and when after some time the copper sheathing of 
 our ships of war was found to wear out, it was assumed that this 
 action ought to be stopped, and accordingly Sir Humphrey Davy 
 was applied to to introduce some mode of removing this evil. 
 
 Por this purpose he arranged iron " protectors ■" in connection 
 with the copper, which were applied to the " Magicienne,''' and it 
 was found that this plan only gave local protection, the greater 
 part of the copper oxidising as usual, only the parts contiguous to 
 the protectors being protected, and these portions were covered 
 with barnacles. These experiments, when carried further by means 
 of plates of tin, zinc, or other easily oxidizable metal, applied to 
 coppered ships, gave so perfect a protection that the ships' bottoms 
 became covered with barnacles and weeds, thus introducing a far 
 more serious evil than the one it was desired to remedy. It would 
 have been thought that these facts would have afi'orded excellent 
 grounds on which to form a theory of the mode in which copper 
 sheathing operated in removing fouling, and to have led to a 
 serious consideration of the subject; but it seems not to have 
 excited any attention, and the poisoning theory continued, and 
 still remains in force in some cases at the present moment. 
 
 There can be no doubt that, had proper attention been given to 
 the chemical action of metals in contact with sea-water, we should 
 not meet with the constant reference to the destructive action of 
 corrosion in our iron-clads and other, iron ships, which so con- 
 stantly appear in the columns of the daily press, nor would there 
 have been the enormous expense we now have to encounter from 
 the fouling of our large iron ships, and their consequent docking, 
 
OF IRON SHIPS. 41 
 
 cleaning, paintingj &c., and loss of time involved thereby, as due 
 consideration must liave led to the devising of some practical mode 
 of construction and sheathing by which all this would have been 
 obviated. 
 
 At the present moment this question is little understood by 
 many, and some have even gone so far as to compound a mixture 
 to be smeared over the copper, yellow metal, or zinc sheathing of 
 ships, to prevent the very action by which it keeps free from 
 fouling, namely, exfoliation ! and advance as an argument in its 
 favour that it will not wash off, and it completely arrests the oxida- 
 tion or wear of the sheathing, stating that the full weight of the 
 metal sheathing will be returned whenever it may be taken off, 
 and recommend its use on account of the immense saving that it 
 would effect. 
 
 Now, on analysing the subject and its economical results, the 
 following particulars are obtained : — First, a ship is sheathed with 
 copper, yellow metal, or zinc, in order that the loss of speed and 
 fouling found to ensue if they be not used may be prevented by 
 their exfoliation, and the hull saved from the attacks of worms. 
 Second, in order to prevent the copper exfoliating, and thus 
 keeping clean, and also the waste caused by that exfoliation, a 
 mixture or compo' is smeared all over the copper. Third, this 
 mixture or compo' is said to prevent fouling and oxidizing, and 
 also to prevent the attacks of the worm. Therefore it follows, if 
 this be true, that the compo'' will do all that the metals can, and 
 that consequently any metal sheathing is unnecessary. 
 
 Against any advantage that may be claimed for paints, compo', 
 &c., must be set the certain fact that they do not remove the 
 necessity for frequent docking, cleaning, and repaying, or plaster- 
 ing, with all their accompanying delays, expenses, and drawbacks ; 
 and it is certain that whatever weight of copper or other metal 
 sheathing they may prevent the waste of, over a period of say three 
 or four years, if their application be continued so long, it is equally 
 certain that the use of this protective compo', its docking, renewals, 
 and other expenses, will be found to far exceed any possible saving 
 that might be effected, and, in fact, to be more than the cost of re- 
 coppering or sheathing the ship at the end of such a period. 
 
 It is now a decided fact that no material which presents and 
 maintains a, permanent surface is of the slightest use in preventing 
 fouling or corrosion. The general ignorance of the action of cop- 
 per sheathing in keeping clean has caused the continuance of the 
 evil, and perpetuated a host of nostrums of the most expensive, 
 useless, and troublesome description, without in the slightest degree 
 abating the nuisance, added to which it has introduced and en- 
 couraged the useless and highly dangerous plan of placing sheet 
 copper or yellow metal on iron hulls, for no other reason than 
 
43 THE FOULING AND CORROSION 
 
 because they have been used, and keep clean on wooden hulls ; and 
 this too, in defiance of all that is known in regard to galvanic 
 action, its causes and results. Did any individual shipowner 
 choose to experiment on the readiest and surest way of destroying 
 his own iron fleet, there would not be much said about it ; but when 
 such absurdities are carried out on a national fleet, on which mil- 
 lions have been expended, and in which all are interested, it then 
 becomes a very serious matter. 
 
 There can be little reason to doubt that the constant advocacy 
 of copper or yellow metal as the only proper material for the 
 sheathing of iron ships arises from an ignorance of the action of it 
 in preventing fouling, it being almost the universal opinion that 
 the "poisoning" process is what causes it to keep clean. That 
 the poisoning theory is a fallacy the success of zinc (which is 
 admitted to be non-poisonous) when applied to iron, in keeping 
 free from fouling, sufficiently proves ; and where the mechanical 
 assistance to the process, viz. the friction caused by the ship in 
 passing through the water, which aids in rubbing off the exfoliation, 
 does not take place — for example, when the ship lies at her moor- 
 ings — a limited degree of fouling still takes place on the surface of 
 the copper or yellow metal, in spite of sufiicieut verdigris or poi- 
 sonous matter being on the surface, to give ample proof whether 
 the theory be right or wrong. 
 
 The action of copper in keeping clean is thus stated by the 
 'Engineer^ of December 21st, 1866: — "The beneficial action 
 which continuously keeps a copper bottom from sea-weed is evi- 
 dently due to a double process of exfoliation and of a generation 
 of a poison (verdigris) inimical to the development of organic 
 life." 
 
 The idea of copper keeping clean by the poisoning process killing 
 the zoophytes was held by Sir Humphrey Davy, and in order to 
 prevent what was then considered the unnecessary waste of copper 
 sheathing, by corrosion or exfoliation, he protected it by zinc or 
 iron. The experiment succeeded scientifically and thoroughly in 
 preventing exfoliation or loss ; but it failed to be a practical benefit, 
 inasmuch as the sheathing became covered with sea-weed, shell- 
 fish, &c., which it did not do when the copper exfoliated, conse- 
 quently his plan had to be given up, to the great mortification of 
 Sir Humphrey. 
 
 If this idea of poisoning the weeds, barnacles, polypi, and other 
 annoyances which seem to have such great " proclivities " for ships' 
 bottoms, were correct, there can be no doubt that such action would 
 take place just as surely and well whether the ships were at anchor 
 or under way; and there would not then be found the constant 
 records of the failures which greet all the multifarious attempts 
 ■which have been and are yet made to obtain success by this pro- 
 
OP IRON SHIPS. 43 
 
 cesSj whether sdught for by the application of compositions, 
 plasters, or by the application of the metal in sheets. 
 
 The fallacy of the " poisoning " theory will be proved further on 
 in this work from the results of actual experiments ; and it is well 
 known that all the "compositions^' compounded in accordance 
 with this theory have totally and utterly failed when tried in 
 actual use. 
 
 It is a curious fact, that but little attention has been given to 
 investigate the action required in whatever is used as a means for 
 preventing the fouling of ships' bottoms ; but it has at once been 
 assumed that the action required is that of poisoning, and on 
 this hypothesis nearly all the inventors have proceeded. The 
 results will be found recorded in the chapter on Fouling. 
 
 It was stated at a .late meeting of the Scottish Shipbuilders' 
 Association, by the chairman, that an iron plate had been coated 
 in squares with four of the best-known " anti-fouling " composi- 
 tions, and, after having been submerged for some months, was 
 raised for examination. The plate was found covered with barnacles, 
 and the most ridiculous part of the affair was that the biggest 
 barnacle of the' lot, " the great grandfather of all barnacles," had 
 •stuck himself in the very centre of the plate, right on the point 
 where all the four compo's joined, as if to show his utter contempt 
 for and ridicule of the useless and worthless plan of " poisoning " 
 them. 
 
 The royal mail-steamer " Atrato" had one side coated with a pre- 
 paration of copper, its use being propounded in accordance with the 
 " poisoning " theory, and when docked for examination the green 
 copper composition was found to be covered with a coralline incrus- 
 tation and patches of rust or oxide. 
 
 The "Valiant," in 1865, had one side coated with a preparation 
 of copper, and when examined, in about five months afterwards, 
 was found to have this " poisonous " composition thickly coated 
 with barnacles, sea-weed, &c. 
 
 The " Orontes," iron troop-ship, was coated with a poisonous 
 anti-fouling composition containing copper, and when examined 
 some time afterwards was found to be, under her counter 
 and in the run of her after portion of the hull, thickly encrusted 
 with barnacles ; and the bottom was dotted all over with patches 
 of rust, the rivet-heads in many places showing evident signs of 
 being affected by the copper contained in the anti-fouling compo- 
 sition. 
 
 In the 'Times' of January 17th, 1865, it was stated that the 
 " Royal Oak " iron-clad, which is sheathed with Muntz's metal, . 
 was docked, after six months' service, in the Mediterranean, and 
 " her bottom was found to be foul beyond conception ; masses of 
 
44 THE FOULING AND CORROSION 
 
 animals, zoophytes, corallines, &c., all so encrusted with weeds in 
 one mass that sharp scrapers will alone detach them." 
 
 It is stated that one of H. M. ships, which had been lying quiet 
 at Bermuda for some time, had layers of oysters, &c., upwards of 
 a foot thick, on her copper sheathing, the copper being actually 
 taken up by the animal in the formation of its shell as a carbonate 
 of copper, the shells of the inner layer of oysters being all of this 
 beautiful green colour throughout. Some of these shells were a 
 short time since in the possession of the storekeeper of the Royal 
 William Victualling Yard at Plymouth. 
 
 In another case the interior of one of the large globes of 
 Griffith's screw propellers, which in the navy are made of gun- 
 metal, was found on examination to be completely filled up with 
 full-grown mussels and barnacles, although the aperture through 
 which the spawn had entered was not more than half an inch in 
 area. Where, then, is the " poisoning " theory in all these 
 instances ? 
 
 The French Government seems to maintain a perfect indifference 
 to the fatal injury resulting to the iron hulls and armour plates of 
 the iron-clads from the use of copper or yellow metal sheathing, 
 in spite of the remarks of M. Becquerel, their eminent chemist/ 
 whose researches have shown that, by the employment of zinc for 
 sheathing iron vessels in place of copper or yellow metal, the iron 
 may be kept free from fouling, and also preserved instead of in- 
 jured, which is of the greatest importance. 
 
 It is curious to see the constant and persevering attempts which 
 are made, both in England and France, to use copper or yellow 
 metal for sheathing iron ships, and the schemes which are tried to 
 prevent its certain and fatal action, whilst any endeavour to give 
 zinc an equal trial is most studiously avoided. It would seem as 
 though there were some fascination, or important advantage to be 
 gained by trying the former, which does not exist, or has not been 
 discovered in the case of the latter. But it remains to be seen 
 whether the tax-paying public wiU much longer permit these useless 
 and dangerous experiments to be tried on the costly iron-clads. 
 
 M. Roux, a captain in the French Imperial Navy, seems to have 
 succeeded in convincing the naval authorities of that country that 
 copper can be readily applied to iron hulls without causing any 
 damage 1 It is stated in the ' Engineer' of December 21st, 1866, 
 that " It was M. Dupuy de Lome who first suggested to Captain 
 Roux the idea of applying copper directly on the iron shell of the 
 vessel, observing that the efi'ects of any galvanic current were not 
 to be feared, ' as long as the plan employed absolutely prevented 
 the presence of sea-water at the points of contact of the two 
 metals.' " 
 
 The same journal goes on to say that " The next steps were. 
 
01' IRON SHIPS. 45 
 
 therefore^ to find a mode of isolating the copper from the iron, and 
 some mechanical plan for securely fixing the copper sheets." In 
 order to obtain the former, it is said that he coats the iron with 
 red lead, over which he places a composition, and on this composi- 
 tion he places the copper. For the latter, viz. "a mechanical 
 plan for securely fixing the copper sheets," it is stated that the 
 inventor " professed to drill into the iron a small conical hole five 
 millimetres deep and six millimetres (about 5 inch) in diameter, 
 and then to spread out a suitable rivet in this hole. By this means 
 any defects resulting from the drilling of the hole practically dis- 
 appeared, the soft rivets completely filled up any irregularities, and 
 were firmly clenched in." 
 
 Of this plan the "^ Engineer' remarks, "It is certain that the 
 process has a simple and rational look, whatever may be the ulti- 
 mate results." 
 
 Now, there are generally about 120 holes in a sheet of copper as 
 used for sheathing wooden ships, and a ship of 400 tons generally 
 requires 1140 such sheets. If, therefore, the same proportion holds 
 good for iron ships, it follows that the amount of holes drilled into 
 the hull for the reception of the " soft rivets " will amount to 
 something considerable (in the case of a 4000 ton ship, on one plan 
 of sheathing, there are 45,663 holes at 3d. each = £570 15s. 9d.) ; 
 but as it is only "drilling holes," there can be no doubt of the 
 " simplicity " of this part of the process. 
 
 It will be interesting to examine the mode in which the experi- 
 ments with Captain Roux's plan were carried out, from which 
 sufficient results were obtained to satisfy those in authority of its 
 feasibility and advantages, and also to prove to them that the 
 destructive action of copper on iron does not present any real 
 difficulty in actual use. 
 
 We are told that the " first trial was made with a large flat- 
 bottomed iron boat, the plates of which were very much corroded. 
 After a service of nine months at sea, seven of which were passed 
 in active service at the arsenal of Toulon, the boat was taken on 
 land and examined by a commission and M. Dupuy de L6me. No 
 vegetation was found on the outside, and only one copper sheet 
 above the water-line was found injured, probably by scraping 
 against another vessel; on stripping more of the copper sheets the 
 iron Vas found in a perfect state of preservation, without oxida- 
 tion, and all the rivets in a good state." 
 
 We are further told that, " in consequence of this success, the 
 iron-plated corvetice ' La Belliqueuse ' was placed in M. Roux's 
 hands to be sheathed by his process before beginning a long cruise 
 in the Pacific. He expects that the copper sheathing will last 
 twelve years, as his pi an is based upon the principle that the copper 
 protects the composition, the composition the red lead, and that. 
 
46 THE FOULING AND CORROSION 
 
 lastly, the red lead protects the iron." Since the sheathing of 
 " La Belliqueuse/' M. Roux has been ordered a few weeks ago to 
 apply his sheathing to the iron-plated frigates " La Savoie " and 
 " La Revanche." 
 
 A few moments' reflection will show how insufficient such a plan 
 of trial is, and how well calculated to cause error. The boat, we 
 are told, was " seven months in active service at the arsenal at 
 Toulon;" when she was hauled up and examined the iron was 
 found " in a perfect state of preservation, without oxidation." 
 
 Now, here were conclusions drawn from the results of circum- 
 stances which never exist in the case of large ships in active 
 service, and it does not seem that it ever occurred to any one that 
 this was the case. This flat-bottomed boat, we are told, was 
 coppered " above the water-line ; she was employed at the arsenal 
 at Toulon," and consequently in smooth water, not being subjected 
 to the constant washing of the water over the copper and the iron 
 hull, as would be the case of a large ship at sea in active service, 
 and which it is found wholly impossible to prevent. 
 
 It is this contact of the water with the copper or yellow metal 
 and the iron hull which causes the destructive galvanic action to 
 be set up. Keep the three from contact and no result follows, but 
 it matters not how perfectly or completely insulation may be 
 secured between the iron hull of the ship and the copper sheathing 
 by the interposition of non-conductors, if when the ship is afloat 
 the water is allowed to produce contact between them by washing 
 indifferently over both. 
 
 It has actually been proposed to drill the skin of an iron ship 
 full of holes, and tap copper bolts or studs into them with the view 
 of riveting on copper or yellow-metal sheets, interposing a sheet of 
 iron and some insulating material between; and it is gravely 
 asserted that this will prevent the water following or obtaining 
 access to the skin of the ship, and thus prevent the corrosion and 
 galvanic action between the different metals and the water which 
 would otherwise take place ! 
 
 This ingenious, cheap, and thoroughly practical arrangement, 
 which is perfectly in accordance with the knowledge required to 
 devise an arrangement to set up galvanic action to destroy the 
 positive or weaker metal, namely, the iron, has actually been 
 approved of and pronounced extremely simple, in the following 
 words : — "Altogether, this is the simplest and apparently the most 
 efficient form of sheathing for iron ships that we have seen "\ 
 
 It has been well and truly remarked that " It should be the 
 function of engineering papers to explode all palpable bubbles, and 
 to guide public opinion aright in matters beyond popular analysis 
 and appreciation ;" otherwise " will the public lose confidence in 
 those blind guides by whom they have been so much misled." 
 
OF IRON SHIPS. 47 
 
 The " Caledonia," iron-cased ship, has been sheathed with teak 
 three inches thick, and this covered with a new description of metal 
 sheathing, being copper on one side and pewter on the other, the 
 idea being that n,o galvanic action prejudicial to the iron can be 
 excited by this arrangement. 
 
 The " Zealous " has been sheathed with teak planks three inches 
 thick above the water-line and four inches thick below it. In 
 carrying out this plan it has been determined in future to bolt the 
 planking directly on the plates, to avoid weakening the planks by 
 the grooves they formerly cut in them. 
 
 Ever since the fouling and corrosion of the hulls of iron ships 
 showed the necessity of preventing them by sheathing, it has been 
 a desideratum to obtain a simple, practical, and efficient mode of 
 attaching the plates of metal or sbeathing to the iron hulls ; and 
 though many plans have been patented and proposed, all more or 
 less ingenious or objectionable, none can at present be said to be in 
 use or capable of fulfilling the requirements of the case in a satis- 
 factory or efficient manner. 
 
 In 1863 Mr. Mallet, who is considered by some people as no 
 mean authority on such matters, said that " any attempts at coating 
 an iron ship directly with any metal sheathing is quite out of the 
 question ; the mechanical difficulties are insuperable. You cannot 
 attach sheathing firmly to the skin of an iron ship in any way, but 
 you injure the strength and diminish the safety of the ship enor- 
 mously. If it were possible to get the hull of an iron ship into a 
 condition that it would not corrode at all, there would no longer 
 be any difficulty about preventing it from fouling at all." 
 
 It may be that, on examining Mr. Daft's plan of constructing 
 iron ships and vessels and sheathing the same, Mr. Mallet will be 
 disposed to alter his extremely decided opinion, and, as a mechanic, 
 recognise the truth of the saying that " there is no finality in en- 
 gineering," before he again ventures to pronounce so decided and 
 dogmatic an opinion on a matter which in a twelvemonth after- 
 wards is fully and completely solved in the two points, one of which 
 was " quite out of the question," and the " mechanical difficulties " of 
 the other were " insuperable." 
 
 Numerous attempts have been made to attach the metal used in 
 sheathing to the bottoms of iron ships, and "sticking" them on 
 by means of some adhesive material has been a tolerable favorite ; 
 next has been that of drilling through the hull or skin of the ship a 
 quantity of holes, through which the bolts holding on the wood 
 sheathing passed, on which wood the sheathing metal was nailed ; 
 next, ribs or ridges of iron were attached to the hull, vertically or 
 horizontally, and the wood sheathing wedged or jammed in between 
 them, and the metal sheets" put on this ; in fact, several modes 
 have been proposed or patented for this purpose, but, so far as ex- 
 
48 THE FOULING AND CORROSION 
 
 perieace shows, have met with but a very limited amount of 
 patronage. All the plans for huilding a wooden ship on an iron hull, 
 and then coppering, yellow-metaling, or sheathing it, are but very un- 
 satisfactory and objectionable plans, increasing the midship section 
 of the ship without adding to the strength of the vessel, and bring- 
 ing a metal of a superior galvanic power into close connection, by 
 means of damp wood and water, with a weaker one. 
 
 We often hear it dogmatically asserted that zinc is of no use for 
 sheathing iron vessels, because where it has been used on wooden 
 ones it soon fails, and this from the formation of an oxide or 
 carbonate which is so hard as to turn it into a permanent surface. 
 That this is true there is not the slightest doubt, and the author 
 has seen wooden ships sheathed with zinc in a most surprisingly 
 foul state. A little consideration of the subject, however, would 
 have shown that this failing arises from the lack of the very cir- 
 cumstances required to prevent it, viz. exfoliation, which, it may be 
 observed, is most readily and surely obtained, and to any required 
 amount, when the zinc is placed on the hull of an iron ship. 
 
 Prior to 1833 the copper used on the bottoms of the ships of the 
 Royal Navy did not waste at a greater rate than one ounce per 
 square foot per annum, whilst subsequent to this the average loss per 
 sheet was four ounces per square foot per annum. There can be 
 little reason to doubt that this was owing to the employment of 
 iron fastenings, and that galvanic action took place between the 
 iron bolts and the copper sheathing, thus preventing the ex- 
 foliation of the copper and destroying the iron, causing the ship to 
 become "nail-sick." 
 
 When, however, copper and yellow-metal fastenings were intro- 
 duced and iron given up, the action of the sea- water on the copper 
 sheathing had uninterrupted sway, and the copper exfoliated at 
 the increased rate mentioned, causing great excitement amongst 
 the Government authorities at this increased waste, and no small 
 amount of inquiries and investigations were made to find out the 
 " reason why ;" but it was finally concluded that it was the fault 
 of the copper, which proved itself not to be so good as that formerly 
 used ! 
 
 Mr. Scott Russell remarked at the Institution of Naval Archi- 
 tects, in 1866, "The great merit of copper is that it decays. You 
 all know how rapidly it wears out. And what do we pay the price 
 for it for? We pay the price of copper in order that by its rapid 
 decay, and its passing ofiF and taking the barnacles with it, we may 
 keep our ships pure and clean.'' 
 
 The general idea in regard to the sheathing of ships seems to 
 have been that it ought not to waste away, and that any tendency 
 to this was an evil that ought to be checked. This wish to " eat 
 the cake and have it too " is very bad policy, and shows a complete 
 
OF IRON SHIPS. 49 
 
 ignorance of the mode in which the sheathing acts ; for the fact 
 has been patent to any one that took the least trouble to know 
 the " reason why," that the sheathing must " perish," in order to 
 " keep clean ;" and that if it does not perish the sheathing is pre- 
 served, but at the expense of a constantly dirty bottom to the ship. 
 
 It is now known to all who have studied the subject that the 
 cause of copper, yellow metal, zinc, and other metallic alloys placed 
 on a ship''s bottom, keeping clean and free from fouling, is the ex- 
 foliation of the metal and the constant renewal of the surface caused 
 thereby, through which the adherent matter is, as it were, sent 
 adrift, by the friction of the water against the metal sheathing 
 washing ofiF the exfoliated parts or films. From this it will be evi- 
 dent that there is just such a rate of exfoliation as will secure this 
 great and important advantage without causing too rapid and un- 
 necessary a destruction of the metal, which it is inost important 
 should be made to last as long as possible, provided it does not in- 
 troduce any other disadvantage, or interfere with the proper carry- 
 ing out of the end for which it is applied. 
 
 A vessel with an iron hull, cased with' wood and sheathed with 
 copper or yellow metal, is in a state of perpetual risk and danger, 
 as a blow, grounding, galvanic contact of the two metals, or the 
 detachment of the sheathing, must render her docking an immediate 
 necessity, unless it be preferred to run the risk of allowing galvanic 
 action and corrosion to take place. In fact, a ship so circumstanced 
 can only be looked on as a huge galvanic battery, always ready to do 
 mischief, and rapidly destroy the positive or weaker metal, viz. the 
 iron of the hull of the ship, when sufficient metallic contact shall be 
 produced, and always in operation through the contact afforded 
 by the water or dampness in a less rapid degree. 
 
 Rear-Admiral Sir F. E. Nicholson, C.B., remarked, at the Royal 
 United Service Institution, on the 20th March, 1865, that in the 
 "Caledonia" "a belt of wood was originally placed between the 
 Muntz's metal on her bottom and her iron plates. It was well known 
 that damp wood is a partial conductor ; still it was supposed that 
 this would be a better plan than bringing the Muntz's metal right 
 under and in contact with the armour plates. If that had been 
 done there is no doubt that the armour plates would have been 
 ruined." 
 
CHAPTER V. 
 
 FOULING. 
 
 Fouling, or the adherence of barnacles, seaweed, zoophytes, 
 and other matters, to the bottom or immersed portion of a ship's 
 hull, constitutes a most expensive and objectionable feature in iron 
 ships, and one which has employed an enormous amount of time, 
 ingenuity, and money, in essaying its removal. The enormous 
 number of patents which have been taken (some 300 or more in 
 number), and the numberless experiments which have been made 
 to prevent fouling and corrosion in the hulls of iron ships, must be 
 taken as proofs both of its extremely difficult solution and the 
 great desirability of its being achieved. 
 
 By fouling, the speed of a ship is diminished, and delay on the 
 voyage encountered, whilst, if it be a steamship, there is the 
 increased consumption of coal, with a less distance done per ton, 
 increased wear and tear of boilers and machinery, and the increased 
 risk of delay from breaking down ; and this involves the necessity 
 of going into port, docking, cleaning, painting, or coating, and the 
 great expense and loss of time incurred in carrying out these 
 requirements, whilst if it be a ship of war, to all these drawbacks 
 must be added that of having to return from a distant station, the 
 loss of its services whilst away, and the delay caused in getting 
 back to the station again, with the expenses in so doing. 
 
 In order to prevent a ship proving a loss to an owner, " it should 
 be kept moving," or, in other words, " earning money ;" and so 
 long as this can be done many will put off the docking and cleaning 
 until they are literally obliged to do it, or there are some repairs 
 of hull or overhaul of rigging which would enable one operation to 
 serve for both. 
 
 The cost and loss of time involved in cleaning an iron ship and 
 keeping her in proper order are very great ; and though some ves- 
 sels may be kept afloat and at work when they are in such a state 
 as ought to ensure their cleaning and overhaul, still this does not 
 prove that the cleaning is unnecessary or should not be done ; and 
 it is well known that many will prefer a loss of speed to frequent 
 
THE FOULING AND CORROSION OF IRON SHIPS, 51 
 
 docking and cleaningj even although they may admit that such 
 cleaning ought to be done. 
 
 As the value of a ship must in a great measure depend on her 
 speed, that is, on the quickness of her getting goods to market and 
 the number of voyages she makes in a given time, it is imperative 
 that she should not be delayed on her course by shell-fish and 
 seaweed attaching themselves to her, nor by being kept in dock 
 for their removal. It is often found that a ship loses 25 per cent, 
 of her proper speed by this cause, besides a considerable time by 
 going into dock, when foul, to be made clean again. 
 
 Iron ships are generally built with lines to obtain speed, but the 
 very material used, and the mode in which it is employed, are 
 found to be the most certain means of losing it. Iron, with- 
 out some mode of preventing it, fouls rapidly, and this fouling 
 decreases the speed in proportion to its amount, whilst at the same 
 time the expenditure is increased without one corresponding or 
 proportionate benefit being obtained. 
 
 The numberless patents for preventing fouling and corrosion of 
 iron ships show how generally these evils are admitted, and the 
 necessity felt to exist for removing or mitigating them ; but on 
 examination it will be found, as a rule, that but little knowledge of 
 the conditions involved, or the best mode of most practically ful- 
 filling them, have been exhibited in these attempts. 
 
 In spite of the numerous and continued examples of the great 
 expense, loss of time, loss of speed, and other serious and fatal 
 drawbacks caused by fouling, there are still people to be found 
 who attach no importance to it, and maintain that it is only in 
 peculiar instances that it has produced any annoyance. 
 
 Mr. Lamport, at the Institution of Naval Architects, in 1864, 
 observed — " Some gentlemen made light of the question of fouling. 
 I took up the ' Shipping Gazette ' the other day, and looked at all 
 the ships overdue from China, the longest average voyage we have. 
 They were all of them over six months on a voyage, which is from 
 two to three months more than they ought to be. Out of seven so 
 overdue six are iron. Will any gentleman tell me that an iron 
 ship can be cheap, can be profitable, if she runs the risk of being 
 from two to three months overdue V 
 
 Mr. Grantham, C.E., said, in 1861, at the Institution of Naval 
 Architects, speaking of iron ships — "Many attempts have been 
 made to keep these ships clean in tropical climates, and it is most 
 essential that those which have to go upon foreign stations for a 
 period of three or four years at a time should be kept clean. A 
 ship, with all our present knowledge, sent on such an expedition, 
 in twelve months will be almost useless. I have heard of one 
 instance in which the screw port was so choked with barnacles 
 that they could hardly get the screw to start.^' 
 
52 THE FOULING AND CORROSION 
 
 Fouling involves an enormous loss of money and time, and the 
 following heads will he found to comprise the chief divisions : — 
 1. Docking and undocking. 2. Labour of cleaning bottom and 
 putting on coating. 3. Cost of coating materials. 4. Wear and 
 tear of ship's bottom when scraped or cleaned in being prepared for 
 coating, including the injury done to the rivet-heads by scraping. 5. 
 Attendance of officers at docking and undocking. 6. Steam-vessels 
 at ditto. 7. Unloading and loading stores. 8. Stowing and un- 
 stowing stores. 9. Wages of unemployed crew. 10. Loss by 
 reduced rate of speed. 11. Loss of service of ship, officers, and 
 crew, while in dock having the bottom scraped, &c., &c. fourteen 
 days each six months. 
 
 It is said that the Peninsular and Oriental Steamship Company 
 expend some j670,000 a year in keeping the bottoms of their vessels 
 clean and free from fouling, all of which would be saved were this 
 serious drawback of fouling overcome. 
 
 If the amount of money actually expended and loss of time 
 incurred in keeping clean the bottoms of our iron ships, either in 
 the Royal or the Merchant service, could be obtained at the close 
 of each year, and put on record, there can be no question but that 
 the residt would be beyond conception, and could not fail to cause 
 far more attention to be given to its prevention than has appa- 
 rently hitherto been the case: 
 
 So far people seem to have come to the conclusion that fouling 
 cannot be prevented, and is an evil inseparable from the use of 
 iron ; but that it is so, or ought to be so, is quite another question, 
 and there can be no doubt but that the constant failures of the 
 innumerable nostrums so frequently brought forward as perfection 
 have in no small degree contributed to perpetuate this state of 
 tilings, and disposed people to fancy that prevention in a perfect 
 manner is quite unattainable, and that nothing further need be 
 desired. 
 
 It is stated that the '^ Solferino," "Provence," "Normandie," 
 " Invincible," " Gloire," and " Couronne," six of the iron-plated 
 fleet belonging to the French Imperial Navy, have had to pass 331 
 days in dock since the 1st day of January, 1865, up to the 8th of 
 March, 1866, which gives an average of fifty-five days each during 
 a period of little more than fourteen months ! 
 
 Mr. Lamport asked, at the Institution of Naval Architects, in 
 1864 — " I put it to any owner of an iron ship whether he would 
 not willingly pay the cost of coppering to avoid the drawbacks of 
 fouling ?" 
 
 Mr. Grantham said, at the Institution of Naval Architects, 
 1865 — "The one and the only difficulty which stares us in the face, 
 and I have spoken about it so often that I do not like to say much 
 about it now, is the impossibility at present of keeping our iron 
 
OF IRON SHIPS. 53. 
 
 ships clean at the bottom. I believe I may say with safety that 
 every possible objection has been long ago overcome, except that 
 one diflSculty of fouling." 
 
 Mr. Mallet remarked, at the Royal United Service Institution, 
 in 1862 — " The importance of the subject I think it would be 
 difficult to overrate; for highly important as the corrosion and 
 fouling of iron ships has been at all times to the mercantile marine 
 in a money sense, it becomes of far more vital importance now that 
 iron ships are certain to be applied for war purposes ; for if it be a 
 fact that a war ship sent to sea, after some six or eight weeks loses 
 a mile an hour of her speed from alteration of the surface of her 
 immense hull, or, as we may call it, from fouling — ^if a vessel so 
 circumstanced be caught by a clean ship of the enemy that has got 
 the mile an hour still, the former is taken at a disadvantage which 
 nothinff can make up for, and so the mere state of her surface 
 determines whether she can keep the seas or not. Hence this 
 question of fouling has become a national one." 
 
 Captain Selwyn says — " Speed is universally acknowledged to be 
 one of the first desiderata for every man-of-war, and that it is an 
 absolute necessity for the weaker ones. It is no less true that if 
 we are to avail ourselves of the thinner and lighter material — steel 
 — in the construction of ships, special care must be taken that no 
 injurious galvanic action which can be avoided operates to reduce 
 its original strength." 
 
 Lord Clarence Paget, in commenting on the serious drawbacks 
 caused by the fouling of our iron-clads, and the foul state they 
 were constantly in, spoke of the importance of some means being 
 obtained by which it would be prevented, and described these 
 vessels to be " always as foul as lawyer's wigs \" 
 
 The rapidity with which fouling takes place in the spring and 
 summer seasons can hardly be conceived by those unacquainted 
 with the subject ; and where the circumstances and conditions are 
 favorable to its progress, it becomes a serious and annoying, if 
 not dangerous, evil, and one which requires the most unremitting 
 care and attention to prevent the occurrence of serious results. 
 
 It is related by some of the Southampton pilots that they have 
 found it necessary during the spring and summer seasons to lay 
 their vessels on shore at least once in every fortnight, to scrub oflF 
 the weeds and slub which form on their bottoms. 
 
 Some of the St. Mawes' pilots, near Falmouth, have stated that 
 they have invariably been obliged to clean the bottoms of their 
 vessels once every fortnight, and if left for a month great difficulty 
 has been found in removing it, the accumulation having become so 
 thick and so strongly adhesive. 
 
 The "Monarch" steamship, belonging to the Electric and Inter- 
 national Steamship Company, required docking every six months, 
 
54 THE FOULING AND CORROSION 
 
 and was found each time to be completely covered with vegetation, 
 barnacles, shell-fish, &c. 
 
 One captain of an iron ship says — " When I left London the 
 bottom was coated with red lead and tallow, and upon my arrival 
 at Shanghai, after a long voyage of 150 days, the bottom was so 
 foul that I was compelled to have the ship docked. I am con- 
 vinced common paint and tallow are useless, either for preserving 
 the ship from rust or in keeping clean/' 
 
 The Peninsular and Oriental steamer " Northam " got so foul 
 on the voyage from Sydney to Point de Galle that her speed fell 
 off considerably, although coated in dock previous to leaving 
 Sydney ; and having no time to dock again at Ceylon, the evil 
 increased so fearfully on the return voyage that several days were 
 lost by the reduction of speed. 
 
 On« of the commanders of the Peninsular and Oriental Company 
 writes — " I have been in the habit of taking out several iron steamers 
 before to distant parts of the world, coated with different composi- 
 tions, but invariably found that their bottoms were fouled with 
 weeds and .barnacles before we had been six weeks at sea, much 
 retarding the latter part of the voyage, notwithstanding we had 
 taken opportunities of scrubbing them off as far down as we could 
 reach." 
 
 The General Screw Steam Shipping Company required to dock 
 their Cape steamers every voyage to clean and re-coat. 
 
 Admiral Sir E. Belcher, C.B., has stated that a copper-bottom 
 frigate, after lying four or five months in the Medway, will in this 
 short period accumulate from four to five tons of mussels, &c., 
 on her sheathing. 
 
 It is said that when the " Royal Oak," an old sailing man-of- 
 war, was broken up at Bermuda some few years since, the layers 
 of oysters, one over the other, were so thick that the weight was 
 estimated at upwards of eighty tons ! 
 
 The iron troop ship " Adventure," when examined, after nine 
 months' absence from England, was found to be encased with 
 oysters and very foul, in spite of a smearing and plastering before 
 her departure. 
 
 The 'Times' of the 1st August, 1864, relates that "The 
 " Dromedary" iron steamship, in Her Majesty's service, is just uu- 
 docked at Woolwich, having returned from the Mediterranean, 
 with an incredible amount of seaweed and barnacles attached to 
 her, which have adhered in spite of all the inventions tried and 
 said to prevent them." 
 
 The 'Times' of the 23rd of September, 1864, stated that, 
 "Owing to the length of time the " Achilles " has been lying in the 
 river, her bottom has become exceedingly foul, and the examina- 
 tion of her hull by one of the professional divers has resulted in 
 
OP IRON SHIPS. 55 
 
 the discovery that the whole of her bottom is completely covered 
 with marine insectsj harnacles, and seaweedj some of the last being 
 as much as two feet in length. The bottom of the " Achilles/' it 
 may be remeraberedj was coated over with Hay's anti-fouling com- 
 position before the frigate was undocked, and, as she has been 
 lying some nine months in Chatham Harbour, a pretty correct 
 estimate may be formed of the state our iron-clads will be in if 
 detained only for a very short time in tropical waters. In the 
 case of the " Achilles " fully two knots an hour may be deducted 
 from her speed if sent to sea in her present condition.^' 
 
 Captain Fishbourne stated that when he was on the coast of 
 Africa an iron whaler came out from England ; and though she had 
 only left six months, and been cleaned as well as they could at sea 
 with long brooms and ropes under her bottom every month, she 
 had long grass and barnacles of immense size attached to her, in 
 consequence of which she was not safe, as she would neither sail 
 nor steer, and was not manageable. 
 
 When the " John Garrow " iron sailing ship returned from a 
 voyage to Bombay, on which she was absent twelve months, she 
 was found exceedingly foul and covered with a dense mass of 
 barnacles ; in consequence, she made a very tedious voyage. 
 
 The " Triton " iron steamship was found, when docked at Key- 
 ham, to be nearly covered with oysters of an enormous size, the 
 interstices being filled up with zoophytes and large acorn barnacles 
 as big as egg-cups, one overlapping the other. 
 
 The ' Times ' of November 18th, 1864, relates that though the 
 " Achilles " iron frigate " was covered over before her launch with 
 the anti-fouling composition of Mr. Hay, the Admiralty chemist, 
 so foul had the bottom of that vessel become while lying in Chatham 
 Harbour preparing for sea, that in the run made from Chatham to 
 Devonport her speed fell off more than three knots per hour from 
 her steaming rate on the occasion of her official trial at the Maplin 
 Sands. When docked at Devonport the bottom was not only foul, 
 but many of the plates were left completely bare of composition, 
 and white corrosion had in many instances eaten away the plating 
 to a depth of one sixteenth to one tenth of an inch." 
 
 The 'Times' of the 25th January, 1865, reported that "The 
 " Royal Oak^s " bottom was found to be foul beyond all conception. 
 Immense quantities of zoophytes, weed, and coralline flourished in 
 the wildest profusion, and so hard had the little insects formed 
 their habitations that nothing short of a general scraping with 
 short scrapers would remove the incrustations, the result of barely 
 six months^ accumulation. Whether this rapid growth is due to 
 the Muntz's metal with which the ship's bottom is sheathed, or the 
 result of some general galvanic action, is hard to conjecture ; but 
 what another grand field for the experimentalists !" 
 
56 THE FOULING AND CORROSION 
 
 In the 'Times' of 21st June^ 1865, is the following extract from 
 the letter of their Malta correspondent : — " The " Resistance/'' 16, 
 iron-clad, is still in dock, having her bottom cleaned and coated. 
 On being left dry it is said that no less than twelve inches of grass 
 were found attached in some parts, although she had been hogged 
 within a month." 
 
 In the ' Times ' of 3rd November, 1865, and the ' Mechanics' 
 Magazine' of 10th of November, 1865, is the following account of 
 the state of the " Agincourt" ; — "The condition of the "Agin- 
 court," 26, at Devonport, has created considerable surprise in the 
 minds of the officers of the dockyard and others. About six weeks 
 since she was removed from the Prince's Dock, after having been 
 coated a second time with Hay's anti-fouling composition, and 
 was placed alongside the shear-hulk in Hamoaze, where she 
 received her five iron masts and was otherwise prepared for pre- 
 liminary trial of her engines, which took place on the 12th ult. 
 On Monday last the "Agincourt" was replaced in Prince's Dock, 
 and as the water was pumped out her bottom below the line of 
 flotation looked, as one of the artisans described it, ' like a field of 
 grass,' so regular was the growth of the weeds. Some were 
 nearly two inches long, and it extended from stem to stern and 
 down to the keel. It is supposed that if no composition had 
 been applied, vegetation could not have advanced to the same 
 extent." 
 
 The French iron-cased frigate "Invincible " had not been docked 
 for ten months, and when taken in her bottom was in a most sur- 
 prisingly dirty state. The copper was covered with a thick mass 
 of marine vegetation, a sort of white coral, and many kinds of shell- 
 fish formed a stratum which completely hid the sheathing, and was 
 five centimetres or nearly two inches thick over certain parts. There 
 were also in certain places patches of oysters, which firmly adhered 
 to the sheathing. There were not less than ten tons of vegetable 
 matter or fouling removed from the bottom. 
 
 When this vessel was tried after her completion in 1862 she at- 
 tained 13*5 knots under full steam, with 53 to 54 revolutions of the 
 engines. In April, ten months after she was undecked, she was 
 tried under full steam, the weather being calm and the water smooth, 
 when her greatest speed was 9'8 knots with the engines making 
 515 revolutions. After having had her bottom cleaned she was 
 again tried, when her speed was found to be 13*2 knots with the 
 engines mailing 53 revolutions, 
 
 The " Taureau," another Trench iron-clad, was found to have 
 fouled in a very short time, for, having been undocked on the 17th 
 November, 1865, and examined on March 15th, 1866 (four months), 
 a quantity of heath-like vegetation was found along the water-line 
 and below it, which was found to be swarming with young mussels 
 
OF lUON SHIPS, 57 
 
 and under the bottom was found a great quantity of little shells 
 about the size of a pin's head, and there was also a great quantity 
 of slime of a green colour, and tolerably thick. 
 
 One iron ship of nearly 800 tons register, which had been eight 
 months in a warm latitude, had thirty cartloads of barnacles (an 
 estimated weight of twenty-eight tons) removed from her bottom, 
 an encumbrance which could by no means have improved her speed 
 or sea- going qualities. 
 
 The inspector of machinery to the East India Company at Bom- 
 bay has stated that when the " Indus " steamer was taken into 
 dock at that port he took barnacles off the bottom twelve inches 
 thick and eighteen inches long ; and he also mentioned that the 
 " Nemesis " was a mass of barnacles upon the bottom. 
 
 The superintendent of the Peninsular and Oriental Company at 
 the same place says — " Between Bombay and China no ship should 
 be longer than/owr months without examination. The fouling com- 
 mences immediately after undocking. To maintain the regularity 
 of a mail service, four months is the outside limit that an iron ship 
 should run without cleaning and painting on the Bombay and China 
 line. The " Pottinger " iron steamer, which left England in Eeb- 
 ruary, 1847, to perform a voyage to India round the Cape, was 
 docked at Bombay in September. The bottom was very foul ; the 
 barnacles were six inches long, in large clusters. In the run a 
 second layer had begun to form. The " Pekin,'' which left England 
 in February, 1847, was docked at Bombay in October. I can com- 
 pare her to nothing else than a half tide rock. The barnacles were 
 nine inches long, the second strata being complete, with a feathering 
 coral formation sprouting from cluster to cluster. The stench from 
 the animal matter was so great that no one could remain on board 
 at night, and the paint was tarnished. The " Pekin," although a 
 fast-sailing ship, had her speed reduced by the fouling to six and a 
 half knots per hour .'" 
 
 The " Oberon," whilst on the Brazilian station, was coated with 
 a mixture of lime and mineral tar, which fouled so badly that in 
 three months it had to be scraped off. 
 
 In November, 1863, the " Recruit," iron-paddle despatch boat, 
 had the hull coated with the patent anti-fouling compo^'s of Messrs. 
 Hay, Wilson, and Crispin, each claiming to possess the secret ; and 
 when taken into dock in August, 1864, the following proved to be 
 the result ; — Hay and Crispin's portions, each very foul, a large 
 number of mussels closely adhering to the iron work, and a consi- 
 derable amount of corrosion.. Wilson's compo' was not so foul, but 
 there was more corrosion than with the others. 
 
 The ' Times ' remarked, that "both compositions (as, indeed, has 
 been the case more or less with every invention of the kind hitherto 
 brought under the notice of the Admiralty) have turned out to be 
 
58 THE FOULING AND CORROSION 
 
 complete failures, as, on the water being pumped out of the dock in 
 which the " Recruit " had been placed, every square inch of the 
 surface of her hull below the water-line was found thickly coated 
 with weeds, sea-grass, barnacles, and various kinds of animalculse." 
 
 In 1865 this same vessel, after having been coated with Hay on 
 one side and Crispin on the other, was found on examination to 
 have Crispin^s covered completely with grass, and Hay's with all 
 kinds of fish, crabs, &c. 
 
 In 1863 the "Recruit" iron paddle-wheel despatch boat had 
 the starboard side coated with Mr. Crispin's anti-fouling composi- 
 tion, and the port side was coated with that of Mr. Hay, the 
 Admiralty chemist. The result, as reported in the ' Times ' of 
 October 17th, 1863, was as follows : — " On the starboard side the 
 entire surface was covered with grass about a foot in length, with 
 which were mixed thousands of sea- worms and barnacles. A minute 
 examination led to the discovery that every portion of the compo- 
 sition had been eaten away from the iron plates, leaving nothing 
 but the coating of red lead applied by the dockyard workmen. On 
 the port side Mr. Hay's composition was found to be still adhering 
 to the iron plates, which were coated over the length of the vessel 
 with a kind of fibrous seaweed from one to three inches in length, 
 and swarming with small shell-fish. In some parts of this portion 
 of the vessel's bottom the weeds were larger and more matted 
 than on the starboard side, while the barnacles here were also very 
 large, the composition being completely penetrated and the iron 
 plating exposed. Altogether, the bottom of the "Recruit," whichhad 
 been only twelve weeks out of dock, was more thickly covered with 
 marine formations than many iron vessels which had been twelve 
 months afloat." 
 
 In February, 1865, Her Majesty's Ship "Valiant" was docked 
 at Portsmouth, and- one side was coated with a " poisoning " anti- 
 fouling compo', of which mercury was the basis, and it was asserted 
 by the inventor that it "not only effectually prevents the least 
 accumulation of animal or vegetable matter, but at the same time 
 preserves the iron from oxidation ;" and the other side had applied 
 to it one of the preparations of copper. In five months after, both 
 sides were found thickly covered with barnacles, weeds, &e. 
 
 At the same time orders were given by the Admiralty for the 
 application of no less than seven coats of Green's " anti-fouling " 
 compo' to the bottom of Her Majesty's Ship " Achilles," the cost 
 being nearly £1 000. In three months after, the ship was docked, 
 and on examination it was found that this expensive operation had 
 been a complete failure, and the mercurial preparation or compo' 
 was nearly as bad. Both these were scraped off, and another 
 "improved" compo', containing copper, was applied to both sides. 
 
 On the 6th April, 1865, the 'Times' announced that the 
 
OF IRON SHIPS. 59 
 
 " Orontes " troop-ship^ and the " Hector " screw iron frigate, had 
 both been docked at Portsmouth, to examine, report upon, and 
 replenish the " preservative " and " anti-fouling •" compositions 
 with which the immersed portions of their hulls had been coated 
 when they were last in dock. The " Orontes " was found to have 
 the bottom free from any important accumulation of weeds, but 
 " under the counter of her stern, and in the run of her lines to her 
 screw aperture, she was thickly encrusted with barnacles, and the 
 bottom was dotted all over with patches of rust, the rivet-heads in 
 many places showing evident signs of being affected by the copper 
 contained in the " anti-fouling composition." Then follow the 
 remarks that," as a ' preservative ' to the ship's bottom, the compo- 
 sition appears to have utterly failed. As an ' anti-fouling ' 
 preparation the result is rather more favorable; but this slight 
 advantage appears to have been more than counterbalanced by the 
 failure in 'protective' qualities to the iron of the ship's bottom. 
 The " Hector," on being examined in dock, was found to be covered 
 with long weeds hanging in tufts and festoons, with a moderate 
 quantity of barnacles and a large deposit of corallines aft." 
 
 The ' Times ' of November 17th, 1863, reported that the " War- 
 rior/' having been taken into dock four months and a half after a 
 former docking, when she was coated below the water-line with a 
 ''preservative" and "anti-fouling" composition, and had at the same 
 time three patches of " vitreous sheathing " attached to her port 
 side, it was found on examination that " the ship's bottom, as she 
 now lies in dock, has the appearance of a well-made thrummed 
 mat, being covered with a fine crop of tuft weed, which must have 
 grown at the rate of about three quarters of an inch per month 
 since the ship has been afloat to reach its present condition. 
 There are existing indications of mischief to the rivet-heads at the 
 bows of this ship to warrant a careful scraping and examination of 
 every part of the ship's bottom from keel to water-line." 
 
 The ' Shipping and Mercantile Gazette ' of September 1st, 1865, 
 records the fact that the " Ceylon " and " Poonah," iron steam- 
 ships of the Peninsular and Oriental Company, were each coated 
 with a " new " compo', and the result wJas " most extraordinary." 
 Both ships have returned after their first voyage of a few weeks in 
 a most shocking plight. The " Ceylon," notwithstanding she had 
 been twice scrubbed abroad in less than two months, was found 
 covered with grass from twelve to eighteen inches long, and 
 barnacles and zoophytes, &c., had began to form all over the 
 bottom, so that she was delayed on her homeward voyage several 
 days beyond her usual time of arrival. The "Poonah" was nearly 
 as bad after only six weeks' absence." 
 
 A great idea seems to have taken hold of some of the inventors 
 of anti-fouling compositions, which is that the mucus of, fishes 
 
60 THE FOULING AND COEROSION 
 
 was the pattern to be kept in view in any attempt to keep iron 
 ships' bottoms free from fouling, and one inventor has stated " that 
 the most valuable and persistent protection for the bottoms of these 
 vessels will be found in the direction of mucus, and not in that of 
 metallic paints." One person has actually proposed to adopt some 
 means to cause a constant film of oil to be kept on the surface of 
 the hull of a ship, so managed as to be perpetually renewed as it 
 comes oflF, and thus keep the. bottom clean. 
 
 Attempts have been made by some inventors of compositions to 
 obtain one which shall act by a constant renewal of the surface, 
 and in this some have succeeded so far as to keep tolerably clean 
 for six or eight months ; but this is very far from what is required. 
 What it is of the utmost importance to obtain, is something which 
 shall keep clean for not less than three years, or the period for 
 which our men-of-war are commissioned ; and this experience has 
 so far shown has not, and cannot be obtained by any composition. 
 
 When anything is used which does not do this for the period 
 named, it must be looked on as a failure, for the most important 
 point to be attained in our large iron-clads is that they should not 
 have to be docked during their commission ; and any plan which does 
 not secure this must be deemed useless. No composition will 
 adhere equally throughout, from the wet or damp state of the 
 plates, the weather, &c., either in being laid on or when laid on ; 
 and as this difficulty cannot be overcome, it is one of the weak 
 points inherent to compositions. One thing is certain, that how- 
 ever well these may answer when experimented with, they fail when 
 applied in practice. 
 
 It is said that our iron-clad ships have to spend fourteen days in 
 dock every six months to have their bottoms cleaned, if, therefore, 
 this be correct, and everything seems to prove its truth, each ship 
 would average one twelfth of her time whilst in commission in 
 being docked solely to have the fouling removed ! and this, too, in 
 spite of the great variety of "successful" (?) " anti- fouling " com- 
 positions which are said to be either in use or else being tested, 
 and of which we so frequently have such flattering reports. 
 
 These compositions, as a rule, would seem to have been origi- 
 nated for the purpose of cultivating and improving marine produc- 
 tions, as they are evidently based on agricultural experience ; for 
 first we have the red lead or the preservative, then the " anti- 
 fouling composition " or the manure, then comes the " top 
 dressing," after which is the harvest, generally resulting in a 
 heavy crop of mixed productions, as objectionable and useless as 
 they are various, and as expensive and troublesome to reap as they 
 are annoying and prejudicial when collected. 
 
 The variety also in the composition of these " manures " is as 
 great as amongst those used by agriculturists, who we hear talk of 
 
OF IRON SHIPS. 61 
 
 guano, phosphate, superphosphate, ammonia, &c., and we find that 
 even guano itself has been proposed to be employed by some of the 
 promoters of the new system of marine agriculture ! 
 
 Experience shows that they do not last, and it is found necessary 
 to have a " bottom cleaning " and " plastering " or " smearing " 
 after each long voyage, besides frequent " hogging ;" in fact, it is 
 admitted that the best of this army of " anti-fouling,^' " anti- 
 corrosive " preparations do not keep a vessel clean for a voyage to 
 India and back, even under the circumstances of the ship being 
 able to leave on her return voyage without having to remain in 
 harbour any time longer than needed to discharge and load ; and 
 their repeated and continued failures, in spite of the highest preten- 
 sions to perfection, have caused it to be remarked that " a com- 
 parison of the results of the great number of expensive compounds 
 now being applied to the bottoms of Her Majesty's ships under the 
 name of ' anti-fouling ' mixtures or compositions, would almost 
 lead to the belief that they tended to encourage rather than dis- 
 courage the growth of marine animalculse or weeds, even in 
 English waters." 
 
 As regards the use of plaster as an anti-fouling, anti-corrosive 
 material, Mr. Lamport well observed at the Institution of Naval 
 Architects in 1864 — " The structure of an iron ship, from her length 
 and material, inust be flexible. Her own weight in a graving dock, 
 independently of the action of the undulations of the waves and of 
 blows from heavy seas, to say nothing of the strains from varying 
 draughts of water and differently disposed cargoes, from touching 
 the ground, or from collisions, will cause sufficient vibration, if not 
 actual working, to loosen, perhaps break up, a brittle coating of 
 cement. If once the adhesion be lost, and moisture impregnated with 
 chemical vitality ooze through a crack in the cement, the remedy will 
 increase the disease by retaining and hiding the mischief of the 
 obnoxious influence." 
 
 According to the experience of Admiral Sir E. Belcher, C.B., 
 corallines were more difficult to be removed from vitreous surfaces, 
 and could not be removed by an ordinary scraper; but wherever 
 they came into contact with copper which is slightly oxidised, they 
 scaled oflf immediately, because they came off with the oxidised 
 portion. 
 
 In 1863 the " Sharpshooter " iron steamship is related to have 
 became so foul with oysters, that when docked at Portsmouth they 
 had to be " dubbed off" with adzes, and came off in flakes of shell 
 of eighteen inches to two feet square, in all cases bringing off a 
 considerable amount of scale from the iron. 
 
 An officer of many years' standing in Her Majesty's service, and 
 who has had very considerable experience in regard to fouling, &c., 
 writes thus respecting the adhesion of barnacles, &c., to ships' 
 
62 THE FOULING AND CORROSION 
 
 bottoms, and the trouble in detaching them: — "Whilst on the coast 
 of Africa, slave catching, in 1850-51, in H. M. S. " Phoenix," we 
 used frequently to hog her bottom, which would become foul in a 
 very short time, and occasionally it was necessary to remove as far 
 as we could the barnacles on the screw (which screw we had not 
 the power of raising), and for this purpose a Krooman went down 
 with an old chisel and scraper. The barnacles stick more firmly 
 than a limpet to a rock/' 
 
 It is stated in the 'Transactions of the Institution of Naval 
 Architects' for 1866, that the " Industry " was coated with an 
 " anti-corrosive, anti-fouling cement," invented by Mr. Szerelmey, 
 with the following results: — "The 'Industry' was undocked at 
 Woolwich on the 5th August, 1858, with Mr. Szerelmey's compo- 
 sition on her starboard side, whilst the port side was payed with 
 ' Peacock's composition ' upon red lead. The vessel was docked 
 again on the 28th May, 1859 (in less than ten months). Upon 
 examination it was found that corrosion existed on both sides in 
 patches, the starboard side the worst, and both sides /om/ with weeds 
 and barnacles." 
 
 Captain Stewart stated that " There is an iron fire-float on the 
 River Medway at Chatham which has had several compositions 
 tried on her bottom. There are also some buoys moored in the 
 Medway on which compositions have been tried, including Portland 
 cement, and I am a witness to the failure of the whole of them." 
 
 Admiral E. P. Halsted, whose indefatigable endeavours in aid 
 of progress, and conscientious, careful, and thorough investigation 
 of any subject he takes in hand, are well known, in his interesting 
 and valuable lectures on "Iron-cased Ships," read before the Royal 
 United Service Institution in 1861, speaks of the " great and rapid 
 fouling of the ships' bottoms, due to the facility for adhesion oflFered 
 to every marine substance by the surface of every material yet 
 applied for the protection of the bottom from corrosion, and this 
 objection, costing its annual tens of thousands among all concerned, 
 remains to the present day. If the speed of the "Warrior" should 
 be reduced from fourteen to twelve knots, which a reference to the 
 cases of the " Himalaya" and other transports of iron will show to 
 be no excessive loss from the rapid and great fouling of the bottoms, 
 then such reduction will, in accordance with well-known laws, be 
 equivalent to a loss of about one third or 400 nominal horse-power 
 in the efficiency of her engines ; and for this loss there will be no 
 compensation in any corresponding reduction of the fuel used, for 
 the whole steam stable will have to do its utmost to obtain even 
 this lower speed, and will demand its food accordingly. Therefore, 
 as compared with efficient work, this lower speed must be obtained 
 at a loss of about £40 a day. Present experience tells us that this 
 loss must be incurred throughout such period as the obstruction 
 
OF IRON SHIPS. 63 
 
 may be allowed to last twice a year ; and, according to present 
 knowledge, the sole remedy against both its duration and increase 
 is in a process of docking, cleaning, drying, painting, varnishing, &c. ; 
 and who is to say how long one of our 6000 ton ships, with a 
 draft of twenty-eight feet; will not have to ' stand knocking ' at 
 dock gates, which they cannot enter until tides permit this remedy 
 to be applied, whilst they must be equally forbid to go to work at 
 sea again until it is applied, under pain of the horses eating their 
 very heads off without avail. The number by which we may pre 
 pare to multiply this annual loss in money, time, efficiency, anci 
 labour, but, above all, in absence from stations when possibly most 
 wanted, ampunt to seven, to be multiplied again in each case by 
 two, so that there is likely to be a very pretty little bill to pay each 
 year for the continued liability of iron bottoms to foul, even if our 
 iron-cased ships should be limited to the number at present built 
 or building. But as I gather that my countrymen intend not to 
 give over our great rival 'permanently' that commercial supe- 
 riority she has contrived so astutely to seize from us at present, the 
 above multiplier is likely before long to be largely augmented, and 
 thus the matter, in whatever light viewed, assumes the proportions 
 of a national question ; and it is alone by regarding it in this im- 
 portant view that it is at all likely, in my opinion, to be successfully 
 solved, for in respect to commercial shipping it has been felt as a 
 weighty question long enough to have been solved many times over 
 before now, if its solution had not been in reality a very stiff job." 
 So thoroughly impressed was the admiral with the desirability of 
 having this serious drawback of iron ships obviated, that he con- 
 tinues — " The question here mooted is one of national interest far 
 above the money cost involved in its solution ; and if only in the 
 bare hope of drawing national attention to it, so as to elicit an 
 expression of public opinion whether a more public mode of solving 
 it may not this time be adopted. I beg to set the ball a going thus : 
 " 1. May the Legislature be indj^ced to vote at once the sum of 
 say jS 10,000, for the discovery of the more effective means 
 of keeping clean the bottoms of ships of iron, to the same 
 extent as copper now keeps clean the ships of wood, com- 
 petent j udges being publicly appointed, the scale and con- 
 ditions of awards being published, and the whole available 
 talent of the country invited to compete. 
 " 2. Let every facility of all public establishments and . all 
 official and relevant information be fully accorded to all 
 competitors whom the judges may acknowledge to be 
 such, all necessary precautions being taken to distinguish 
 between true men and mere pretenders. 
 " 3. No competitor securing an award to be allowed to patent 
 the discovery awarded. 
 
64 THE FOULING AND CORROSION 
 
 " Should a twelvemonth of such effort fail to elicit what is required, 
 even the test afforded by such an effort would be most valuable in 
 its proof that to invest iron itself with the desired property must 
 be left for mere time or for some happy accident to determine ; 
 but in order that the effort be not barren, let the terms of compe- 
 tition equally apply to the substituting for iron of any other metal, 
 simple or compound, but equally as strong and otherwise unobjec- 
 tionable." 
 
 Admiral Halsted remarked at the Institution of Naval Archi- 
 tects, in 1861 — " Now I come to another terrible business, and 
 one in which, I hope, my colleagues in this institution will take 
 an active part. Here is the " Warrior," with her 1350 nominal 
 horse-power engines, to go 14 knots an hour. But, pray, for how 
 long ? How many weeks will elapse at sea before the fouling of 
 her bottom will reduce her 14 knots an hour to 12, or even less 
 than that ? As everybody here knows, perhaps, better than myself, 
 the fouling of ihe bottom of iron ships is a question connected, 
 and closely connected, with the nature of the material itself; but 
 I think it is not generally understood that it is not a mere question 
 of the difficulty of preventing the corrosion of the bottom of iron 
 ships. There are a dozen ways by which actual corrosion of the 
 metal may be prevented, but the misfortune is that all these ap- 
 pliances have the effect of presenting such an enticing surface to 
 marine substances and animals, that they carry on their little ope- 
 rations till there is no end of them, and in six months the surface 
 of the bottom of your ship is destroyed, in a great measure, for all 
 purposes of speed. It is wonderful the money paid away in this 
 country on that account. We possess some 600 iron screw ships, 
 and there is not one of them but is subjected to this difficulty at 
 least twice a year. And it is not the mere expense of hauling into 
 dock, cleaning the bottom, and repainting ; but it is the number 
 of steam horses that have to feed to their fullest extent constantly, 
 although the effect produced by their efforts is gradually diminish- 
 ing. Neither is it that the steam horses cannot take the amount 
 of food ; on the contrary, the tendency is rather to over-feed them 
 at such times, so that the reduced speed has no compensating 
 economy ; but the whole effect is a dead loss. What, then, should 
 prevent the council of such an Institution as this submitting that 
 some definite means should be taken to overcome this disreputable 
 fact, which has exposed us to so much public loss up to the pre- 
 sent day. I attribute our neglect of this point entirely to the fact 
 of the Government condemnation of iron ships hitherto as unfit 
 for the purpose of war. Had it not been for that most unjust and 
 impolitic condemnation, I believe a remedy or a substitute would, 
 as a great national object, have been provided long ago." 
 
 Hitherto attention has been almost exclusively directed to ob- 
 
or IRON SHIPS. 65 
 
 taining some paint, varnish, composition, plaster, or other con- 
 trivance, which, when applied to the coating of vessels' bottoms, 
 shall prevent the destructive agency of the worm, if of wood, and 
 the waste or wear of the copper sheathing ; and when applied to iron 
 vessels, the fouling and corrosion of the plates; but so far it must 
 be said without success, for although some of them may do so 
 tolerably well for six or eight months at a time, still this is far 
 from what ought to be obtained or should be desired. The great 
 aim of all who try in this direction should be to obtain a plan 
 which shall be perfectly successful in both directions for the whole 
 period of a ship's commission — say three to five years — and so do 
 away with the frequent dockings, waste of time, and expense, which 
 are not yet in practice overcome by the best of them. 
 
 Attempts seem to have been made to use oxides or sulphates of 
 some oxidizing or easily oxidisable material, by mixing them up 
 with grease or some other vehicle to keep them together, into a 
 sort of paint or compo, and then smearing or plastering them over 
 the whole under-water portion of the hull of the ship, the avowed 
 intention being that the water and its action shall cause the ma- 
 terial to exfoliate, and thus wear oS and keep the bottom clean. 
 A little consideration of the subject would have shown that a far 
 better, more common-sense, and practical plan would have been to 
 have found a metal that would do all this, attach it to the ship, 
 and have done with it, as by this means far greater durability 
 would have been attained, and less likelihood of the protecting 
 surface being displaced or washed off by the friction of the ship 
 when passing through the water. 
 
 It has been proposed to use oxide of zinc, or metallic zinc in 
 powder, mixed with oil, to paint the bottoms of iron ships, in order 
 to prevent oxidation and fouling ; but it seems to have been for- 
 gotten that oil acts as a non-conductor, and will prevent the very 
 galvanic action which is so necessary in order to obtain the ad- 
 vantages which zinc cannot fail to give when applied to iron. 
 
 Increased zoological and chemical knowledge cannot fail to show 
 that " poisoning" is an absurdity, and that success is most surely 
 and certainly obtained by applying the zinc in its metallic state in 
 the form of metal sheets to the hulls of iron ships. 
 
 Of course, because this has not been done before, there are not 
 wanting those who express their firm conviction that it cannot 
 succeed, and will not act in the manner described, especially as 
 when applied to wooden hulls it is not so good as copper or yellow 
 metal; but a very moderate amount of chemical knowledge shows 
 that its application in a successful manner is a mechanical ques- 
 tion, and this once overcome, there need be no anxiety as to its 
 satisfactory operation. 
 
 Glazing, painting, plastering, poisoning, pickling, and all sorts 
 
 5 
 
66 THE FOULING AND CORROSION 
 
 of schemes, possible or impossible, seem to have made no difiFer- 
 ence, have engaged the attention of various persons, though but 
 few would appear to have studied the subject so as to thoroughly 
 comprehend the principles and action necessary to be obtained in 
 order to secure success. Due consideration of the subject would 
 have shown that a permanent surface presents a favorable condition 
 for the growth of barnacles, zoophytes, weed, &c., and that although 
 poisoning them might be good in theory, it would be inadmissible 
 in practice, first, because it would be found extremely difficult to 
 ensure its adherence to the iron hull ; and next, if it did adhere at 
 first, its duration in an active state over the whole surface might 
 be taken as highly problematical, and its easy removal, if merely 
 smeared on, could not fail to be a serious objection. And, above 
 all these, comes the greatest objection of the whole, which is, that 
 from none of the barnacles, polypi, &c., holding on by their mouths, 
 it is pretty evident that the effect of the" poisoning process, so far 
 as these gentry are concerned, must be set down as nil. 
 
 Amongst the many materials for preventing fouling and corrosion 
 of iron ships which have had patents taken for their use or been 
 experimented with, will be found silicates, quicksilver, plumbago, 
 gutta percha, asphalte, shellac, guano, cowdung; now comes a 
 powerful compound consisting of " clay, fat, sawdust, hair, glue, oil, 
 logwood, soot, &c., mixed,'' to be plastered on the ship's bottom; 
 then we have " emery, shellac, and castor-oil ;" next " pitch, tar, 
 and shellac;" next comes another peculiar compound, "baryta, 
 litharge, arsenious acid, asphaltum, oxide calcium, and creosote ;" 
 then another, " Burgundy red earth, grease, lime, unburnt earthen- 
 ware, chalk or Eoman cement." Next follows a very curious com- 
 position consisting of "grease from boiled bones, kitchen stuff 
 and butter without salt, mixed with poisonous matters ;" now we 
 have the grand chef-d'oeuvre of the whole, which is thus described, 
 " Sugar, muriate of zinc, wax, soap, calcareous stones, phosphate of 
 soda, sulphate of zinc and copper, and the syrup of potatoes or 
 sugar wdth powdered marble, quartz, or felspar." The last one 
 ■which will be 'noticed consists of " asafoetida with pitch, tar, resin, 
 and turpentine smeared over the bottom, and then coated with 
 paper or cloth." Who will say after all this, that poisoning and 
 physicking have not had a fair chance ? 
 
 It is admitted that even with the most successful of the " anti- 
 fouling " and anti-corrosive " paints or compositions, which are now 
 before the public, the vessel ought to have a docking and " top- 
 dressing " at the end of six months, though it is said that some have 
 gone so long as nine months without being " top-dressed." 
 
 In January, 1848, the iron steamer " Megsera " had the " anti- 
 fouling " compositions of eight makers applied to different parts of 
 her hull, and on examination after running the usual time, the 
 following results were reported by her captain : 
 
OF IRON SHIPS. 67 
 
 1. iee's composition. — As foul as red leadj hard when scraped, 
 but there was corrosion in spots. 
 
 2. Moresby's composition (aloes and red lead). — Could not be 
 distinguished in any way, either in colour or cleanliness, from red 
 lead. 
 
 3. Clark's composition.— "No. 1. Foul, rusty appearance outside, 
 and corrosion penetrating into the plates. No. 2. Very foul, and 
 much corroded. 
 
 4. Ince and North's composition. — Barnacles and grass as on red 
 lead, but no corrosion, and when scraped the composition appeared 
 perfect. 
 
 5. Hay's composition. — Much corroded and foul. 
 
 6. Chanter's or Weddersted's. — No. 1. Foul and much corroded. 
 No. 2. Appearance clean and without corrosion, excepting upon 
 after part of plate ; but when struck with a hammer it scaled off, 
 showing that corrosion had taken place beneath the paint. 
 
 7. Grantham's composition (one part tallow, two resin, one sul- 
 phur) . — Foul, and very much corroded. 
 
 8. Parker's composition. — More corrosion, barnacles, and grass, 
 than upon red lead. 
 
 The ' Times ' of September 23rd, 1864, stated that the " Achilles" 
 about January, 1864, was payed with " Hay^s compound," and after- 
 wards lay in Chatham harbour for nine months ; at the expiration 
 of which time she was examined and found to be covered with 
 weed and barnacles, some of the former measuring two feet in 
 length." 
 
 On the 6th of October, 1864, the ' Times ' remarked, " It should, 
 however, be taken into consideration by those who are keenly 
 watching the approaching performance of the " Achilles," that as 
 much probably as two knots per hour must be allowed in her rate of 
 speed, in consequence of the foul state of her bottom." 
 
 The 'Times' of Nov. 23rd, 1864, contained the following par- 
 ticulars relating to the floating fire-engine in Chatham Harbour : 
 — " On being hauled up on the slip the condition of the bottom of 
 the vessel afforded another proof of the worthlessness of all the so- 
 called ' anti-fouling ' compositions hitherto in use in the Royal 
 Navy for preserving the iron plating, and at the same time pre- 
 venting the accumulation of animal and vegetable matter on the 
 bottoms of iron ships. Only a few months ago the submarine 
 portion of the floating fire-engine was carefully payed over with 
 the most approved of the many mixtures hitherto brought under 
 the notice of the Admiralty; but so far from the composition 
 having the desired effect, the bottom when examined was found 
 completely covered with a field of grass and seaweed, the latter 
 from four inches to upwards of a foot in length ; while there was 
 an unusually large accumulation of barnacles and other mollusca. 
 
68 THE FOULING AND CORROSION 
 
 the greater portion of the composition being eaten away, leaving 
 the iron plates completely exposed." 
 
 That the repulsion of barnacles and seaweed and the mainte- 
 nance of the ship's bottom in a clean state may be accomplished, 
 it is necessary that the surface of the metal employed should ex- 
 foliate, and where this action is obtained the barnacles, mussels, 
 and other fouling matter have no sooner obtained a hold than they 
 are at once detached, together with the surface on which they have 
 " squatted " or attached themselves, the process being an " action 
 of ejectment," but of a far more certain, suinmary, and rapid 
 character than the legal operation known by the name. 
 
 The common belief has been that copper and yellow metal 
 sheathing kept clean and free from fouling from their poisoning 
 the barnacles, weeds, &c., by the verdigris which the water caused 
 to form on the surface; and when in 1765 H.M.S. "Alarm," the 
 first vessel that was coppered in the Royal Navy, was found to 
 have her copper bottom perfectly clean after a four years' trial, 
 the success was attributed entirely to its poisonous character. 
 
 Sir John Hay said, at the Institution of Naval Architects in 
 1866, that " there was a sort of belief that one of the advantages 
 of copper consisted in the fact that the verdigris destroyed the 
 marine animal or vegetable substance which attaches itself to the 
 ship's bottom, and so causes fouling ; but the fact is, that the 
 action of copper in keeping a ship clean is mechanical. We find 
 that copper oxidises in parallel layers, and that it sheds ofi' in very 
 thin layers, so that the substances which cause the fouling of the 
 ship attach themselves to the copper, and having attached them- 
 selves to the copper they lose their hold, and are detached by the 
 continual exfoliation of the copper." 
 
 Admiral Sir Edward Belcher, C.B., remarked, respecting the 
 necessity of the galvanic action, " As to the adhesion of moUusca 
 to ships' copper bottoms, where there is no such action going on, 
 and where the vessel is not rapidly fprced through the water, the 
 case of the ' Ardent ' at Bermuda furnished the finest specimens ; 
 and most magnificent specimens of different shell- fish, spondyh, 
 were afterwards sold, some as high as ten guineas each." 
 
 It has been remarked somewhat dogmatically, that "for pro- 
 tecting iron vessels against corrosion and the adhesion of barnacles, 
 the use of a poisonous paint is in all cases indispensable, and this 
 paint must be slightly soluble in water, else the poison in it will 
 be of no avail." 
 
 Mr. John Bourne, in the ' Artizan ' of 1844, considered " marine 
 glue " preferable to paint for coating the bottoms of iron ships, 
 and " by mixing this substance with arsenic previous to its appli- 
 cation, the adhesion of weeds and barnacles will be effectually pre- 
 vented. In fact, an arsenical paint of any kind is an effectual 
 
OF IRON SHIPS. 69 
 
 remedy against these adhesions, the arsenic being destructive of 
 both animal and vegetable life," 
 
 Experience, however, has proved most satisfactorily the fallacy 
 of this statement, and daily increasing proofs are given of its utter 
 inutility, even when tried under the most favorable circumstances 
 and conditions, for producing this " indispensable " effect ; whilst 
 at the same time satisfactory proof is given of how completely the 
 action of metallic sheathing in keeping clean is misunderstood 
 even by those who have professed to be the greatest authorities on 
 the subject. 
 
 Professor Wilson is said to have proved in a very satisfactory 
 manner the utter inutility of the " poisoning " process, and this 
 not by theory but practice. In order to obtain the true result, 
 whether for or against, he took the most subtle-known poisons 
 and mixed them with ordinary paint, and smeared some wood and 
 iron with them. Barnacles soon grew to a large size on these 
 paints, and he then took some of them off, boiled them, and gave 
 them to several animals, which were poisoned by the mess. This 
 would seem to show that such nuisances are very tenacious of life, 
 and able to thrive on what proves to be the destruction of less 
 
 Fig. 1. 
 
 tougher and useless animals, giving at the same time a rather 
 severe blow to the " poisoning " theory. 
 
 The author has often tried to eat the oysters which are dredged 
 up on the Cornish coast, and are well known from their beautiful 
 green colour ; but he has invariably found them to be so strongly 
 impregnated with copper, to which their colour is owing, as to be 
 positively uneatable. He has also in his possession a photograph 
 from a large bunch of barnacles (of which Fig. 1 is an exact copy, 
 
70 THE FOULING AND CORROSION 
 
 full size), which were taken off the brass screw propeller of 
 H.M.S. "Phoenix'' whilst stationed on the coast of Africa, where 
 they had flourished well and grown to a large size, in spite of the 
 "poisonous" character of the substance to which they had 
 attached themselves. It is well known that in. the heated water 
 of the tropics the corrosion or oxidation of any metal proceeds 
 with greater rapidity than in the cooler waters of the temperate 
 zone ; therefore it is but fair to assume that the brass screw would 
 have been covered with a sufficient amount of verdigris to have 
 given the poisonous properties a fair chance of acting. 
 
 Mr. Mallet, who, amongst other things, had tried his hand at 
 anti-fouling compositions, says of them : — " They are at best but 
 mere palliatives, for it is a fact that they all do foul after a time 
 longer or shorter, over the whole surface. The stuff gets stripped 
 off by the washing of the water or accidentally, and as soon as 
 that takes place the remaining portion begins to get coated with a 
 thin film of carbonate of lime deposited from the lime in the sea- 
 water; and the moment that deposit takes place the surface 
 becomes a fit nidus for the lower marine animals and vegetables, 
 and then fouling goes on. We therefore come to this conclusion — 
 that some better method is wanted for the protection of iron ships 
 than is afforded by any chemico-mechanical method of coating yet 
 proposed." 
 
 It is the rule in many cases that ships coming from a foreign 
 station, and which have been at sea sufiiciently long to get 
 tolerably foul, are frequently "hogged" before arrival, and are 
 docked during the night, and gangs of men are put on to scrub 
 down the under-water portions as the water recedes, so that the 
 weed, &c., may be carried out by the rush of water from the dock. 
 In the morning the ship is examined, and found to be " exceed- 
 ingly clean and free from fouling," or else " had not a bit of weed 
 an inch in length on her bottom," nor more than " one solitary 
 barnacle." Such facts can be easily ascertained by any one who 
 will take the trouble, but are not the less true because they may 
 be classed amongst " things not generally known." 
 
 The ' Times ' of the 18th of November, 1864, says :— " Not- 
 withstanding the numerous descriptions of what are termed anti- 
 fouling compositions which have been submitted to the Admiralty, 
 no discovery appears yet to have been made of a preparation for 
 effectually preventing the accumulation of animal and vegetable 
 matter over the hulls of iron vessels. Although the bottom of the 
 iron frigate " Achilles " was coated over with the anti-fouling com- 
 position of Mr. Hay, the Admiralty chemist, before her launch, so 
 foul had the bottom of that vessel become while in Chatham har- 
 bour, preparing for sea, that in the run from Chatham to Devon- 
 port her speed fell off more than three knots an hour from her 
 
01' IRON SHIPS. 71 
 
 steaming rate on the occasion of her official trip to the Maplin 
 Sands." 
 
 In regard to the latest experience of " anti-fouling " and " anti - 
 corrosive " paints, compositions, &c., the result of eighteen months' 
 trial of some of the best of them as tried on H.M.S. " Valiantj" 
 is thus given in the ' Standard ' of January 10th, 1867. 
 
 "The 'Valiant,' armour-plated ship, 24 guns, 4063 tons^ SOOhorse- 
 power, for some time placed in the steam reserve, was yesterday- 
 hauled into dock at Portsmouth, after having heen made for the past 
 eighteen months the object of experimental trials of various kinds of 
 anti-fouling paints. The state of her hull when thus exposed was such 
 as to convince any unbiassed person of the complete inefficiency of 
 all anti-fouling nostrums, and to- prove the absolute necessity for 
 sheathing iron ships with a metallic covering of zinc in the same 
 way as wooden ships are sheathed with copper. In August, 1865, 
 she was painted below her water-line on the whole of the starboard 
 side with Gisborne's mercurial varnish ; on the larboard side the 
 bow quarter with Mr. Hay's composition, a washing of oxide of 
 copper, we were told, over a coating of marine glue; the stern 
 quarter with that of Mr. Rowett ; and a small portion of the mid- 
 ship section with a sort of enamel by Mr. Jennings. Mr. Gis- 
 borne's process is to first coat the iron skin of the ship thickly with 
 red lead and then to wash over with another kind- of red paint, the 
 main base of which is crude mercury. The action relied on, there- 
 fore, seems to be in some sort galvanic, but of so weak a character 
 that it is impossible it can be compared with the more energetic 
 and safe action of an absolute covering of zinc sheathing as has 
 been proposed and successfully experimented upon by Mr. Daft, 
 C.E. Even the slight voltaic action of the mercury would seem to 
 have been sufficient to prevent a high degree of fouling, for Mr. Gis- 
 borne's portion of the hull showed a cleaner surface than any other, 
 although this was far from smooth, and was sprinkled about with 
 considerable fields of short fine weeds, with here and there clusters 
 of shrubby algals, interspersed with considerable colonies of living 
 mussels. Where the anchor had chafed against the skin of the ship 
 and at other similarly bared spots the corrosion of the iron was very 
 manifest. Mr. Hay's portion was the next cleanest in appearance 
 to the eye, but the surface of this part of the ship seemed all 
 streaked about as if it had been ' hogged.' It must not be thought, 
 however, that this part of the hull was by any means clean. At 
 regular intervals of about twelve or fifteen feet apart were large 
 bunches of the long ribbon-like lamin arise, the cause of which was 
 assigned by the workmen in the dockyard to the shoring of the 
 vessel in the dock previous to her long mooring in Portsmouth 
 harbour, these patches of seaweeds being on the sites where the 
 ends of the shores had rested, and at which some chafing of the 
 
72 THE FOULING AND CORROSION 
 
 composition had possibly taken place. How the iron plates be- 
 neath this composition have stood the trial no one, we suppose, yet 
 knows; but the extreme danger of applying copper in any form or 
 connection is too well known not to make it a matter of surprise 
 that the Government should permit the trial of any compound of 
 that metal upon the hull of so large and so costly a ship. Of the 
 state of Mr. Jennings's enamel it was difficult to judge, the por- 
 tion covered with it being small and lying low down under the 
 ship's bottom. The water had not been suflSciently emptied out 
 of the dock when we left the dockyard to enable us to judge with 
 certainty. So far as could be seen it looked as if thickly coated 
 with slimy matter. But the quarter assigned to Mr. Kowett was 
 in a state of the most luxuriant growth ; thousands of olive tangles 
 hanging down for a length of six or seven feet, and all the general 
 surface of the hull being a dense mass of animal and vegetable 
 parasites. We have rarely seen anything so bad." 
 
 The following from the 'Times,' January 11th, 1867, gives their 
 statement of the results of these trials : — " The ' Valiant,' iron-clad 
 frigate, in dock at Portsmouth, was yesterday surveyed by the offi- 
 cials of the yard, to enable them to prepare the requisite official 
 reports on the state of the several experimental compositions with 
 which her hull below the- water-line has been coated, to preserve 
 the iron of the ship's bottom, and to prevent fouling. The primary 
 requisite qualifications for all paints or patented compositions paid 
 over the bottoms of iron ships is necessarily the 'preservation' of 
 the iron. The secondary and much less important consideration 
 is the efficient action of the paint as an anti-fouler. The ' Valiant' 
 was docked at Portsmouth on the 9th of August, 1865, and re- 
 mained in dock until the 11th of September, thus giving ample 
 time to the various compositions which had in the meantime been 
 paid over her bottom to become thoroughly dried, before she was 
 again placed in the water. The entire starboard side of the ship 
 was coated with Gisborne's anti-fouling mercurial composition, laid 
 on in four coats upon red lead. The port bow to nearly amidships 
 was paid over with the 'Hay' anti-fouling composition, laid on 
 upon a coating of the ' Hay' preservative varnish. Amidships, 
 from the keel upwards, was a patch of Jenkins's enamel, and the 
 remainder of the vessel below the water-line aft was coated with 
 Rowett's anti-fouling paint, both the Jenkins and Rowett being 
 laid upon the Hay preservative varnish. The vessel having been 
 afloat, but in still water, at harbour moorings, for sixteen months, 
 afforded a very fair opportunity for judging the relative merits of 
 the various competitive compositions ; but this cannot be completed 
 before the bottom of the vessel has Ijeen scrubbed, and the exact 
 effects of the damage from the anti-fouling mixtures upon the iron 
 of the ship's bottom, if there be any, has been fully ascertained. 
 
OF IRON SHIPS. 73 
 
 At present the Rowett patch of composition is closely covered with 
 an average depth of six inches of polypi and sea-grass near the 
 water-line of as many feet in length. The Jenkins patch was nearly 
 as bad, and both give strong evidence of corrosion, the real nature 
 and extent of which will only be ascertained when the ship^s bottom 
 has been scrubbed. The Gisborne composition has kept the star- 
 board side of the ship moderately clean, but the red-lead under- 
 coating is decomposed, and the rivet-heads give evident signs of 
 corrosion. Electric currents have been at their dangerous work, 
 but this Mr. Gisborne ascribes to the fact of red lead having been 
 applied to the bottom of the ship by Admiralty order, instead of 
 the peculiar varnish recommended for the purpose by Mr. Gis- 
 borne. Mercurial paints may possibly be perfect as anti-foulers, 
 if laid on a proper underlying protectral varnish, such as is used 
 by the Admiralty chemist, but mercurial paints laid on red lead 
 might also possibly destroy the bottoms of the iron ships of Her 
 Majesty's navy. The Hay composition on the ship's port bow only 
 remains to be noticed, and this can be done very shortly. The 
 fouling is very slight, although a trifle in excess of that on the 
 Gisborne paint. The composition appears perfectly sound in every 
 part, and there is no corrosion excepting where abrasion has taken 
 place from the chain-cables or from the dock shores. As, however, 
 we have already observed, the ship's bottom must be thoroughly 
 cleaned of the polypi, sea-grass, and other adhesive substances, 
 before any correct estimate can be formed of the peculiar qualities, 
 favorable or otherwise, of the respective compositions. Connected 
 with this docking of the ' Valiant' has been the trial of a patent 
 scraper and revolving brush, the invention of Mr. Harrison, of 
 Liverpool, for scraping and cleaning the bottoms of iron ships at 
 times when it may be advisable to save the expense and delay of 
 docking, or when docks may not be available. The scraper and 
 the brush were both passed over two strips of the ' Valiant's ' star- 
 board side previous to her being placed in dock, the operation 
 being exceedingly simple, and the action of the scraper or brush 
 on the ship's bottom certain. On examining the 'Valiant's' bottom 
 in dock yesterday, those parts over which the scraper or the brush 
 had been passed were perfectly clean, and the results of the trial 
 of the small machine — for it is small in consideration of the work, 
 it does — was thus far most satisfactory." 
 
 It has been said that the requirements of a shipowner or mer- 
 chant in a vessel should consist of the following points : 
 
 1. Strength combined with lightness. 
 
 2. Great stowage capacity. 
 
 3. Safety. 
 
 4. Speed. 
 
 5. Durability. 
 
74 THE FOULING AND CORROSION 
 
 6. Economy in maintenance and repairs. 
 
 7. Cost of ship. 
 
 8. Draft of water. 
 
 Now, assuming that the ship has been constructed in iron, to 
 obtain all of these in the fullest manner, at the commencement, 
 experience has shown that unless special attention has been di- 
 rected to the overcoming of the two serious evils of fouling and 
 corrosion, and special means taken to render their prevention cer- 
 tain, that either of them are sufficient to speedily do away with 
 the beneficial results which had been otherwise obtained; but there 
 is also this important and serious drawback if these points have 
 been neglected, which is, that both corrosion and fouling invariably 
 accompany each other, and combine to render the destruction of 
 the ship a comparatively speedy operation. 
 
 In the report of the Committee on Dockyards and Basin Ac- 
 commodation it is remarked, that on foreign stations the provision 
 of dock accommodation has become almost indispensable in conse- 
 quence of the conversion of the navy into a steam navy. In 
 former times it was the practice to heave ships down in careening 
 wharves when in want of repair ; but this expedient is not resorted 
 to in the case of steam vessels, as their machinery would be de- 
 ranged by the operation; and consequently, on stations where 
 there are no docks of sufiScient size, it is necessary to send them 
 home whenever their bottoms require to be either cleaned or re- 
 paired. During their absence from their stations the cost of wages, 
 victuals, coals, and of wear and tear, is a dead loss, and this loss 
 would be of constant recurrence in the case of iron ships, as it is 
 necessary to dock them for the mere purpose of cleansing their 
 bottoms at least four or five times in the course of the ordinary 
 duration of a commission. 
 
 On this it has been remarked that " the proposal to build docks 
 on all our distant stations for our men-of-war to be cleaned in does 
 not meet the question, for the intention of sending a vessel from 
 this country is hardly for the purpose of putting her into dock for 
 a fortnight immediately on her arrival at her cruising ground. The 
 building of docks is, besides, only half the afiair ; being built, they 
 require fortifications, and a strong force to prevent their being de- 
 stroyed, the existence of a dock alone making the destruction of it 
 an important blow as long as vessels are dependent on it for re- 
 maining eflBcient. They must be defended by regular fortifications, 
 for the experience of what has taken place in America (if it were 
 required) shows us how detached, irregular works can be passed 
 by iron-clads, and a ship or even a boat's crew of the enemy might 
 surprise a vessel helpless in dock, and destroy her, and an enemy's 
 squadron, should . the place not be sufiiciently strong, gives the 
 alternative of the destruction of the town, or of the docking and 
 
OF ikoN SHIPS. 7o 
 
 coaling of our own ships. The docks may do very well for peace, 
 when it is not really of so much consequence whether a cruiser is 
 a knot or more faster, but, excepting at enormous cost, they will 
 not meet the requirements of war." 
 
 The " Megsera," when taken into dock after eight months from 
 the former docking, was found, in the words of her captain, in an 
 extremely foul state, in fact, like a mussel bed ; and in three days 
 after the smell from the decayed iish was almost unbearable. 
 Prior to going into dock her steerage was very much affected, and 
 her speed had fallen off from two and a half to three knots, with 
 a strong gale, three reefs in topsail and reefed foresail, scudding 
 with the screw up, she only averaged seven and a half knots, when, 
 if her bottom had not been foul, she would have done ten and a 
 half or eleven. 
 
 This ship burns, at full speed, forty-five tons, of coal per day, and 
 at an average speed of ten knots she should do with the above 
 quantity 240 miles ; but as it is shown that her speed was dimi- 
 nished three knots per hour, that quantity would only take her 168 
 milBs. Taking coal at £2 per ton on board, her cost for coal alone 
 is j690 per day, whilst the cost of the coal wasted by the bottom being 
 foul amounts to j623 per day; whilst during the time of war, 
 when the price of coal would be much higher, and other things as 
 well, the loss would be correspondingly heavy. 
 
 It has been found, from accurately testing the steamers of the 
 City of Dublin Steam Packet Company, which carry the mails 
 from Holyhead to Kingstown, that during the summer, in about 
 two months after leaving the graving dock, their speed uniformly 
 falls off so as to increase the length of the passage ten to fifteen 
 minutes, or about half a mile to one mile per hour. 
 
 The importance of maintaining an undiminished rate of speed, 
 both under steam and under canvas, but especially under steam, 
 will be seen when it is remembered that the iron-clads "Resistance" 
 only carries four days' coal at full speed, the " Valiant " three and 
 one third days' coal, and the " Warrior" five days' coal. 
 
 It is and must be a humiliating reflection to us all, that after an 
 expenditure, to say nothing worse, of just seventy millions sterling 
 by the late naval administration, that we have no iron fleet, no 
 guns ; and that those iron vessels which we have, and on which so 
 many millions have been spent, are useless after six months' duty 
 afloat, on account of the fouling of the hulls and the rapid dete- 
 rioration of their speed. What they might be fit for after six 
 months in the tropics may be readily imagined from what has 
 occurred in our own harbours. 
 
 The enormous evils of fouling and corrosion still exist in all 
 these ships in full force ; and both are not a little increased by ill- 
 judged attempts at prevention, the most glaring of which is that of 
 
76 THE FOULING AND CORROSION 
 
 a wood sheathing covered with copper, the serious damage caused 
 by -which has been amply and, unfortunately, too frequently, 
 proved in our iron-clads. 
 
 In 1864 the late secretary of the Admiralty, when bringing for- 
 ward the naval estimates, spoke in the strongest terms of the diffi- 
 culties caused by the fouling of iron, ships ; but it does not seem 
 to have occurred to any of them, although deeply impressed with 
 the evil, to offer a premium, reward, or other tangible encourage- 
 ment for a practical and efficient remedy, nor to profit by the well- 
 proved principles of chemistry in regard to the proper materials to 
 be employed for overcoming the difficulty. 
 
 The French Admiral Paris, so well known from his scientific 
 investigations and his dictionary of technical terms, says, "When 
 one thinks of the number of steamers on the seas, of the thousands 
 of tons of coals they burn, one cannot help seeing that the wealth 
 of the whole country is being spent in this obstacle, the overcoming 
 of which would produce enormous profits. In the time of war it 
 will often be heard that one vessel has been captured because six 
 months had elapsed since she had been painted, while the victor 
 had perhaps left the dock only three months previous." 
 
 There cannot be the slightest doubt that the result of building 
 iron-clads with iron hulls, which are not and cannot be sheathed 
 in a proper manner, so as to keep clean without damaging the iron, 
 will render it perfectly impossible in war time to employ such 
 vessels on distant stations and for long voyages, or even to use 
 them at all on stations where similar vessels, but provided with 
 properly sheathed hulls, are kept by other countries who at that 
 time may be our enemies. 
 
 The Right Hon. Sir John Pakington, Bart, M.P., President of 
 the Institution of Naval Architects, and First Lord of the 
 Admiralty, remarked at the session of 1866, when referring to the 
 fouling of iron ships and Mr. Reed's remarks on their not being 
 sheathed, " It is a fact which he has just admitted, and which we 
 must all learn with very great regret, that at this moment all those 
 splendid and costly armour-covered ships which have been built 
 for the navy during the last few years are still under the great 
 disadvantage of having no copper over their bottoms." 
 
 Mechanical means for clearing off the fouling whilst the ship is 
 afloat, can only be very partial in their action ; but however effec- 
 tiially they may do their work, they introduce a very dangerous and 
 serious evil, one the importance of which cannot be overlooked, and 
 that is, the removal of the paint, coating, or anti-fouling composi- 
 tion applied to the under-water portion, as must infallibly happen 
 to some portion of the hull, by which the bare iron is at once ex- 
 posed to the action of the sea-water, and the corrosion caused 
 thereby ; and also to the increased liability of fouling which bare 
 
OF IRON SHIPS. 11 
 
 iron always possesses, and this must remain until the ship can be 
 docked, no material being in use which can be applied under water. 
 
 It is stated in one of the plans or systems promulgated for clean- 
 ing the bottoms of ships when afloat, that where the ordinary 
 brushes will not remove the fouling, brushes of wire are to be em- 
 ployed, and the action of these upon the paint or other coating can 
 hardly be doubted, and that its speedy removal by such an opera- 
 tion would be readily accomplished ; this may be called getting rid 
 oi fouling to promote corrosion. 
 
 It has been well remarked that the "remedy would become 
 worse than the disease," as not only would the fouling be removed, 
 but the paint or other, protecting material also, and the surface of 
 the iron hull, be left exposed to the corrosive or oxidating action of 
 the salt-water. 
 
 An American newspaper extracts from the 'Baltimore American* 
 some account of the operation of cleaning the bottoms of the 
 monitors, written by its correspondent at Port Royal. He says 
 that the chief diver. Waters by name, is so used to this work, that 
 he has become almost amphibious, remaining for five or six hours 
 at a time under water. The work is very arduous. The diver sits 
 upon a spar lashed athwart the bottom of the vessel, so arranged as 
 to be moved as the work progresses, and, with a scraper fixed to a 
 long handle, works on both sides of himself as far as he can reach. 
 The mass of oysters that become attached to the iron hulls of one of 
 the monitors even during one summer here is immense. By actual 
 measurement it was estimated that 250 bushels of oysters, shells, 
 and sea-grass were taken from the bottom of the "Montauk'^ 
 alone ! 
 
 Mr. Grantham, in his book on 'Iron as a Material for Ship- 
 building,'' gives a sketch and description of his mechanical scraper 
 for cleaning the bottoms of iron ships, which possibly might act in 
 the case of flush or carvel-built ships ; but he omits to explain or 
 describe how it is to be used in vessels built on the " in-and-out " 
 strake system, and shows it as applied to the bottom of a "carvel'^- 
 built one. 
 
 The ' Mechanic's Magazine,' in the first volume for 1862, con- 
 tains the following remarks : 
 
 " The question of the fouling of iron ships has not attracted the 
 attention of the Admiralty and of scientific men as it deserves; and 
 if some remedy be not found for the evil, it becomes questionable 
 whether iron ships are improvements on wooden ones. 
 
 " We find that the bottom of the ' Resistance,' when placed in 
 dock at Portsmouth on Tuesday last, was in an extraordinary con- 
 dition, in fact, it was foul as if the vessel had gone on a long com- 
 mission, instead of being on the home station. 
 
 " The entire bottom was coated with weeds and grass ; patches of 
 
78 THE FOULING AND CORROSION 
 
 mussels were on the port side, together with a good sprinkling of 
 barnacles. 
 
 " On the starboard side the barnacles extended from stem to 
 stern, with weeds and grass in some places three feet in length. 
 
 " The mussels extended fore and aft, with barnacles as large as 
 a child's head. 
 
 " It is, in fact, surprising how such foulness could have accumu- 
 lated in so short a space of time. It was not because precautionary 
 measures had not been taken. The ship's bottom was originally 
 coated on each side with various protective compositions. On one 
 side the composition was entirely destroyed, and patches of rust, 
 more particularly under the quarter, had eaten their way through." 
 
 Mr. Leo Daft makes the following remarks on preventing the 
 fouling and corrosion of iron ships : — " To ensure a huU from 
 fouling it is absolutely necessary that it should be composed of, 
 or sheathed with, a metal that -will by galvanic action peel or 
 FLAKE off as zinc, copper, or yellow metal. Paints and compositions 
 are utterly worthless in this respect. Enamels, glass, and vitreous 
 substances are equally and utterly useless for keeping a clean hull 
 at sea. Barnacles, crustaceous animals, and weeds will fasten with 
 avidity upon wow-oxidizable material, and hold with such firmness 
 that they can only be removed by the chisel and hammer, or by 
 immersion in fresh water. Abundant proofs of this exist in every 
 direction around us. The smoother and more even a vitrified or 
 similar surface is, the greater is the certainty of its fouling and its 
 difficulty of removal, whilst the foul state of bottles after immer- 
 sion in the sea show how much resistance to fouling they offer." 
 
 " An iron ship should be sheathed with zinc because it is the 
 only metal that stands in a distinctly positive relation to iron, and 
 is, therefore, the only metal which cannot injure iron by galvanic 
 action. Long experience has proved zinc to be an excellent sheath- 
 ing on wood, but its great durability and sluggish exfoliation have 
 been known, under trying circumstances, to allow of a slight accu- 
 mulation of weeds, &c., which is entirely overcome by metallic 
 contact with the iron ; for by that contact slight galvanic action is 
 established, protecting the iron, but increasing the exfoliation of 
 the zinc sufficiently to render the accumulation of animal or vege- 
 table life, however small, impossible ; while the action is not so 
 vigorous as to make any serious difference in its durability. There- 
 fore sheath an iron vessel with zinc, and you have a chemically- 
 protected hull, and a perfectly clean surface at much less cost than 
 copper or yellow metal, with no risk of corrosion of hull from 
 galvanic action, and with equal durability." 
 
 The ' Times ' of July 3, 1865, speaking of the " Great Eastern," 
 contained the following : — "The foul state of the "Great Eastern's " 
 bottom, coated with a six months' growth, at least, of mussels, will 
 
OF IRON SHIPS. 79 
 
 greatly impede lier steerage way, as they certainly will not drop off 
 before she reaches Dover." 
 
 The ' Times ' of January 28th, 1867, relates of the " Great 
 Eastern " that " four years back she was coated," and that when 
 examined on the gridiron a few days before the date of the remark, 
 was found " completely free from barnacles or weeds ;" but admits 
 that " some small mussels were found adhering to her bottom, but 
 these are easily detached; and the ship everywhere presents a 
 most satisfactory appearance." It states that one portion " is now 
 found to bo covered with soft rust more than half an inch (!) in 
 thickness ;" but this part of the vessel, of course, was not coated 
 with any composition. 
 
 Winter, being a period when the growth of weeds, barnacles, 
 and other fouling annoyances is generally torpid, or at least very 
 inactive, cannot be taken as a pi;oper period of the year in which 
 to try the eflSciency of any anti-fouling preparation. This can only 
 be properly done during the spring and summer months, when 
 vegetation commences, increases, and is maintained with great 
 vigour ; and as at this season the increased temperature of the 
 water is most favorable to the development of these annoyances, 
 this must be looked on as the proper course to be followed. 
 Trying prevention where no cause exists, cannot for a moment be 
 either sensible or useful. 
 
 The 'Engineer' of June 23nd, :1866, ; contains the following 
 remarks on desiderata in iron ships : — "In the midst of the sort of 
 vain satisfaction with which the application of iron in large quanti- 
 ties to shipbuilding is mostly regarded, it is often forgotten that at 
 least two most important problems in iron ship navigation yet wait 
 for a generally accepted solution. The first of these is the preven- 
 tion of the local attraction of the hull on the compass ; the second 
 would consist in some mode of keeping the metallic bottoms sound 
 and free from the submarine organic growths which so materially 
 affect the speed of the vessel." 
 
 One point should always be kept in sight, always acted on, and 
 never forgotten, which is, that all our ships should be made as 
 efficient as possible, and no means left untried by which sufficient 
 promise of success is given ; and this is more particularly the case 
 with our huge and costly ships of war, costing enormous sums for 
 hulls and engines, and also for wages, coals, stores, &c., and as yet 
 exposed to the damage and loss caused by fouling and corrosion, 
 for which none of the remedies tried have in any way proved an 
 efficient antidote. 
 
 Failures often prove the cause of ultimate success, inasmuch as 
 they necessitate a proper study and investigation of the causes 
 which lead to them, and these when once arrived at may be said to 
 afford the key to their remedy or prevention if common sense be 
 
80 THE FOULING AND CORROSION OF IRON SHIPS. 
 
 called into requisition and aided by some practical knowledge and 
 experience on the subject. 
 
 To obtain a simple, practical, and efficient mode of attaching 
 plates of metal or sheathing to the hulls of iron ships, without 
 increasing the cost of construction or damaging the hull of the 
 ship, has been a desideratum ever since the introduction of iron 
 as a material for construction; and its rapidity of fouling and 
 corrosion gave unmistakeable proofs of the vital importance of 
 getting over these hitherto most formidable difficulties. 
 
 Although many plans more or less ingenious or impracticable 
 have been patented or proposed of late years, there can be no doubt 
 that the plan invented and patented by Mr. T. B. Daft, C.E., is 
 the one which fulfils all the various requirements in the fullest and 
 most satisfactory manner, and this, too, without incurring the 
 slightest drawback, difficulty, or disadvantage, by its employment. 
 
 The value of such an invention, especially as it is of a thoroughly 
 practical and efficient description, may be well estimated from the 
 following remark of Captain J. H. Selwyn, of the Royal Navy, that 
 " the problem of keeping a ship's bottom clean is one of the very 
 greatest importance." 
 
CHAPTER VI. 
 
 CORROSION. 
 
 Corrosion, or the gradual destruction of the iron hull of a ship 
 by the action of the sea- water, is a most formidable and serious evilj 
 as it involves the gradual -weakening and destruction of the ship, 
 and the extent of its insidious and certain action is not immediately- 
 discoverable unless a ship be docked and the hull carefully and 
 minutely inspected. The discovery of its action does not, un- 
 fortunately, prove its prevention, for although every precaution 
 may be taken to rectify the damage -where it may be discovered, it 
 -will not prevent this fatal action going on somewhere else ; thus, 
 in a short space of time, a ship may be so weakened and injured 
 over a considerable portion of its hull as to be far from seaworthy, 
 and there can be no doubt that many an iron ship has foundered 
 from the ill effects of this action, and from its having proceeded 
 more rapidly in some portion than had been the case elsewhere. 
 
 The corrosion of the iron hull of a ship is admitted to be of 
 great moment ; to protect the plates is of the greatest importance. 
 Paints are of little use, for though above water, if the paint should 
 be rubbed off, it can be laid on again, under water this cannot be 
 done without docking or grounding the ship ; consequently the iron 
 must be left exposed to this destructive action until an opportunity 
 can be afforded for so doing. It is a well-known fact that all parts 
 of a ship and each plate in the hull do not corrode equally or in a 
 similar manner, for which reason it is difficult to find out its 
 extent, except by a minute and careful examination over the whole 
 extent of the hull both inside and out. Iron plates, for example, 
 will corrode in large patches several inches in diameter, others 
 in a number of small holes or pockmarks, eating deeply into the 
 plate and forming small pinholes through itj in other cases 
 corrosion will attack the rivets, and the plates will be comparatively 
 free ; but be this as it may, the serious and alarming character of 
 the disease cannot for a moment be doubted, nor the importance 
 of finding and applying a remedy, or, better still, a means of pre- 
 vention. 
 
 The corrosion of the iron htill of a ship is due to two causes : 
 first, the destructive action of the salt and other matters contained 
 
 6 
 
82 THE FOULING AND CORROSION 
 
 in the water, which cause the oxidation or gradual destruction of 
 the iron ; and secondly, galvanic action caused hy the presence of 
 copper, yellow metal, or other material of greater power in the 
 galvanic scale, which causes the action set up to be concentrated 
 on the iron composing the hull of the ship, and results in its far 
 more speedy destruction and injury than when exposed to the 
 action of simple oxidation, added to which it is far more difiScult to 
 counteract. 
 
 The first, or the action of the sea- water on the iron, is increased 
 by the presence of fouling and the decomposition of the animal and 
 vegetable matter of which it consists, the products of this decom- 
 position greatly assisting the action. Mr. Hay, the Admiralty 
 chemist at Portsmouth, stated at the Institution of Naval Archi- 
 tects, in 1863, that " The decomposition of animal matter which 
 takes place whilst attached to the bottom is most destructive to 
 the iron." 
 
 The oxidation of an iron hull does not always proceed with 
 regular rapidity, nor does it confine itself to any particular portion, 
 but varies in both according to circumstances. For instance, in 
 fresh water, certain conditions exist which are not found in sea- 
 water, and also the difference of temperature is found to have a 
 great influence on its rapidity of action. In sea-water it is gene- 
 rally found to be much more active, from the variety of substances 
 contained therein exerting a much more powerful chemical action, 
 and this increases greatly with the temperature of the water in 
 which the ship floats. 
 
 Captain J. H. Selwyn, R.N., having had some experience on the 
 coast of Africa of the rapidity of corrosion in the heated water of 
 the tropics, says, "An iron rudder in a ship which I commanded was 
 so hung by the constructors, through want of knowledge of 
 galvanic action existing at that time, that it was hung between two 
 metal points in connection with the copper of the ship; that action 
 was so intensified that in eight months there was not one ounce of 
 the iron plate of the rudder which was not decayed, and which 
 was not in the form of red oxide. That is a fact which shows that 
 galvanic action is capable of going on." 
 
 The 'Times' of the 18th November, 1864, stated that "When 
 docked at Devonport the bottom of the " Achilles " iron-clad was 
 found to be not only foul, but to have many of the plates left com- 
 pletely bare of the composition, and corrosion had in many cases 
 eaten away the plating to the depth of from one sixteenth to one 
 tenth of an inch "! 
 
 The insulation or prevention of corrosion of armour-plates and 
 the iron hulls of ships has, up to a very recent period, baffled 
 every attempt that has been made to obtain such a desirable 
 end J but experience has shown that this has resulted more from ' 
 
or IRON SHIPS. 83 
 
 the want of a thorough comprehension and study of the principles 
 involved in corrosion than in any practical difficulty in doing it 
 ■when they are understood. 
 
 Nothing in the shape of a plaster or composition has yet been 
 discovered to effectually guard against the destructive action of 
 corrosion, or to prevent the fouling of the bottom of iron ships for 
 any length of time — nine to thirteen months being the longest 
 period any of the compositions will last on a ship's bottom without 
 renewing ; but requiring " hogging/' however, during that period. 
 And a little consideration of the subject should show that neither 
 of these is the best plan or system by which it is most likely to 
 be obtained. 
 
 The following examples illustrating the rapidity and extent to 
 which this evil of corrosion extends will amply prove the necessity 
 of at once taking means for preventing it. 
 
 The " Grappler," in less than three years from the date of the 
 order for her building, was so corroded that a hole of five inches 
 in diameter was discovered in her bottom ! 
 
 The " Jackal" was coated with red lead in May, 1847, and when 
 docked in April, 1848, the plates and rivets were found corroded 
 to such an extent that it was necessary to remove some 200 de- 
 fective rivets, and to punch holes in the corroded parts of the plates, 
 and plug them up again where they had suffered most from corro- 
 sion. 
 
 The '' Antelope," which had been to the coast of Africa, was 
 docked on her return, fifteen months after her former painting, 
 and the iron was found much corroded and many rivets had to be 
 removed and replaced. 
 
 The " Harpy," which had been four years on the south-east 
 coast of America, when examined on her return, was found to have 
 the plates much corroded; flakes from 4 inches to 6 inches in 
 diameter, and fths of an inch to 4- an inch in thickness, were 
 removed, and numbers of rivets had to be replaced. 
 
 The " Bloodhound," on her return from a foreign station, was 
 found to have corroded so extensively as to require a new bottom, 
 which was given her. 
 
 The " Jackal " founded at Greenock, from the corrosion having 
 eaten through the plates apparently unnoticed. 
 
 In 1863, some of the plates in the " Fairy," H.M. screw-yacht, 
 were found to be eaten nearly through, the mischief having pro- 
 gressed unknown and undiscovered ! 
 
 The " Myrmidon," iron steamer, belonging to the Royal Navy, 
 was found, when at Fernando Po, some years since, to have 
 her bottom plates so corroded that they were said to be " eaten 
 through like a colander," and the ship was in consequence con- 
 demned. 
 
84 THE FOULING AND CORROSION 
 
 The ' Mechanics' Magazine/ of January 5th, 1866, states that 
 " a discovery has been made at Toulon, where the iron-plated 
 frigate ' Provence ' is undergoing repairs, which shows the 
 danger that menaces the entire iron-coated fleet of France. The 
 ' Provence ' was fitted out for sea only fifteen months since, and 
 already a great number of her plates were nearly consumed with 
 rust. The Director- General of Naval Architecture is of opinion 
 that if a composition be not discovered to prevent the action of 
 rust, the iron-plated fleet must be renewed every five years I" 
 
 Chemical knowledge shows it to be highly dangerous to allow 
 copper in any shape to come in contact with the immersed portion 
 of the iron hull of a ship under any circumstances. It is totally 
 useless in keeping an iron ship clean, whilst it causes an action 
 which eats away the plates and rivets, and although insulation 
 may have been made perfect whilst in dock or on the slip, still this 
 state it is utterly impossible to maintain whilst the ship remains 
 in use. The very water itself in which the ship floats becomes a 
 conductor between the metals, and although paints may be em- 
 ployed to maintain insulation and prevent galvanic action, yet any 
 spot from which the paint may be rubbed off and the water can 
 reach, immediately becomes a starting-point or nucleus for the evil, 
 and it is equally certain that the loss and destruction of the ship 
 become merely a question of time. 
 
 Though the most rudimentary works on chemistry point out 
 that the contact of two metals when immersed in a liquid sets up 
 galvanic action, and results in the destruction of the weaker metal ; 
 and although scientific men of the highest eminence, both in their 
 published works and lectures in this country and abroad, have shown 
 this to be the case, nay, have even pointed out the fact that two 
 pieces of a similar metal cut from one bar will, when brought into 
 contact and immersed in fluid, develop galvanic currents, it is 
 nevertheless a fact that many men professing to be scientific and 
 learned in these matters, have actually decided that this is not the 
 case, and in consequence set their wits to work to devise a mode by 
 which copper or yellow metal may be attached to iron hulls ; and 
 one " engineer " actually proposed to attach one to the other, with 
 no insulating material whatever between them. It is not a little 
 surprising, when the results of attempts in this direction are 
 analysed, to find the amount of quackery which in some cases is 
 tolerated and in others encouraged, and the ipse dixit of such indi- 
 viduals at once accepted as conclusive, because, although practice 
 shows they do not, theory says they ought to know all about it. 
 
 Galvanism is the term applied to express a peculiar form of 
 electric agency, developed under particular circumstances, and 
 productive of certain effects upon bodies which do not usually 
 result from the ordinary modes in which excitation is practised ; 
 
OF TRON SHIPS. 85 
 
 in fact, it may be termed chemical electricity, as against the 
 mechanical, magneto, or frictional system. 
 
 The process usually adbpted in order to obtain galvanic elec- 
 tricity is to expose two plates, or portions of different kinds of 
 metals, to the action of a fluid capable of exerting some kind of 
 chemical action on one of the plates or metals, whilst at the same 
 time it does not affect, at least in a similar manner, the other 
 plate or metal, and then establishing a communication between 
 the metals either by their direct contact with each other, or by 
 the intervention of some conducting medium. 
 
 The result of this is, that a quantity of electricity is set in 
 motion, with a continuous action so long as the conditions 
 above described remain in force, and produce changes in the 
 composition of bodies which can be accomplished by no other 
 means. 
 
 It is now a well-established fact that galvanic action can be 
 established between two pieces of a similar metal ; and Captain 
 Selwyn and others have found that two pieces of iron cut from the 
 same plate or bar produced so strong a current as to " deflect the 
 galvanometer to 90°.'" 
 
 He also related that he could "take one part out of a plate 
 strongly negative, and another part strongly positive, a current 
 passing which is capable of producing an enormous effect." 
 
 Mr. Rae, iron shipbuilder, remarked from his experience, 
 "that in taking two pieces of iron from the same plate, and 
 putting them into the same water, I have shown a current existing 
 between them." 
 
 Captain Selwyn remarked, at the Institution of Naval Architects 
 in 1864, " I have shown before another institution that there are 
 no two pieces of iron, not even if they are cut from the same bar, 
 or any two woods, between which galvanic action does not or 
 cannot take place ; and though the intensity of action in a ship be 
 small, the surface operated on is so large as to be capable of pro- 
 ducing most insidious and dangerous effects." 
 
 It was observed when the " Shannon," Captain Broke's ship in 
 the celebrated action with the " Chesapeake," was examined, that 
 the oak trenails had destroyed the fir planking for two or three 
 inches round the trenail holes. 
 
 In 1831 Robert Dickinson patented improvements in the con- 
 struction of metal ships, and, when the same are constructed 
 wholly of iron, a means of covering them with copper, by the 
 intervention of a non-conducting plank covering between the iron 
 and the copper. 
 
 For applying this copper sheathing, thin planking was to be 
 wrought all over the surface of the bottom, and attached to it 
 either by screws from the inside, or by short bolts with their heads 
 
86 THE FOULING AND CORROSION 
 
 set deeply into the wood, and secured inside by nuts. The copper 
 sheathing was then to be applied in the ordinary manner. 
 
 In 1841 Mr. E. Mallet patented coating iron with an alloy of 
 zinc, mercury, and potassium or sodium, to prevent corrosion, and 
 then covering the whole with some poisonous paint ! 
 
 In 1852 Mr. A. Wall patented the application of mercury, or 
 solutions of the same, to the hulls of iron ships. 
 
 The use of mercury or quicksilver as an anti-fouling, anti- 
 corrosive! compound, has been again patented since, and some 
 considerable attention directed towards itj but here again is a 
 more dangerous material in exciting galvanic action than copper, 
 proposed to be placed in contact with the inferior metal, iron, out 
 of which the hull of the ship is composed ! 
 
 Mr. Bakewell, in his ' Manual of Electricity,' places mercury 
 fourth on the list, copper being fifth, and iron eighth; conse- 
 quently, a few moments' reflection, or a proper knowledge of the 
 subject and the causes of chemical action, would not have suggested 
 the application of a more powerful material than copper (the in- 
 jurious effects of copper being known from experience) to the iron 
 of a ship's hull. 
 
 In a letter to the ' Standard,' which appeared in that Journal of 
 the 7th January, 1867, Mr. P. N. Gisborne, the patentee of a 
 mercurial paint or ointment, stated " that the anti-corKosive and 
 anti-fouling paints (as patented by myself) effectually prevent the 
 hull from fouling, and the iron from corrosion," and in the con- 
 cluding part of the same letter he says, " when applied in its pure 
 state and without adulteration, I do not hesitate to say that I will 
 guarantee it to protect the bottoms of iron vessels from fouling, 
 and the iron from corrosion." 
 
 The results of the trial of this and several other plans on the 
 "Valiant" iron-clad during a period of eighteen months, as 
 described at pages 71 to 73, in the report of the ' Standard ' corre- 
 spondent, who saw the ship in dock, and also from the correspon- 
 dent of the ' Times ' of Jan. 11th, 1867, are the best answers to this. 
 
 Copper, in whatever way it may be applied, is certain to injure 
 the iron huU of the ship ; and no matter how scientifically and 
 carefully insulation may be carried out whilst the ship is in dock 
 or on the ground, it is utterly impossible that the combination of 
 circumstances to which such a ship is exposed when employed, can 
 enable this state of insulation to be maintained for even a single 
 day. It is an inexorable and certain law of nature that salt water, 
 iron, and copper, shall set up galvanic action, the infallible result 
 being the destruction of the iron ; and though it is not near so 
 powerful and rapidly destructive an action as would be obtained by 
 the use of sulphuric acid, in place of the salt water, yet it is not 
 the less certain nor the less fatal in its results. 
 
OF IKON SHIPS. 
 
 87 
 
 Fig. 2. 
 
 The wood sheathing, by the absorption of the moisture from the 
 surrounding water, becomes at once a conductor for the galvanic 
 power from the iron to the copper, or vice versa, and however care- 
 fully it may have been insulated at first, the straining and working 
 of the ship, the blows of the sea, the friction or bumping of barges, 
 boats, or against wharves, or piers, &c., the 
 wash of the water over the copper sheathing 
 and iron hull, the contact of the iron cable, 
 nay, even the contact of a wetted rope, or 
 the head of a single bolt, will each and all of 
 them quickly and surely destroy this insula- 
 tion, and set up or permit this destructive and 
 fatal action; in fact, it may be safely said 
 that maintaining insulation in practice under 
 these circumstances is an utter impossibility, 
 and attempts to perpetuate such a serious evil 
 should be at once discountenanced and pro- 
 hibited. The action of oak-wood in a timber 
 ship on iron bolts is shown in fig. 2, and 
 there is reason to believe that wherever iron 
 is used in fastening together the portions of a 
 wooden vessel used in salt water, that similar results take place. 
 
 It is well known that a wetted string makes a far better con- 
 ductor for electricity than whilst it remains dry j and that when 
 Franklin was using a kite for obtaining the electric fluid from the 
 clouds, as the rain wetted the string so the fluid passed more freely 
 than it did when dry. There can be no doubt that the water in 
 the wood sheathing, or other material on which the copper of an 
 iron ship is attached, and which is in contact with the iron hull 
 and the copper sheathing, acts in a similar manner to the wetted 
 string of the kite. At any rate, however it may occur, we have 
 still the fact that the copper sheathing does act injuriously on the 
 iron hull in spite of the absence of actual metallic contact, giving 
 thereby abundant proof of the serious results which do not fail to 
 attend the employment of these two metals when immersed to- 
 gether in sea- water. 
 
 The author has found, when using a galvanic battery to the ends 
 of the wires of which balls of sponge were attached, that the shocks 
 were given with much greater power when the sponges were wetted 
 than when they were dry, which seems to prove that the water acts 
 as a conductor of the fluid. 
 
 It is also well known, in the case of the telegraph wires, that 
 when the damp is condensed on the inside of the insulator, and is 
 in contact with the wire, that the fluid uses this dampness or wet 
 surface as a bridge Or path to escape from the wires, and so pass 
 off to the ground. 
 
88 THE rOULING AND CORROSION 
 
 The rules of Lloyd's Committee allow irow-fastened ships to be 
 classed in the same manner as copper-fastened ships, " so long as 
 they remain unsheathed with copper," and provided that they are 
 in all other respects constructed in accordance with the rules. 
 
 Mr. Bakewell, in his " Manual of Electricity/' published in 1859, 
 gives. the metals that excite electricity by their mutual action, 
 ranged in the following order, those placed first acting in reference 
 to those beneath as copper does to zinc : 
 
 1. Platinum. 4. Mercury. 7. Tin. 
 
 2. Gold. 5. Copper. 8. Iron. 
 
 3. Silver. 6. Lead. 9. Zinc. 
 
 Any two of the foregoing series will constitute what is termed a 
 voltaic current. Thus, zinc will excite voltaic action in combina- 
 tion with iron ; iron will take the place of zinc when combined 
 with tin ; and tin will take the place of iron when combined with 
 lead or copper. The energies of these combinations increase as 
 the metals are more distant from each other in the scale. Thus, 
 the most powerful practical combination is that of zinc and pla- 
 tinum, the former being the most corrodible, and the latter the 
 least corrodible of the ordinary metals. 
 
 M. Radermacher observed, at the Institution of Naval Archi- 
 tects, in 1866 — " I believe that iron and copper are two dangerous 
 elements to have together in sea-water, and I believe that to pro- 
 duce galvanic action does not need contact of two metals ; but I 
 believe that even wood saturated with salt water will form a great 
 conductor, and produce galvanic action." 
 
 Mr. Murray remarked, at the Institution of Naval Architects, 
 in 1867, that the " salts of copper," which are used in some of the 
 " anti-fouling" compositions, do " not prevent fouling ; the copper 
 salts decompose in sea-water, they injure the iron by galvanic ac- 
 tion, and do not keep clean more than four or six months." These 
 he gave as the results which have been observed by him during 
 many years at the port of Southampton. 
 
 The action of other metals on iron seems, as a whole, to be but 
 little thought of, though their results often come under notice. 
 For instance, the fixing to the stone of iron railings with lead is 
 still followed, though most people must have seen its ill effects ; 
 and all railings which have been so fastened for some time will be 
 found to be greatly damaged, or else almost eaten away just where 
 the lead touches them. 
 
 Even steel and cast iron will exercise a similar action on wrought 
 iron, that of the cast iron being more powerful ; and it seems that 
 the wrought iron is generally electro-positive with these other me- 
 tals, and the result is, that it suffers in proportion. 
 
 Sir Humphry Davy ascertained that when two metals in contact 
 are immersed in a saline solution, an increased action takes place 
 
or IKON SHIPS. 89 
 
 on one of the metals, whilst the action of the solution on the other 
 is diminished. Copper, for example, undergoes corrosion in sea- 
 water j but when zinc is in contact with it, the corrosion of 
 the copper ceases, and the destructive action is centred on the 
 zinc. 
 
 The " protectors" devised by Sir Humphry Davy for preventing 
 the loss of copper sheathing by exfoliation, consisted of a mixture 
 of iron and zinc, which were attached in oblong slabs rounded off 
 at the edges to different parts of the bottom over the copper sheath- 
 ing ; and the result was, that the exfoliation of the copper was most 
 effectually prevented, and the galvanic action transferred to the 
 " protectors," which became quite soft, and the metals, iron and 
 zinc, were quickly destroyed, the copper meanwhile becoming 
 dreadfully foul. 
 
 It is stated in the 'Mechanics' Magazine' for 1824 that "in a 
 recent trial made on boats, it was found that the copper on their 
 bottoms, which had protecting iron attached to it, became covered 
 with animalculae, which adhered so strongly to the copper that they 
 could not be removed even by a broom." 
 
 Professor Faraday has remarked — " The association of iron also 
 with other substances, if metallic, will much affect it ; thus a wharf 
 of cast iron might occasionally be greatly injured by making fast 
 to it vessels that are coppered, using iron cables." 
 
 Dr. Medlock, F.C.S., gives his opinion that " copper in any shape 
 whatever, whether in the form of oxide or of salts of that metal, 
 would exert a powerful corrosive action on the iron with which it 
 came in contact ; the copper salt would be reduced to a metallic 
 state, and for every equivalent of copper reduced a corresponding 
 equivalent of iron would be oxidized and destroyed. Although the 
 action might not be immediately perceptible so long as the coating 
 remained sound, yet I believe that the mischief would be constantly 
 and silently going on, and be discovered only when the iron is 
 seriously injured. I would therefore advise you not even to think 
 of using copper in any shape as a paint for iron ships." 
 
 Dr. H. M. Noad, F.R.S., speaks of having "arrived at the con- 
 clusion that no compound containing copper can long resist the 
 action of sea-water, and that in whatever form that metal may be 
 contained in a pigment, it would eventually take the form of oxi- 
 chloride, which salt would undergo such a decomposition as to lead 
 to the deposition of metallic copper in a thin porous state upon the 
 exposed portions of iron, particularly on the rivets, and that, under 
 such circumstances, a rapid corrosion of the iron must take place. 
 Copper in any form ought not to enter into the composition of 
 any substance having the object of protecting the bottoms of iron 
 ships." 
 
 Dr. Normandy, F.C.S., speaking of the decomposition of salts 
 
90 THE FOULING AND CORROSION 
 
 of copper in contact with iron, remarks that copper paint is not at 
 all " suited to the painting of iron ships." 
 
 Mr. Scott Russell remarked at the Institution of Naval Archi- 
 tects, in 1863, respecting the employment of copper on the sub- 
 merged portions of iron ships, " There will be chemical action of 
 some kind unless very serious precautions are taken." 
 
 Captain J. R. Engledue, who was formerly connected with the 
 steamers of the Peninsular and Oriental Company at the port of 
 Southampton, states that " I have at various times tried prepara- 
 tions of copper on iron ships, and in every case found the iron and 
 rivets damaged." 
 
 Mr. Lamport said, at a meeting of the Institution of Naval 
 Architects, " If iron and copper be combined in an acid or sea- 
 water, iron, being more electro-positive than copper, is chemically 
 decomposed, or, to use a more common phrase, is 'corroded.' 
 The galvanic current passing from the iron. or generating metal to 
 the copper as the receiving metal changes the condition of the 
 latter from a naturally electro-positive condition to one relatively 
 negative. The metal thus rendered electro-negative by the gal- 
 vanic current becomes proof against the action of the fluid as a 
 chemical agent. No decomposition takes place, and it assumes the 
 condition of a 'protected' metal, while the more positive one is 
 still more rapidly eaten into and decomposed by the stimulated 
 chemical action. If, in place of copper and iron, we take iron and 
 zinc, the same process takes place, reversed, however, as regards 
 the iron. Zinc, being more positive, is chemically disposed, and 
 the current passing to the iron renders it negative, and conse- 
 quently insoluble or ' protected.' " 
 
 When copper sheathing was first applied to iron-fastened ships, 
 it was soon found that the iron bolts became rapidly oxidized from 
 the action of the copper ; and although many plans were tried to 
 obtain insulation, no success attended these efforts, and in con- 
 sequence mixed or yellow metal, or copper bolts and fastenings, 
 had to be employed in vessels which were to be sheathed with 
 copper or yellow metal. 
 
 The ' Western Times' in April, 1864, remarks, "We have great 
 complaints from nautical men of the destructive action of some of 
 the copper compounds used on the bottoms of our iron-sides. The 
 subject is of the utmost importance." 
 
 The numerous instances quoted in this work of the destructive 
 action of copper on iron hulls will prove that these complaints are 
 not without reason ; and it is greatly to be regretted that although 
 chemical laws show how fatal and certain this action is, that people 
 should obstinately persevere in trying to set these laws at nought, 
 and that they should be allowed to prove the fatUity of their efforts 
 by jeopardising the safety of our splendid iron-clads. 
 
OF IRON SHIPS. 91 
 
 It is said that the Spanish Admiralty tested various plans and 
 preparations of copper for three years, and having satisfied them- 
 selves of their injurious effects, and found that it was perfectly 
 impossible to prevent ahrasion and galvanic action, entirely 
 excluded them from their arsenals. If this be a fact, it speaks 
 well for the intelligence of those in power, and it is to be regretted 
 that others have not profited by their experience. 
 
 Captain Selwyn has well remarked that " it would be cheaper to 
 build our ships of copper, than to go into plans for making copper 
 bottoms to iron ships." 
 
 " The protection of an iron bottom,'^ says the ' Engineer,' " offers 
 a double difiiculty. It has not merely to be preserved from the 
 sea- weeds and barnacles, but also from bodily corrosion. A copper 
 bottom would indeed preserve the iron vessel from sea-weed, but 
 not from corrosion ; this.it would indeed enormously intensify." 
 
 The ' Standard ' of July 11th, 1865, speaking of iron shipsj well 
 remarks : " Upon those bottoms you cannot place copper without 
 the intervention of plank, and even then you cannot be for a 
 moment sure that the galvanic action of copper on iron has been 
 completely neutralised. Thus, copper, apart from the costliness of 
 the application, must as a matter of prudence be discarded from 
 iron bottoms. Then, if you adopt the coating of iron bottoms with 
 brass or glass, the brass or glass becoming incorporated with the 
 iron and presenting an imperishable surface to the water you 
 supersede the principle of exfoliation, the principle of the wasting, 
 and from sheer necessity secure the absence of corrosion at the cost 
 of inviting all the vegetable and animal life of high latitudes to take 
 possession of your iron bottom. Why copper or yellow metal on 
 a wood bottom keeps clean is not because vegetable and animal life 
 decline to touch them, but because the waste or exfoliation of the 
 yellow metal on the copper speedily gets rid of them. So the 
 getting rid of exfoliation or waste is practically the getting rid of 
 the possibility of keeping bottoms clean at all. The correct view 
 to take on the whole is, that as exfoliation or waste is the condition 
 of keeping bottoms clean, and as copper cannot be attached to iron 
 without a greater risk than that sought to be evaded through its 
 application, an exfoliating or wasting composition must be accepted 
 as a necessity and not a choice." 
 
 It is most remarkable that the destructive action of copper on 
 iron, either in contact with or proximity to it in salt water, is so 
 little understood or admitted, and more unaccountable that where 
 it is well known its advocacy should be persisted in by those who 
 should, and in some cases do, certainly know better. One weekly 
 so-called engineering paper, the ' Mechanic's Magazine/ at one 
 time writes thus : — " No means of attaching copper sheathing to 
 an iron ship, however ingenious, can be relied on to preserve per- 
 
92 THE FOULING AND CORROSION 
 
 feet insulation between the two metals under the ordinary condi- 
 tions to which a ship is exposed. A chance rub or a blow may at 
 any time convert a coppered iron ship into a huge galvanic battery, 
 in which the iron, the very body of the ship, is being destroyed." 
 Further on it states that the only metal that can be used with 
 safety for sheathing iron ships is zinc, it being the only one 
 " which it is practicable to use," because the zinc is " electro-posi- 
 tive "" to the iron, and " there is no reason to doubt its success." 
 
 At a later period we find this same journal writing as follows : — 
 "As to finding a substance whereto marine plants and animals 
 cannot adhere, we need not go far j that has been known to us, and 
 used by us these many years, viz., copper, or an alloy of copper, 
 and, as far as we know, there is no other substance that is efficient. 
 There is a widespread error existing in the minds of almost all 
 those who have turned their attention to this matter ; it exists where 
 we should think it ought not. It is thought that wherever two 
 dissimilar metals touch, there must be voltaic action set up. This 
 can only arise from want of experience in such matters. They 
 apparently do not know that three conditions are necessary to the 
 existence of voltaic action, viz., two dissimilar metals, and at least 
 moisture, speaking with reference to the sheathing of ships, for 
 other substances may take the place of metals." 
 
 It is enough to provoke a smile, if it did not give rise to other 
 feelings, to look over the recorded attempts of various persons to 
 employ copper or yellow metal on the bottoms of iron ships, with- 
 out at the same time encountering the silent and dangerous results 
 of galvanic corrosion. Each party professes to avoid galvanic action, 
 and talks loudly of the " perfect insulation ■" attained by his 
 peculiar method ; but even admitting for a moment that each of 
 them had attained the most perfect insulation possible, they each 
 and all forget that this is destroyed the moment the ship gets afloat 
 by the fact that the water in which the ship floats, from acting as 
 a conductor, is the best and most convenient means of instantly 
 destroying it. 
 
 In a discussion at the Institution of Naval Architects in 1864, 
 Mr. Lamport said, "Mr. Grantham makes light of the fact of 
 chemical action; but any gentleman who has had his money invested 
 in a ship in which iron is contiguous to copper, will corroborate 
 what I state, that even iron bolts, covered as they are over the 
 heads, are generally eaten away, and how ? Simply by the wash- 
 ing of the water up the sides causing a galvanic action between the 
 two metals, and thus producing the chemical action which leads to 
 so deleterious an efl^ect. Silently and persistently the mischief may > 
 be working, until its full eSect be manifested, but perhaps never 
 acknowledged in the total loss of the ship at sea." 
 
 Mr. Grantham stated that in a composite ship built with iron 
 
OF IRON SHIPS. 93 
 
 frames, wood-planked, and coppered, the result was just what we 
 should have supposed — the frames and plates in the inside of the 
 ship forming the stringers were found to be free from corrosion, 
 but the bolts were found to have perished, or were beginning to 
 perish, in consequence of their approximation to the copper." 
 
 Various as are the modes which have been proposed and adopted 
 for obtaining insulation of the copper or yellow metal used in 
 sheathing iron ships, in no case have any of the projectors alluded 
 to the fact that the water, washing over the unsheathed portion of 
 the iron hull, and being in connection or contact with the copper 
 or yellow metal, at once destroys this insulation ; and that from 
 this very fact being unknown, or at least unnoticed, the greatest 
 and most serious dangers arise. A ship sheathed with copper or 
 yellow metal, and assumed to be perfectly safe from galvanic corro- 
 sion because of the perfection of the insulation, or means employed 
 to produce it between the hull and the sheathing, may be kept at 
 sea or in use whilst this destructive action proceeds with fatal 
 rapidity and silence ; and the fact that no security has been or can be 
 obtained from any presumed insulation may be only found out 
 when it has proceeded too far to be checked, by the sudden failure 
 of the hull, or by its leaky state. 
 
 Several persons, so persistent in the belief that nothing but 
 copper or yellow metal will do for sheathing, and at the same time 
 admitting that copper or yellow metal produce serious effects when 
 in contact with iron in sea-water, have actually proposed "lining " 
 or covering one side of each sheet of the above metals with tin, 
 pewter, or some other combination ; and then when the " tinned " 
 or " pewtered " side is applied next the hull of an iron ship, " no 
 injury through galvanic action could arise." 
 
 It has been said that " some use a layer of wood between the iron 
 and the zinc plates with their fastenings ; whilst others use felt 
 in lieu of wood for the same purpose. Amalgamated zinc plates 
 are another variety of the same general principles, while several 
 inventors propose to cover or encase each iron plate with a thick 
 coating of other metals, such as copper or brass, by galvanic 
 action, the metals being precipitated upon the iron to any thick- 
 ness required !" 
 
 M. Roux, in his first attempt at preserving iron hulls and pre- 
 venting fouling, used a chemical composition or paint which could be 
 easily applied to a ship's bottom, but he soon found that a composi- 
 tion would not stand the friction of anchors, cables, ropes, and small 
 boats ; and to prevent the growth of vegetation he tried mixing 
 the salts of copper with the composition, or else throwing copper 
 filings on it whilst wet or fresh laid on. The result of all this trouble, 
 however, was that galvanic action was soon set up, and all his care 
 and trouble went for nothing. 
 
94 THE FOULING AND CORROSION 
 
 Mr. Lamport, at the Institution of Naval Architects, in 1864, 
 said — " Chemical action forbids the contact of copper or yellow- 
 metal sheathing with iron." 
 
 Captain Selwyn remarked, at the Royal United Service Institu- 
 tion, in 1864, that " with iron ships copper is out of the question ; 
 there is no possibility short of casing the entire ship by the galvano- 
 plastic process of preventing the excitation of a galvanic current 
 and the consequent rapid decay of the iron, which is the inferior 
 material in this galvanic couple. Even if the metals could be 
 separated the cold water would act as a conductor, and we have 
 to deal here with enormous quantity, though low tension ; there- 
 fore copper, or any other sheathing which is of metal or includes 
 metallic compounds higher or lower in the galvanic scale than iron, 
 is inadmissible." 
 
 The ' Steam Shipping Journal,' of October 30th, 1863, after 
 having given numerous instances of the fatal damage caused by 
 combining copper or yellow metals and iron in the hull of a ship, 
 and then exposing them to the influence of sea water, says — 
 " These demonstrated facts on so grand a scale will destroy many 
 theories, and are valuable to the shipping interest as a monitor, 
 when projectors are advising outside planking and copper sheath- 
 ing under water to iron hulls." 
 
 The same paper further remarks, in reference to the employment 
 of this principle by shipowners, and the serious results which would 
 inevitably follow, that such vessels " would fall to pieces in about 
 a year, supposing the galvanic process of decomposition were to 
 keep pace with the destruction actually proved to have taken place 
 in the four and a half inch plates of the " Royal Oak," and nothing 
 done to protect the upper part of the hull from this insidious 
 enemy." 
 
 It has been frequently urged that the copper or yellow metal, 
 when used as a sheathing for iron ships, will not produce any inju- 
 rious effects if carried above the load water-line; but, as the 
 ' Steam Shipping Journal ' has well observed, " All vessels roll at 
 sea, and heel over under canvas, therefore there must be a point 
 where contact takes place and galvanic action is generated. Our 
 ship-builders have to overcome this dif&culty before sheathing iron 
 hulls with copper can be safely and economically applied." 
 
 Supposing, however, that the most perfect insulation can be 
 obtained at the commencement, it will, if preserved, almost amount- 
 ing in practice to an impossibility, have the desired effect ; but 
 suppose a ship so sheathed touches the ground, or an anchor on a 
 foreign station, or on her outward voyage to a port where she 
 cannot be docked for examination, although not necessarily leakyj 
 or suppose she crumples up a sheet or part of a sheet of copper on 
 her fore-foot or bows by the friction of her cable, or any part of 
 
OF IRON SHIPS. 95 
 
 her hiiU, so as to allow a mere film of sea- water to touch the iron 
 skin, her destruction in a few months would he inevitahle, seeing 
 that the plates of the " Royal Oak " were eaten in to a depth of 
 five eighths of an inch in five months ! 
 
 An experiment for obtaining insulation was tried with a piece 
 of iron Q\" long, 3" wide, and -f-" thick, which was carried out in 
 the following manner : — Twelve holes each -^" di. x ■§■" deep, and 
 If" apart, were drilled on one side of this piece of iron, and into 
 each of these holes ebonite plugs or bushes were driven so that 
 they might form holding places for the nails, and prevent metallic 
 contact. On the face of the iron, and covering all the holes and 
 plugs, was placed a piece of stout tarred felt, over this a piece of 
 vulcanized india-rubber, and on this a piece of Muntz's yellow 
 metal, in which were holes corresponding to those in the iron, and 
 short nails of the same metal were then driven through these holes 
 into the ebonite plugs, each punching out a small disc of the rub- 
 ber and felt, and driving them down to the bottom of the hole. 
 By this plan the water was prevented from getting between the 
 felt and the iron, and it was" thought that perfect insulation was 
 most certainly obtained, and aU risk of corrosion from galvanic 
 action prevented. 
 
 This piece of iron thus prepared was sunk in the sea by order of 
 the Committee of the Royal Commission on Iron Plates, and left 
 there for twenty-eight weeks, or a little over six months, at the 
 end of which period it was taken out and the following results were 
 obtained : — " On turning back the yellow metal, rubber, and felt, 
 at one end, and drawing out some of the nails, it was found that 
 no water had obtained ingress between the felt and the iron, con- 
 sequently the iron was quite dry and presented its natural appear- 
 ance, no rust or corrosion beiiig apparent. On the under side of the 
 iron, which was not coated with the felt, and on which no yellow 
 metal was placed, as well as the edges of the iron all round, cor- 
 rosion had begun, and on the edges it presented the fibrous ap- 
 pearance of the mietal usual in such cases, whilst on the under side 
 it had begun to form holes, and the plate was considerably eaten. 
 This piece of iron in its state as taken out can be seen at the offices 
 of the author. 
 
 From this it would appear that, no matter how carefully insu- 
 lation may be made between the hull of the ship and the copper 
 or yellow metal sheathing, nor how soundly this insulation may be 
 maintained when at sea, still the water being in contact with the 
 copper or yellow metal sheathing and the iron of the hull also, 
 would be quite sufficient to cause corrosion; and it is totally 
 impossible in the case of a ship at sea to prevent the water forming 
 a connection between these two different metals, and causing this 
 most insidious, dangerous, and fatal action. 
 
96 THE FOULING AND CORROSION 
 
 The certain results of this course cannot be denied, and it is 
 greatly to be regretted that it should be carried out on so extended 
 a scale as it has been, and still be viewed with favour in those 
 quarters where its adoption is most likely to be countenanced and 
 its evils perpetuated. The cost of frequently stripping our large 
 iron-clads, in order to see how this action goes on, will be very 
 great, and the loss of time involved thereby will amount to some- 
 thing very considerable ; but the worst of it is that all will be going 
 on in spite of everything that can be done to prevent it. No pre- 
 cautions that can be taken with an iron-clad sheathed' with copper 
 or yellow metal whilst at sea'caw prevent this, or even limit its 
 sphere of action ; and until we can set at nought the inexorable 
 laws of nature this result will always follow. 
 
 It may be taken as a sure thing, that when the copper or yellow 
 metal sheathing on an iron ship fouls when at sea, the galvanic 
 action generated by the presence of the two metals in sea-water is 
 attacking the iron of the hull ; for if it expended itself in causing 
 the copper to exfoliate, no fouling would remain on it. Sir Hum- 
 phry Davy found precisely this result when he placed his iron 
 protectors on the men-of-war, and from a precisely similar reason, 
 viz., that the copper was preserved at the expense of the iron ; and 
 when these protectors were taken off, the copper again exfoliated, 
 and the fouling was removed. 
 
 Captain Selwyn has stated " that wherever you put copper and 
 iron together in a vessel exposed, not alone to the water of the sea, 
 but even to the moisture of the atmosphere, there you will inevit- 
 ably have a strong galvanic action. There is no knovm means of 
 stopping that." Speaking of the idea of obtaining insulation, or 
 the prevention of galvanic action by placing a skin of wood between 
 the iron hull and the copper or yellow metal, he observes — " There 
 is no part at which there is not a deposit of salt water upon it, and 
 that salt water is the conductor to continue the galvanic action 
 through." 
 
 The certainty with which galvanic action can be set up is not so 
 remarkable as the very small amount of materials required to gene- 
 rate it, the action not being dependent upon the quantity of surface 
 exposed to the water. For quantity and energy of action a large 
 surface is required to be exposed ; but galvanic action is not more 
 surely generated thereby, nor does it differ in its resultsy except in 
 intensity, whether it be one square inch or one square yard that is 
 exposed. 
 
 In this fact lies the great danger, for persons are too apt to 
 assume that because there does not seem any very striking appear- 
 ance of the conditions required to form a galvanic battery being in 
 existence, that therefore no importance need be attached to it, and 
 consequently the evil is suffered to exist and make sure and silent 
 
OF IRON SHIPS. 97 
 
 progress towards those very results they are so anxious to prevent, 
 and might have done, had they given proper consideration and 
 attention to the subject ; and it is only by some fortunate chance 
 that evil results can be prevented. 
 
 Mr. Bakewell states, in his ' Manual of Electricity,^ that " two 
 wires, one of platinum and one of zinc, each one eighteenth of an 
 inch in diameter, placed five sixteenths of an inch apart, and 
 immersed to the depth of five eighths of an inch in acidulated 
 water, consisting of one drop of oil of vitriol and four ounces of 
 distilled water, and connected at the other extremity by a copper 
 wire of eighteen feet long and one eighteenth of an inch in thick- 
 ness, yield as much electricity in little more than three seconds of 
 time as a Leyden battery charged by thirty turns of a very powerful 
 electrical machine in full action. This quantity is sufiicient, if 
 passed at once through the head of a cat, to kill it." 
 
 It is stated in 'Experimental Researches' that ''zinc and pla- 
 tinum wires one eighteenth of an inch in diameter, and about half 
 an inch long, dipped into dilute sulphuric acid so weak that it is 
 not sensibly sour to the tongue, or scarcely to our more delicate 
 test-papers, will evolve more electricity in one twentieth of a 
 minute than any man would willingly allow to pass through his 
 body at once." 
 
 Dr. Wollaston found that a single plate of zinc, with a super- 
 ficies of one square inch, when properly mounted and suspended in 
 dilute sulphuric acid between two copper plates of similar dimen- 
 sions, was more than suf&cient to ignite a platinum wire of 3-pVot^ 
 part of an inch in diameter, which formed part of the connection 
 between the two metals. 
 
 The ' Moniteur de la Elotte,' a French naval periodical, states 
 that when the " Gloire " was taken into dock the following phe- 
 nomenon, " which none on board the ship were aware of, showed 
 itself," and this was, that " the copper" sheathing, being brought too 
 close to the under- water armour-plates, had set up galvanic action, 
 which, acting like a voltaic pile, had greatly corroded the plates 
 below the water-line." 
 
 In the 'Standard' of May 1st, 1862, it was stated that "Foreign 
 Governments also now building iron ships of war and transports, 
 are fully alive to the importance of protecting the plates and rivets 
 of their future navy from premature destruction by using a com- 
 position paint containing no copper," and that some steamship 
 owners and companies "have long since tried preparations of 
 copper, and satisfied themselves of its destructive effects on iron 
 whenever the under-coating accidentally and unavoidably becomes 
 scratched up by chain cables, dock fenders, buoys, or floating wreck." 
 
 The 'Steam Shipping Chronicle' remarked that "it is the 
 opinion of practical and scientific men that any preparation con- 
 
 7 
 
98 THE FOUJ;ING AND CORROSION 
 
 taining copper must eventually prove injurious to the rivets and- 
 plates of iron ships^ whilst its efficiency in keeping off shelly in- 
 crustation longer than any other composition is by experiment 
 found to be a fallacy/^ 
 
 The ' Shipping and Mercantile Gazette ' of the 5th December, 
 1862, stated that the "French floating battery 'La Gloire' has 
 lately been examined, and found to be seriously injured by the 
 action of copper on her iron plates, the whole of which below the 
 water-line will have to be removed, being converted into a kind of 
 plumbago by galvanic action. We had occasion, some time since, 
 to call attention to the extraordinary state of Her Majesty's ships 
 "Triton" and "Sharpshooter." On their being docked for ex- 
 amination, the iron plates were in some places reduced to the 
 thickness of writing paper, and in the case of the " Triton,'' the 
 scrapers actually went through the plates when removing the tons 
 of oysters, barnacles, &c., attached to her bottom. It appears that 
 this ship had been coated with a preparation of copper, and the 
 destruction of the plates and rivets arose from galvanic action on 
 the exposed surface of the iron where the under coating had become 
 rubbed off under the bows and forefoot, and along the light load 
 water-line. The salvation of this ship from foundering was no 
 doubt occasioned by the adhesion of the shell-fish." 
 
 In the ' Standard' of October 27th, 1863, it was stated that the 
 " Royal Oak," of iron sheathed with wood and coppered, when the 
 water was emptied from the dock in which she was placed, dis- 
 covered " a most remarkable appearance, which created no small 
 consternation among the authorities. The armour plates adjoining 
 and in contact with the copper sheathing were found to be eaten away 
 by galvanic action, presenting a series of corroded holes running 
 into each other, from half an inch to five eighths of an inch deep. 
 Some of the plates contained no less than 188 of these, whilst none 
 had less than 40. Several detached holes are of an oval form, as 
 though gouged out with a steel tool of all sizes, from that of the 
 bowl of a salt spoon to that of a gravy spoon, and of equal depth ; 
 and some of the heads of the bolts had become recessed to the 
 depth, size, and appearance of the bowl of a small ladle. Numbers 
 of the holes had run into one another to the extent of five or six 
 feet, five eighths of an inch deep and upwards, altogether presenting 
 one of the most remarkable appearances ever witnessed. This ship 
 has only been about eight months in the water ! These holes and 
 corrosion appear to have occurred wherever the red lead or under 
 coating had been rubbed or washed off." 
 
 The ' Times ' of October 28th, 1863, in remarking on this, said, 
 " Wherever the least abrasion or friction has taken place, and the 
 red lead or composition has been rubbed off from the surface of 
 the plates, galvanic action has been in full force. This is remark- 
 
OF IRON SHIPS. 99 
 
 ably evident in one part — the hook, several feet long, which keeps 
 the accommodation ladder in its place, is fastened to the ship's side 
 by an eyebolt ; when not in nse the end drops below the level of 
 the sea between plates 11 and 12, it has been allowed to sway 
 about fore and aft, and has thus worked off the composition, and 
 the action of the copper has in consequence had full effect here ; 
 a portion of a circular groove exists in each iron plate, each portion 
 being two feet six inches long in the sweep, and about three eighths 
 of an inch in depth. In some places, just at the junction of the 
 iron with the sheathing, the edges of the iron plates are corroded 
 for lengths of six inches to a foot, and in one place under the 
 quarter this kind of corrosion extends to a length of ten feet." 
 
 As an instance of the results of the application of copper in any 
 form, when applied to an iron ship, may be cited the " Triton," 
 which had been coated over with a preparation of copper, and when 
 taken into dock at Keyham it is said that " by the galvanic action 
 where the bitumen had gone off in flakes, the plates were in some 
 places reduced to the thickness of writing paper, the scrapers and 
 slices used for detaching the oysters, &c., going right through the 
 plates.-" 
 
 The ' Times' of November 17th, 1859, in referring to the results 
 on a ship which had been coated- with a preparation of copper, 
 says, " The result is considered as having incontestably proved that 
 preparations of copper are of little value in preventing incrustation 
 or fouling on the bottoms of iron ships, while their galvanic action 
 must sooner or later prove injurious to the rivets and plates." 
 
 The " Black Prince," in 1863, was coated on one side with the 
 copper solution of Mr. Hay, the Admiralty chemist, at Portsmouth, 
 and the other with the copper composition of Mr. Mclnnes. Five 
 months after she was taken into dock at Devonport, when the fol- 
 lowing very important results were obtained : — 
 
 " Both sides were much corroded, but the oxide of copper of Mr. 
 Hay seemed to have been less efficacious than the sulphate of Mry ' 
 Mclnnes. The sulphate of copper was the cleanest, there being less 
 weed and barnacles on it ; whereas on the side done with the oxi'de 
 of copper, thousands of small mussels were found adhering under 
 the lands of the plates, and the plates themselves, on the flat of the 
 bottom, were covered with coralline worm shells very thickly 
 incrusted." 
 
 It is a curious fact, and no less curious than true, that in spite 
 of all the experience gained of the ill effects of copper, however 
 applied, on the hulls of our iron ships, its use should be still per- 
 sisted in, and the serious evils and dangers which accompany it set 
 at nought ; but still such is the fact, for the author finds that the 
 ' Times ' of November 30th, 1864, announced that " Admiralty 
 orders " had been given for the " Prince Consort," iron-clad, to be 
 
100 THE FOULING AND COREOSION 
 
 coated with "copper and felt sheathing on Commander Warren's 
 plan, for trial "I The " Northumberland " also will be coppered. 
 
 It has been said that the reason why copper and yellow metal 
 are in such favour with the Admiralty as materials fit and proper 
 to be used for sheathing iron ships, is because there is a large 
 quantity in store at the dockyards, and therefore it ought to be 
 used! 
 
 Fouling, although a most annoying, expensive, and troublesome 
 evil, is not so serious and fatal a drawback as corrosion. This 
 latter involves the destruction and loss of the ship, whilst, if not 
 allowed to proceed so far, still it produces a diminution of the 
 strength of the hull, and renders the ship less sea-worthy and safe, 
 the results of its action being sure, silent, and hidden. An hidden 
 enemy is the most difficult to guard against, and the least able to 
 be attacked, and it is only by finding out what it is that causes the 
 corroding action in the hull, and using all and every means which 
 has been devised and science points out as being able to counteract 
 it, that any hope can be had of obtaining immunity from its fatal 
 and certain ravages. 
 
 The exfoliation of the surface being the action which keeps the 
 metal sheathing clean when placed on the hull of a wooden ship, 
 it must therefore be evident that what is required as a sheathing 
 for iron ships is a metal that is positive to iron, or will absorb the 
 galvanic action caused by the water and different metals being in 
 contact, and will therefore preserve the iron, which will exfoliate 
 or peel off sufficiently to remain perfectly clean whilst the ship is 
 afloat, in whatever climate she may be ; and be at the same time 
 capable of wearing some three to five years, without requiring 
 renewal. 
 
 Of all the metals known, and obtainable at a reasonable rate and 
 in sufBcient quantity,- zinc is the only one which, when in metallic 
 contact with iron, fulfils these conditions ; and for these and many 
 other reasons it stands pre-eminent as a preserver of iron both from 
 corrosion and fouling. The purity of the zinc, however, has an 
 important influence on its satisfactory performance, and also on 
 its successful application j and for this reason it becomes very 
 desirable that care and judgment be used in its selection, and 
 Careful tests be employed, to decide its applicability to this pur- 
 pose. 
 
 The protection afforded by the zinc to the iron is so perfect that 
 in all experiments the smallest "fay" or feather edge left from the 
 shears on the iron has remained in its original form, even after 
 twelve months' immersion in sea-water ; and it would seem to show 
 that, with ordinary care, there is no reason why the skin of iron 
 ships protected by zinc sheathing should not be indefinitely pre- 
 served. 
 
OF IRON SHIPS. 101 
 
 The advantages and importance in a national point of view of 
 having obtained a mode by which the bottoms of iron ships can be 
 kept as clean and free from fouling as a wooden ship sheathed with 
 copper or yellow metal, whilst at the same time the iron composing 
 the hull of the ship is preserved from corrosion or deterioration, 
 cannot be sufficiently estimated or too highly valued ; and it is 
 hoped that immediate steps will be taken to construct an iron 
 ship on this mode, so as to give a proper opportunity for realising 
 its benefits and advantages, as the enormous saving which will 
 accrue therefrom to the nation and the shipowner cannot be 
 questioned. 
 
 Captain C. P. Coles remarked, at the Institution of Naval Archi- 
 tects, in 1866 — " The finest and strongest iron vessels, with iron 
 bottoms, if sent unprotected to sea, would soon become useless and 
 dangerous." 
 
 It is very difficult to obtain accurate and authentic accounts of 
 the extent to which corrosion prevails amongst the ships of the 
 navy, or the merchant service, any cases of the sort being generally 
 kept very quiet, and remedied by removal of the plate or other 
 means ; but from time to time some of them get into the papers, 
 are noticed by a passing glance, and then forgotten ; it apparently 
 being assumed that there is no remedy for it in existence, nor one 
 to be devised, but that, like noise to motion, it is an inseparable 
 accompaniment of the iron ship. 
 
 There can be no doubt that the constant and continued failures 
 of the multitudinous "anti-corrosive" paints, putties, plasters, 
 glues, powders, pickles, and other nostrums, which have been so 
 persistently and loudly introduced to our notice, have done more 
 to perpetuate this belief and divert attention from the proper and 
 thorough investigation of the subject, than anything else; and as 
 Captain Selwyn has well remarked, in 1864, at the Institution of 
 Naval Architects — " When the chemist gives up the notion of 
 poisoning the barnacles, and the idea of coppering iron, he will 
 probably be able materially to aid the sailor in keeping his vesseFs 
 speed, when the naval architect has given it to her." 
 
CHAPTER VII. 
 
 IMPfiOVED CONSTRUCTION. 
 
 In this chapter the author has endeavoured to give a plain and 
 practical description of Mr. Daft's plan of construction and sheath- 
 ing of iron ships, and to examine it in all its bearings, with the 
 view of finding whether there existed any serious defects in its 
 principle, or any practical difficulty in carrying it out. It is hoped 
 that the results of his investigations will satisfy those most inte- 
 rested in the subject; and it seems to the author that nothing but 
 ignorance or prejudice can operate as a drawback to its most ex- 
 tended adoption. 
 
 Up to the year 1863, the most general plan of constructing iron 
 ships was that known as the "in-and-out" strake system, formed 
 by placing one or every other strake wpon the frames or ribs of the 
 ship, and the next or every other strake outside these, the lap or 
 junction of the edges being riveted, the result being a narrow 
 trough or space and a wide plate or strake in alternate widths, 
 and, when viewed endways, giving the appearance shown at a in 
 fig. 3. By this plan the ends of each plate in each strake formed 
 a " butt" joint, the laps being attainable only on the longitudinal 
 seams ; and these butts form always the weakest and most trouble- 
 some parts of the ship. 
 
 In the year just named, Mr. Thomas B. Daft, C.E., patented his 
 system of constructing and sheathing of iron ships and vessels, by 
 means of which many great and important advantages, hitherto 
 unattainable, are easily and readily secured; and there can be no 
 doubt that this system must be extensively adopted as its advan- 
 tages become known and appreciated. 
 
 The frontispiece shows the mode of construction and sheathing 
 patented by Mr. Daft; and it will be seen that each strake of 
 plating comes on the frames, instead of every other strake, as is 
 the case with the "in-and-out" strake system; thus doing away 
 with the liners and long rivets through plate, liner, and frame, 
 which are known to be objectionable, whilst both end and longi- 
 tudinal seams can be double or single riveted, as may be preferred. 
 The section, full size, shows the skin, teak, nail, and sheathing. 
 
THE FOULING AND CORROSION OF IRON SHIPS. 
 
 If it is preferred, the butt straps may be used in 
 stringers, placed on the frames, the plating coming 
 against them, and the spaces filled in with liners, 
 as shown at k, fig. 5 ; but this is not con- 
 sidered so good as when the plates are placed 
 directly on the frames, because this mode involves 
 the use of long rivets, which, as before stated, are 
 objectionable on account of the difficulty of making 
 a good job in closing them. 
 
 It is hardly to be expected that any new plan, 
 however good, simple, efficacious, or meritorious 
 it may be, should secure the support and approval 
 of all parties ; and accordingly, in -this instance, 
 numerous objections, none of which, however, can 
 be sustained for a single moment, have been urged 
 against it. 
 
 First, because this system abolishes the " butt" 
 joint and substitutes a lap, parties are found 
 to condemn it and prefer the "butf joints, 
 on which they " place great reliance." Next, 
 because some strips of wood are introduced be- 
 tween the edges of the plates, to form a hold for 
 the sheathing-nails, it is at once condemned, be- 
 cause they would work out, and, moreover, they 
 weaken the structure. Next, because each plate 
 becomes a " lap," and can be caulked all round, 
 no "butts" being required, it is objected to, be- 
 cause the ship cannot be so strong as when 
 " butts" are used, and, moreover, cannot be made 
 so tight. Next, because the joints of the plates 
 do not butt against each other, though the vessel 
 may be as strong in tension, she is much weaker 
 in compression. 
 
 It would be tedious to notice the frivolous ob- 
 jections which have been raised by some people ; 
 therefore it is proposed to confine attention to the 
 most weighty, especially as without due considera- 
 tion and a thorough comprehension of the prin- 
 ciple they may at first sight appear to have some 
 foundation. 
 
 Some persons, evidently without having duly 
 considered it, object to this principle of construc- 
 tion, alleging that it cannot be so strong as the 
 ordinary in-and-out lap and butt, because the 
 straps or welts are rolled as bars, and not as 
 plates, and from the strain being applied across 
 the fibre, instead of longitudinally with it, it must 
 
 long lengths as 
 Fig. 3. 
 
 r : I 
 
 & 
 
104 THE FOULING AND CORROSION 
 
 therefore be all that the weaker. It will be interesting just to 
 look into this view of the case, and see what grounds there are in 
 support of it. 
 
 Dr. Pairbairn relates that the results of his experiments on 
 Yorkshire, Derbyshire, Shropshire, and Staffordshire plates, when 
 tested in the direction of the fibre, and also across it, gave the fol- 
 lowing mean : 
 
 PER SQ. INCH. 
 
 Mean breaking weight in direction of fibre . 33"519 tons. 
 „ „ across the fibre . . 23"037 „ 
 
 Or a difference of strength of about TV^tj when tested across the 
 fibre, in favour of applying strains in that direction. No descrip- 
 tion is given of the mode in which the plates were arranged for 
 undergoing the tests, how the tests were applied, or what kind of 
 apparatus was used ; and it may be remarked that no other en- 
 gineer seems to have obtained results of a similar character. 
 
 Mr. David Kirkaldy, whose almost innumerable and patient in- 
 vestigations of the strengths of all kinds of metals are so well 
 known, tested 167 plates lengthwise of the grain or fibre, and 160 
 plates crosswise, and obtained the following results : 
 
 LBS. 
 
 Mean breaking weight in direction of fibre . . 50737 
 „ „ across the fibre . . . 46' 171 
 
 He experimented with a great number of makes of iron in various 
 forms, and he found a mean result of 9' 8 per cent, in favour of the 
 strain being applied with the fibre instead of across it. 
 
 Mr. Edwin Clark, in his experiments on iron for the Conway 
 and Britannia Tubular Bridges, obtained the following results from 
 his experimental tests of the plates : 
 
 TONS. 
 
 Ultimate breaking weight in direction of fibre, Exp. 1 = 19'66 
 
 Exp. 2 =30-2 
 
 „ „ across the fibre Exp. 1 = 16-93 
 
 Exp. 3 =16-7 
 
 From these results it would seem that there is a reasonable 
 ground for the objection, that strains across the fibre are not so 
 well resisted as when applied longitudinally, or in the direction of 
 the fibre ; and were it the fact that the straps could only be applied 
 so as to receive the strain across the fibre, there can be no doubt 
 that the objection of weaker construction would hold good. 
 
 It fortunately, however, happens that there is not the slightest 
 difficulty in so arranging the manufacture of the straps, that when 
 applied they shall receive the strain in the direction most favorable 
 to utilising the strength of the material ; and this is easily and 
 
OF IRON SHIPS. 105 
 
 readily accomplished by rolling them as plates, and cutting them 
 so as to have the fibre in the direction required, whereby this 
 objection is at once overcome, and the defect of construction, which 
 the use of ordinary rolled bars for this purpose would appear to 
 cause, is effectually removed. 
 
 This is quite in accordance with the directions of Lloyd's Com- 
 mittee, who state in their Rules for the Construction of Iron Ships, 
 " that all butt straps, or lining pieces to butts, be fitted with the 
 fibre of the iron in the same direction as the fibre of the plating to 
 which they are riveted." 
 
 Mr. Grantham, in his work on ' Iron Shipbuilding,' has plainly 
 shown the superiority of the " lap joint " over that of the " butt ;" 
 and it is well known that the "butt-joint" system, as applied to 
 carvel-built ships, was so imperfect and objectionable as to lead to 
 the almost universal adoption of the " lap," as exemplified in the 
 plan of " in-and-out " strakes. 
 
 The " butt " could never be made tight ; consequently the more 
 " butts " there were in a ship, the worse she would be for tight- 
 ness j for, do all that could be done, by no means could the "butt" 
 be made either strong or tight, nor could any amount of fitting or 
 caulking get over this difficulty. 
 
 The " lap," on the contrary, can be made tight by caulking, and 
 this is urged as one of its greatest advantages. That this is so, 
 must be evident to any one who is ever so slightly acquainted 
 with the construction of iron ships j and it is in consequence of 
 every plate being put on the frames, and forming a joint with all 
 " lap," that the superiority of Mr. Daft's plan of construction is 
 so great and manifest; and where this is not admitted it must 
 be attributed to ignorance or prejudice, or a total want of compre- 
 hension of the principle. 
 
 Mr. Grantham, in his paper on "Jointing and Riveting Iron 
 Ships," read before the Institution of Naval Architects in 1862, 
 says, " As regards the butt joints, it is notorious that in no place 
 do iron ships sooner show weakness than in these ; and in no part 
 of iron shipbuilding is the system so deficient. Supposing the two 
 edges of the plate are made quite true, there is no certainty of 
 their being brought and kept solidly in contact till the riveting is 
 completed; The slightest motion will separate them, or the 
 slightest projection will keep the joint open. All questions are set 
 at rest by the caulking tool — a flat chisel, which is passed over the 
 joint — knocking down the burr which has before been raised, and 
 closing the plates at the upper part of the joint. This system makes 
 the joint water-tight, but is so evidently defective in strength, that 
 no one ought to be satisfied with it." 
 
 Dr. Fairbairn has well remarked that "A single defective joint 
 may endanger the safety of a ship ; how much greater, therefore. 
 
106 THE FOULING AND CORROSION 
 
 must be the danger if the principle throughout be unsound^ and 
 the whole of the joints of an imperfect character !" 
 
 An iron ship well built, on Mr. Daft's patent principlcj becomes 
 far stronger than it is possible to make a similar ship on the ordi- 
 nary plan, besides being far tighter and safer in that respect, from 
 having no leaky " butts," and because each and every plate being 
 all " lap " can be caulked all round, and thus equal tightness 
 throughout secured. 
 
 The author has been constantly met with the assertion, that the 
 teak strips, which are put in in a dry and compressed state, and are 
 further expanded by the sheathing nails which are driven into it, 
 must work out, and could never be made to keep in. It will be 
 desirable to investigate the feasibility of this remark. 
 
 Mr. John Grantham, in his paper on the "Strength of Iron 
 Ships," read before the Institution of Naval Architects in 1860, 
 when speaking of a timber-hmh ship, says, " Each bolt is a fixed 
 point, the seams being in constant motion. Now, in an iron ship 
 there is no such motion in the seams ; the outer shell is as nearly 
 as possible made into one plate." And he further says that " a 
 movement in a lateral direction is impossible." 
 
 At the Royal United Service Institution, in 1862, he stated that, 
 taking the lateral motion of the " Warrior," iron-built iron-clad, 
 " to be four inches on her entire length, I make the average open- 
 ing at the outer edge of each seam in the lengthways of the ship to 
 be about , 7,'ooo th part of an inch, or -^ th part of the thickness of 
 an ordinary sheet of writing paper, and in the inner edge of the 
 seam to be absolutely nothing but what may be allowed for in the 
 positive direct stretching of the plate between each frame at every 
 motion of the ship." 
 
 Were it possible for a ship to work so in a heavy sea that the 
 teak could come out, it would be evident that this could only 
 happen by the rivets becoming loose, in which case there can be very 
 little doubt that all tightness would be lost, and the ship most pro- 
 bably go to the bottom. If built with common "laps" and "butts," 
 and working to a similar degree, she M'ould, as a matter of course, 
 go to the bottom, " the water,'' as in the case of the unfortunate 
 " London," " would go in everywhere," and a similar result 
 speedily follow. 
 
 Dried compressed teak, driven tightly between the edges of the 
 iron plates, swelled up by the moisture, and further expanded by 
 the sheathing nails, is not like teak caulked into teak, but holds 
 with inconceivable tightness; and it is incomparably tighter, 
 sounder, and firmer than the oakum driven into the seams of a 
 timber-built ship, on which the civilised world have been depend- 
 ing for the last couple of thousand years. 
 
 The utmost straining in a heavy sea of an iron ship, built on this 
 
OP IRON SHIPS. 107 
 
 principle, so long as the rivets hold the plates together, will not 
 give sufficient alteration in the dimensions of the grooves to allow 
 the teak to leave them, they being so firmly held in by their ex- 
 pansion, the dove-tail form of the grooves, and the roughness on the 
 edges of the plates (which should be left as they came from the 
 shears) ; and there cannot be the slightest doubt but that they 
 would materially assist in keeping a ship afloat under such circum- 
 stances, in which without them she would inevitably go to the 
 bottom. Setting aside all other advantages gained by this system, 
 there is the most important one, which cannot be obtained by the 
 common system of plating, viz., that the seams are secured by an 
 additional elastic caulking by means of the teak strips. 
 
 Such a ship, well put together, the riveting firm, and all as an 
 iron ship should only be, cannot fail to prove one of the safest 
 structures afloat j and as a ship cannot be too tight, then if well 
 caulked with teak, elasticity, and all that can be desired, are most 
 certainly secured, and before long this will become an acknow- 
 ledged and established fact ; and it is most certain and undeniable 
 that if any yielding or motion do take place, it can only be from 
 the plates cracking or the seams opening, which could only result 
 from the failure of the rivets, and this would only happen in the 
 last extremity of an iron ship. In a sound vessel, well built and 
 riveted, this motion is impossible. In fact, no one who has had 
 any practical experience at sea can doubt for one moment that the 
 elasticity of the teak would more than compensate for these ex- 
 tremely small movements, and that its presence in the hull would 
 give great resiliency to the whole structure, and greatly diminish if 
 not altogether remove the unpleasant vibration caused by the screw. 
 
 It has been confidently objected, and this too by so-called 
 " practical " men, that by making the inside strake f of an inch 
 wide instead of 2' 6", the usual breadth in proportion to tonnage 
 of ship, as shown in fig. 3, that therefore the ship must be weaker, 
 although the sectional area of metal and mode of fastening remain 
 precisely the same ; but by none of these has any careful investi- 
 gation been made of the " reason why ■" they promulgate this 
 dictum, nor have there been any reasonable or sufficient data 
 brought forward in proof. 
 
 Because the teak is placed there to hold the nails it is dogmati- 
 cally asserted that it is put there to strengthen the ship, and that 
 because teak, which is a compressible material, is put there, the 
 ship is "immensely weakened thereby,^' but no calculation or proof 
 of the truth of this has ever yet been brought forward. 
 
 Now, according to the arguments adduced by them in support 
 of their opinion, namely, that because the " compressible material," 
 wood, is put in the grooves, the ship must be weaker, it follows 
 that if we take an ordinary iron ship of the usual in-and-out strake 
 
108 THE FOULING AND CORROSION 
 
 construction, and get a lot of dry teak planks, the thickness of the 
 plates and the full width of the inside strakes, compress them edge- 
 ways, and then jam them into the recess formed by the inside 
 strake (a, fig. 3), allowing the expansion of the wood to keep it in 
 place, that the ship must be weaker because of the " compressible 
 material," wood, being attached to the hull, but the sectional area 
 of metal being the same, and no holes in the plates inside ; a pro- 
 position, however, which would not be entertained for one moment 
 by a practical man who really understood the invention, or one 
 having any mechanical knowledge in his composition. 
 
 Mr. Grantham stated that "an iron ship would be greatly 
 weakened as a structure if made in that form with the joints, on 
 which I place great reliance, severed, and a soft material interposed. 
 The size of the plate too requiring the fastenings of the zinc to be 
 so far apart is, I think, an objection which cannot be overcome.^'' 
 
 Mr. Lamport asserted at the Institution of Naval Architects, in 
 1865, that "another objection to Mr. Daft's plan is the very 
 evident loss of strength in the ship, arising from the insertion of 
 the bands of wood longitudinally. We all know that when a long 
 structure is subjected to a Strain in the direction of its length, 
 every part in the middle must be brought closer and closer together 
 with a crushing tendency; as long as the narrow surface of the 
 iron butt joins upon iron, that tendency is met by the surface of 
 the iron itself. Mr. Daft's plan introduces a soft and compressible 
 piece of wood which must have a tendency to that extent to 
 diminish the longitudinal strength. Another evident disadvantage 
 of Mr. Daft's plan is, that inasmuch as it would have to be applied 
 to plates ten feet long by two feet broad, the sheathing would not 
 maintain itself on the vessel for any long time, as we find it neces- 
 sary to put the nails not more than four inches apart, in order to 
 maintain the cohesion of the copper sheathing. These points seem 
 to me to show that though this is a very ingenious arrangement — 
 and I must pay Mr. Daft that compliment — yet if we were to 
 build a vessel on this principle I do not think we should find her as 
 strong as though she were made of iron alone, and I fancy the zinc 
 would come off in large pieces." 
 
 It is a curious thing that this latter gentleman should not have 
 drawn the distinction between a wooden ship with copper or yellow 
 metal sheathing, and an iron one sheathed with zinc. That a 
 wood ship " works " and wrinkles the copper, yellow metal, or 
 other sheathing, is well known to any one who has taken the least 
 trouble to observe one in dock, or on a hard ; and from the very 
 nature of the vessel, being built of an assemblage of small pieces 
 of material, which it is impossible to fasten together with that 
 homogeneity of structure obtainable in an iron ship, it is utterly 
 impossible that there should be any other result. 
 
OF IRON SHIPS. 109 
 
 An iron ship will work in a seaway, but with a very diflferent 
 sort of action to a wooden one ; in fact, were there as much 
 " work," and of a similar character to that in a wood ship, an iron 
 one would hardly keep afloat a single hour. Prom this a little 
 consideration would have shown that he was anticipating an evil 
 which does not and could not exist, and even if it did, or could, 
 the mode invented by Mr. Daft would prove a complete antidote. 
 
 Mr. Grantham, who patented and advocates the building of a 
 double wooden ship, or casing, one of four inches, and another of 
 two inches thick all over the hull of an iron ship, at the moderate 
 cost of £4000 for wood and labour, not including the copper, 
 which wooden ship or casing has only to carry the copper sheath- 
 ing, goes into some minute calculations to show how infinitesimal 
 is the action sideways of the motion or working of the ship, on the 
 strakes of an iron hull to cause them to open or give by the motion 
 of the ship; and proves, apparently to his satisfaction and the 
 advantage of his system, that this motion is inappreciable. 
 
 Now, when an engineer or practical man advances an opinion 
 (especially where it is a decided or unqualified one) for or against 
 any new invention which has not been tested in actual work, and 
 consequently is in the position of not having any practical proof 
 for or against it, it becomes his duty to give some reasonable and 
 practical proof that he has good grounds for his opinion, and show 
 to such as can understand that he is not in error, nor biassed by 
 interested motives, and therefore capable of giving a fair opinion on 
 the subject ; there are two reasons why this should be done — first, 
 to show that he understands the subject on which he dogmatises ; 
 and next, to prevent doing undeserved damage or injury, when a 
 difference of circumstances would have produced a change in the 
 course of procedure. 
 
 No doubt it may be objected by many who have not taken the 
 trouble carefully to investigate and understand this plan of con- 
 struction, that it cannot be as strong, or even so good as the 
 ordinary " in-and-out lap " and the old " butt " system, and that 
 because wood caulking is employed it must therefore be all that 
 the worse. 
 
 It will be a difficult matter to convince any sensible person that 
 planing, or chipping and filing the butt ends of the plates in each 
 strake, fitting them neatly together, riveting up, and then caulking 
 them, can in any way strengthen the ship, or be superior to keep- 
 ing them the thickness of the plate apart, caulking them all round 
 if desired, and filling them up with dried compressed teak. It is 
 utterly impossible to make a strong job of an ordinary, butt, and 
 all the caulking in the world does not mend the matter ; in fact, 
 rather the contrary, as it throws a strain tending to cause the butts 
 to open, for there is no cohesion between the ends ; in fact, for all 
 
110 THE FOULING AND CORROSION 
 
 the good that is done by the caulking, the interstice might just as 
 well be smeared over with butter. 
 
 The only valid reason for perpetuating such a faulty and unsatis-; 
 factory mode of construction, must be that which we always have 
 advanced in favour of perpetuating evils, viz., that "it always was so,^' 
 or " we have always done so •" such absurdities not being blessed 
 with a single satisfactory or practical reason for their continuance 
 which could convince any one with the least scientific knowledge 
 that they are either right or ought to be continued. 
 
 Mr. Daft's mode of construction may be likened to, and embodies 
 the principle so well put forth and advocated by Mr. Barnaby, Assis- 
 tant Constructor of the Navy, in his excellent paper on "Economy 
 of Material in Iron Decks and Stringers," read before the " Insti- 
 tution of Naval Architects " in 1866, namely, that of " cutting out 
 portions'' to make the rest stronger. That this is the case he 
 fully proves, and it was admitted to be so by the Chief Constructor 
 of the Navy, Mr. Reed, in the discussion which ensued. 
 
 It has been objected that the wood caulking is not sufficient, and 
 would not be strong enough; but it is evidently forgotten by those 
 who raise this objection, that if wood is a material strong enough 
 to construct a ship of, and oakum or worn-out rope strong enough 
 to caulk it with, that dried compressed teak expanded by the 
 moisture and its expansion further increased by the nails holding 
 the zinc must be tenfold stronger, and, moreover, not likely to work 
 loose, or be afiFected by the water as oakum is. One great advan- 
 tage of Mr. Daft's plan is, that by the use of a proper tool each 
 seam, or edge of each plate, can be caulked as is usual with the 
 lapped seams in iron ships, and the teak caulking applied after, thus 
 making security doubly secure, and avoiding the use of " butts," the 
 weakest and most objectionable portions of the hull of an iron ship. 
 
 Experience has proved that teak moderately dry, and without 
 any further preparation, when driven into iron grooves and exposed 
 to moisture, holds with great tenacity — in this case rectangular 
 grooves are meant, but they may even be two or three degrees 
 bell-mouthed or opened outwards, and yet the teak will hold in 
 firmly under considerable strain. No under-cutting or dovetail 
 is required under any circumstances whatever, but to set at rest all 
 doubts on the subject, the grooves may be dovetailed by simply 
 shearing the plates at an angle, and these grooves may be filled in 
 solid with teak as the work proceeds, or they may be filled in with 
 three strips, two bevelled to suit the grooves, and square on the 
 other side to receive the third piece, namely, a tongue of teak to 
 tighten all firmly in, and this kind of filling may be done with 
 marine glue, or the ship may be plated and riveted, and the grooves 
 filled in with solid pieces of compressed teak, and marine glue may 
 be used if desired. 
 
OF IKON SHIPS. Ill 
 
 Teak possesses this important advantage over oak when used 
 about iron ships — that it has no acid in its composition to attack 
 the metal. The injury done by this acid to iron bolts^ when used 
 in oak-built shipsj is well known^ whilst teak, possessing as it does 
 an oily nature, seems fitted to act as a preservative to the iron of 
 the hull, and for this reason it is always used by iron shipbuilders. 
 
 The great firmness with which dried and compressed wood 
 maintains its position when expanded by the moisture of the 
 atmosphere is well known ; an excellent example of this will be 
 found in the celebrated compressed trenails and keys used for 
 railway purposes which have been so long successfully manufac- 
 tured by Messrs. Ransome and May. Another example is the 
 plan of splitting out granite in the quarries by means of dried 
 wooden wedges, which when driven in are either wetted or left 
 exposed to the dew and damp, the result being the sure and 
 speedy detachment of the desired block. An American has also 
 applied the same principle to fixing in the handles of tools, first 
 making them thoroughly dry, then compressing them and driving 
 them into the socket ; and these are never known to become loose. 
 
 One objection the author has had most persistently urged by 
 one or two individuals against this system of construction is, that 
 by keeping the plates apart at the edges or butts a great amount 
 of strength to resist a compressive strain is lost, and that therefore 
 any plan of construction by which the power of resisting strains is 
 diminished must be at once condemned and rejected as useless. 
 It will be interesting here to examine this view of the case, and 
 see how far theory and practice agree, from which operation we 
 shall arrive at something like a common-sense view of the case. 
 
 Ships are generally built to stand a strain of twenty tons per 
 square inch of section in tension, and twelve tons on the same 
 sectional area in compression. Now, as the greatest amount of 
 strain at the butts, namely, the tensional, which tries to pull them 
 apart, is provided for, and resisted by, the double row of rivets on 
 each side of the joint, it follows that the rivets only, receive and 
 resist the strain, and this strain be it remembered, is received on 
 one half of the circumference of the rivets only. In the case of 
 the lesser amount or compressive strain, it is assumed that the 
 two ends of the plates being in contact increases the power of 
 resisting compression, because this strain tends to bring them into 
 contact, and that they assist the rivets in doing their work. A 
 few moments' investigation of this theory will at once prove its 
 fallacy, and show to any thinking practical man that such objec- 
 tions are utterly valueless and untenable. Now, as the compres- 
 sive strain at the butts is received by the rivets precisely as the 
 tensional strain, only the direction being towards the joint instead 
 oi from it as in tension, and being received on one half of the 
 
112 THE FOULING AND CORROSION 
 
 circumference of the rivets only, it follows that the rivets do the 
 work, and, whether the hutts touch or are separated, can make no 
 difference, seeing that these same rivets in tension had withstood 
 twenty tons per inch of section, the strain being received on the 
 opposite half of the circumference; therefore, unless it can be 
 proved that one side of the rivet will stand a strain of twenty tons 
 better than the other side will stand a strain of twelve tons, this 
 objection must be at once rejected. 
 
 There can be no doubt, however, that the plates will not be so 
 rigid in compression, or so well able to encounter that strain 
 without yielding or buckling, as they would that of tension ; but 
 assuming that they are sufficiently rigid when put together to 
 transmit the strain of twelve tons to the rivets at the butts, then 
 as these rivets can stand the strain of twenty tons it will be ex- 
 tremely difficult to show that they are less capable of withstanding 
 that of twelve tons, or that any appreciable advantage is gained by 
 bringing the butts into contact. It may be possible that in the 
 case of very bad riveting something might be gained by so doing, 
 but then when tension took place no advantage would or could be 
 gained by it. No plan which can be urged in support of bad 
 workmanship should be countenanced for one moment, and least 
 of all in the case of a matter of such vital importance as the con- 
 struction of iron ships. 
 
 Taking the case of f " plates 3 feet wide, riveted with open butt 
 joints according to Lloyd's rules, the space between two horizontal 
 butt straps will be 28". In this 28" there are 15 rivets oii each 
 side of a vertical joint ; each rivet is "6", and therefore the total 
 area of rivets is 15 x '6" = 9 square inches. Taking the shearing 
 strength at 20 tons per square inch of section, the ultimate strain 
 which the rivets wiU bear is 180 tons, either in compression or ex- 
 tension of the joint. 
 
 In the case of a solid plate where there is no vertical joint, the 
 area is 28" x j" = 21 square inches. The ultimate strength to 
 compression being 12 tons per square inch, 21 x 12 = 252 is the 
 ultimate strength of the plate in compression. The strength of an 
 open butt joint to a solid plate is therefore as 180 to 252, or as 
 1 to 1-4. 
 
 This is exactly the proportion of strength of a close butt joint 
 compared with a solid plate in extension ; but the addition of the 
 horizontal butt strap to the open butt joints gives a greater 
 increase of strength to resist the compressive and tensile strain in 
 the direction of the length of the ship, amounting to 7^ per cent, 
 of the total sectional area. This is a clear gain in tensile strength. 
 
 Assuming that a "close" (?) butt is equal to a solid plate, this 
 apparent objection is easily overcome by increasing the vertical 
 butt straps so much as to take another row of rivets, the next 
 
OF IKON SHIPS. 113 
 
 being 8 in number, then we get 8 x "6" = 4-8 x 20 = 96 tons, 
 making with 180 a total of 276 tons for a treble-riveted butt, 
 against 252 tons for a solid plate, the extra weight of a third row 
 of rivets being about 25 lbs. for each vertical joint. This is 
 allowing that an ordinary " close " butt is equal to a solid plate, 
 which, however, is never the case. If even a perfectly straight 
 line at right angles vertically and horizontally could be accom- 
 plished, and if a perfect butt joint could be made — neither of 
 which conditions can ever by any possibility exist — then even a 
 butt joint would be weaker than a solid plate. 
 
 A common close vertical butt would, under a certain pressure 
 from the inside or the outside of the skin of the vessel, allow of 
 the breaking of the strap much sooner than an open butt; the 
 latter permits of the strap bending, and the possibility of its 
 righting itself again, but in the former case the strap is broken 
 short in two. 
 
 Looking at the bow and stern of a ship, and taking her as 
 running stem-on to or right against a vertical rock, it is not 
 difficult to see that her lines — circular on plan — render every 
 vertical joint liable to open outwards, and the straps to be broken 
 short in two, as last described. 
 
 It is a fact that a butt joint, though most carefully made and 
 without regard to expense, is always found to require caulking, 
 which after all can only be done superficially, and is soon depre- 
 ciated by wear; and as there is no plan yet discovered of 
 " shrinking together " a butt joint, or increasing its stability and 
 firmness by caulking, it remains with metal to metal no firmer or 
 faster together than if placed simply to touch without pressure. 
 
 Assuming, for the sake of argument, that an open butt is weaker 
 than a " closed" (?) one, and that an extra row of rivets cannot be 
 added to the vertical butts, what does it amount to ? Simply that 
 there would be the vertical butts from the garboard strake to the 
 load water-line. All above may be carried out on the plan of the 
 orthodox butts; and if such a contingency occurred as running 
 end-on to vertical rocks, it must, in all such cases, be the deck- 
 line, or thereabouts, of the vessel which has to sustain or give way 
 under the shock ; therefore open butts below the water-line could 
 not affect the case. 
 
 Further, how much of "butt-joint" work is affected by this 
 system below the water-line? Taking a 1000 to 1500-ton ship 
 (builders' measurement), and taking the platies at 10 or 11 ft. long, 
 and the strakes at 3 ft. wide, we have from 370 to 450 vertical 
 butts, according to the length of the plates up to the load water- 
 line (of 20 ft.) ; so that from this it will be quite clear that the ship 
 would find, at least, as much resistance to breaking her back on this 
 principle as on any other- 
 
 8 
 
114 
 
 THE FOULING AND CORROSION 
 
 Another great advantage peculiar to this system^ in case of 
 repairs or removing a plate, is, that with the open butt, and fair and 
 flush plan of construction, the plating can be removed plate by 
 plate, without disturbing or having to fit against any of the sur- 
 rounding plates, each plate being distinct and separate from all 
 the others ; but notwithstanding this fact, the whole are combined 
 as a complete skin by the butt straps. 
 
 Taking an ordinary butt joint to be as strong as a solid plate, 
 we have through a butt joint in two strakes 2' x 36" x |"= 54 □", 
 then 54 x 12 (12 tons for compression of wrought iron) =648. Two 
 plates occupy 5' 3", vertical section f.%^= 123-4 tons per foot of 
 vertical section, as usually built. 
 
 
 
 
 
 
 
 
 Fig. 4. 
 
 
 
 
 
 
 
 
 
 
 A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 B 
 
 
 On this system, assuming the line a b, fig. 4, to be the point of 
 failure, we have 4 solid plates and 5 butt strakes in compression, 
 and the shearing of 15 -J" rivets. 
 
 4x 36"x |"=108 a" C 145i x 12 = 1746"" 
 
 180 
 
 '= 37^ 
 15x6=9x20= 
 
 = ' 45.6 = 128-4 tons. 
 
 Daft's system being stronger than the old system as 128-4 tons are 
 to 133-4 tons. 
 
 Mr. Daft, in the year 1866, read the following paper on "The 
 Jointing of Plates in Iron Shipbuilding," before the Institution of 
 Naval Architects, which goes so fully into the question that, by 
 his permission, the author has printed it in extenso, as follows : 
 
 " The jointing of plates in iron shipbuilding admits of consider- 
 able improvement, which may be made at little or no cost. 
 
 " It is the practice now to make what is termed a " lap" joint 
 longitudinally, or running fore and aft; and another kind of joint. 
 
OF IRON SHIPS. 115 
 
 called a "butt," vertically, or running in broken lines from the 
 keel upwards. Why there should be two kinds of joints would not 
 appear clear to a casual observer ; but on consideration it becomes 
 evident, and it is — because lap joints are inadmissible, vertically, 
 on account of the detrimental effect that such joints would have 
 upon the speed of the vessel, and not, that I am aware of, on any 
 other account. 
 
 " Butt joints are not used fore and aft, with very few exceptions 
 (as in the wales of large ships), because of the great expense of 
 making them and of their extreme liability to get out of order. It 
 will be clearly seen, therefore, that butts are used vertically, be- 
 cause in that situation laps are unsuitable ; and it is also clear that 
 laps are used horizontally, because perfect and durable butts in 
 that situation are impracticable. 
 
 " That lap joints would always be used where butts are now, if 
 not prohibited by the loss of speed they would occasion, scarcely 
 admits of a doubt ; for the inherent inferiority of a butt, as com- 
 pared with a lap, is manifest to every one practically acquainted 
 with the different modes of caulking laps and butts respectively. 
 And here let it be distinctly understood that in this paper no blame 
 is intended to be laid upon builders of iron vessels for not making 
 butt joints that will stand the straining of a vessel in a storm with- 
 out opening : it is simply impossible to do so. 
 
 " The principle of butts interdicts the practicability of perfect 
 joints. Nevertheless credit is due to all who have laboured to- 
 wards making that which in the nature of things could not be 
 arrived at, namely, a sound and durable butt joint in the skin of 
 a ship. As near an approximation thereto as possible has been 
 made in all cases of good workmanship. Notwithstanding which 
 it is the opinion of the author that the butt joints of iron vessels 
 have been the sole cause of many fatal disasters. 
 
 ''Let us analyse a butt joint, and, for the sake of argument, 
 admit that the edges have been planed and fitted absolutely water- 
 tight {see A, fig. 5) ; in other words, that the two edges of the plates 
 touched metal to metal throughout their surfaces, and that there 
 was no disturbance of the parts when the riveting was done, and 
 therefore that the caulking on the surface was done for fashion's 
 sake, as it could not be needed if the joint was perfect without it; 
 however, assuming an absolutely perfect joint, what is to keep it 
 perfect in a gale ? In a storm, an iron vessel opens as many mouths 
 as there are butts. 
 
 " Again, let it be remarked that it is not the workmanship that 
 can fairly be blamed ; it is the principle that is at fault. *And if 
 the application of a principle, selected expressly for costly produc- 
 tion, deceptive appearance, and calamitous effects, had been in- 
 tended, it could scarcely have excelled that which is involved in 
 
116 
 
 THE FOULING AND CORROSION 
 
 the butt joint of an iron ship. The vessel labours, the butts open, 
 the water enters, and the ship goes down, and all because it is 
 physically impossible to caulk a butt like a lap at the bottom of 
 the joints (cc). Whether the 'President' went to the bottom 
 from this cause is a question never now to be answered; nor 
 whether yawning butts did not give the finishing stroke to the 
 ' London/ 
 
 Fig. 5. 
 
 L 
 
 poo o o 
 O I o o o o i o 
 
 @@ 
 
 @ @ 
 
 @ @! 
 @ @1 
 
 ,®^@, 
 
 J 
 
 _) 
 
 A. — Shows a common butt joint. 
 
 B. — TTie ordinary lap. 
 
 c c. — The bottom or root of the butt joint. 
 
 D. — Shows the effect produced upon a butt joint when the sides of 
 a vessel are bulged outwards. 
 
 B. — The opposite effect, as when the sides are driven inwards. 
 
 p. — The new joint under pressure from the outside. The laps 
 forming this joint are caulked as usual at the roots, and would con- 
 sequently be tight under such a strain. 
 
 G. — Shows a strain from the inside with the new joint. The 
 adhesion by reason of good caulking would probably keep this joint 
 good. 
 
 H. — The new laps with parallel edges filled in with compressed 
 teak, making a fair flush surface and a perfectly water-tight joint, 
 irrespective of other caulking. 
 
 K. — A joint which is stronger than the solid plate, both in tension 
 and compression. 
 
OF IRON SHIPS, 117 
 
 " It -will be seen that with the most perfect butt that it is possible 
 to makcj there is no provision whatever for shrinking together and 
 holding the joint good and close against a strain ; the mere con- 
 tact of the plates is all that can be accomplished, and, that done 
 well, the superficial caulking which it afterward receives does not 
 improve it. Let the vessel labour in a sea-way, and then, at the 
 very moment when all her joints are wanted, if possible, tighter 
 and firmer, the butts open and let in the water. 
 
 " In short, there are inherent evils in butts, and they ought to 
 be abolished in favour of laps, even at the expense of speed, if it 
 be necessary; for where so many lives are constantly in jeopardy, 
 speed ought to be a secondary consideration. ' Slow and sure' 
 would be a better motto at sea than ' fast and dangerous.' Yet 
 there is no necessity to lose speed by abolishing butts in favour of 
 the laps ; they may be adopted even for vertical joints with no loss 
 of speed or strength whatever ; on the contrary, with advantage in 
 every respect. Before introducing laps for butts, let us ask why 
 (if butts are stronger than laps, as some persons assert) are they 
 not used invariably fore and aft, in order that "when a vessel takes 
 the ground, and thumps her keel on a hard bottom (which happens 
 as often as running stem-on to a vertical rock), she may have the 
 benefit of such joints to support her? In such a case, it is con- 
 venient to think that laps are strong enough. 
 
 "Why not confess at once the truth; namely, that well-made 
 and well-caulked laps are stronger than butts, because it is a 
 physical impossibility to make a perfect butt, and, moreover, if it 
 were possible to make it, it would nevertheless be impossible for it 
 to remain tight at sea throughout a gale of wind. At the same 
 time it would be as well to admit that, but for the loss of speed, 
 laps {see b, fig. 5) would be greatly preferable for vertical joints, 
 on account of the simple and effectual manner in which they can 
 be made perfectly water .^ight, and because they will remain so 
 under extraordinary strains. 
 
 " Let us look at it in a new light. We should be glad of butts 
 fore and aft, if they could be made as easily as laps, and would 
 remain water-tight, because they would give us a flush surface and 
 an increased speed. On the other hand, we should be glad of laps 
 vertically, if we could get a flush joint. Now, it is not difficult to 
 have the advantages of laps as well as of butts ; the advantages of 
 both, without the common inevitable disadvantages hitherto attend- 
 ing them. The plan is to adhere to laps throughout the plating, 
 but to bring the edges of the plates so near together that, having 
 caulked them as laps and made them perfectly water-tight, you 
 then additionally caulk the seams with a suitable material, such as 
 dried and compressed teak, hammered tightly into the grooves. 
 Thus you make a second perfectly water-tight caulking of a nature 
 
118 THE FOULING AND CORROSION 
 
 that will swell under the divers strains to which a ship is exposed, 
 and offer more obstruction to the entrance of the water under try- 
 ing circumstances than any metal to metal joint. In addition to 
 this extra and superior caulking, there is the important advantage 
 gained of a flush surface all over the hull of the vessel. 
 
 " With regard to the supposed strength of a butt over a lap, we 
 have the following facts to guide us {see k, fig. 5) : — Take a butt 
 joint of a 3-feet strake, f inch thick, and consider it equal to a 
 solid plate, then we have 36 inches x f inch x 12 tons (the 
 ultimate strength of wrought iron in compression) = 334 tons. 
 Take a lap joint as proposed, and shown at h, fig. 5, and we have 
 20 rivets, then 20 x "6 x 20 (the shearing strength of rivets) = 
 240 tons, and the compressive strength of the longitudinal strap 
 10 inches x f inch x 12 tons = 90, making 330 tons for the 
 strength of new laps against 824 tons for that of the old butts, 
 even considering the latter as perfect as a solid plate. 
 
 " Well may Mr. Grantham say, as he does in his work ' On Iron 
 as a Material for Shipbuilding,'' ' that the lapped joint appears to 
 be preferable to the flush (butt) joint, and it is probable that if the 
 former principle had invariably been adhered to, much trouble and 
 expense would have been saved, as the flush plating (butt joint) 
 seems to have originated in a mistaken idea that it increased the 
 strength and improved the appearance of the ship.'' Nothing, 
 certainly, can be more fallacious than to imagine that a butt joint 
 increases the strength of the ship. By a proper system of riveting, 
 the lap joint may always be made stronger than a butt, even 
 though the latter be considered equal to a solid plate : a considera- 
 tion which the author, an old boiler hand, never pays to a butt 
 joint. What a butt loses in strength by want of caulking at c c, 
 the root of the joint, is not taken into account in favour of laps 
 versus butts. It must, however, be something worth having, in the 
 item of adhesion. 
 
 " As to the facility of producing moderately regular grooves in 
 the plating, by close lapping, it is only necessary to mention, what 
 would in all probability occur to any practical iron shipbuilder, in 
 the process of plating, that a strip or gauge of iron the thickness 
 of the plating and a few inches wide, in fact, a strip of the plating 
 itself, which is always at hand, is put in between the edges of the 
 plates, while they are being fitted and marked for punching ; and 
 that if put there while the riveting is done, a moderately uniform 
 groove is left on the removal of the gauge, depending more or less 
 as to the correctness of the edges of the plates. If they have been 
 planed they will be more easily caulked, as lap joints, and will 
 receive the teak with greater freedom than if left from the shears ; 
 but if left from the shears, and irregular on their edges, the only 
 extra trouble or expense is that of baulking, as would be the case 
 
OF IRON SHIPS. 119 
 
 with laps under similar circumstances. The teak is easily made to 
 fit any irregularity of groove without the slightest difiiculty, and is 
 hammered tightly in and pared off flushj leaving a more seaworthy 
 joint than can otherwise be accomplished. 
 
 " There are many ways of compressing teak and timber generally, 
 but it may be well to say a few words upon teak, per se, before we 
 apply it. Teak, or tectona grandis, is of the natural order verbe- 
 nacese — a native of Burmah; and is abundantly met with from 
 Ceylon to the Moluccas. In Europe, it appears of modern applica- 
 tion to shipbuilding, but seems destined to supplant oak where 
 stout timber is needed in iron shipbuilding. Its use for boats in 
 its native country appears of considerable antiquity, and probably 
 the aborigines of those parts where it is indigenous had learned by 
 experience that it did not corrode iron. However, we know that 
 oak does destroy iron in consequence of the gallic acid it contains, 
 and we have found that teak is free, or sufficiently so, from that 
 acid, and therefore produces no injurious effect upon iron when in 
 contact with it in sea-water. But teak has another and important 
 advantage over oak : it is, that while oak fails with a compressive 
 strain of 10,000 lbs. per square inch, teak will bear 12,000 lbs., 
 and may be looked upon as very nearly half as strong as wrought 
 iron in compression. 
 
 '' By comparing the structure of teak in various sections under 
 a powerful microscope, with corresponding sections of oak, it is not 
 difficult to see a marked superiority in favour of teak for solidity 
 and compactness of structure. It will bear compressing when dry 
 to the extent of 0"25 of its thickness without injury to the fibre. 
 It has been subjected to this reduction of thickness, and afterwards 
 immersed in water, when it has invariably returned to its normal 
 thickness; thus it appears a very suitable wood for filling iron 
 grooves in a ship^s skin. 
 
 " There are many ways, as I have said, of compressing teak : it 
 will be sufficient to mention one which answers very well. Assum- 
 ing a -f- inch groove has to be filled, a teak plank -| inch, or bare 
 inch thick, is passed through a pair of rolls set to f inch, full, and 
 the compression is at once effected. To reduce it into strips, a set 
 of six or eight saws of small diameters are mounted upon one 
 spindle, with washers between the saws keeping the saws an inch 
 apart. Running the compressed plank through these saws, cuts it 
 at one operation into strips 1 inch x -f- inch. No mistake can 
 then be made even by the most unintelligent workman as to the 
 way the teak is to go into the grooves; he will hammer it in the 
 way it fits, and which is the way that it will swell by moisture 
 until it is very difficult to remove it ; the excess of flush teak is 
 pared away by a plane and chisel in the simplest possible manner. 
 
 " Before the three years' experience now had with teak caulking. 
 
120 THE FOULING AND CORROSION 
 
 and before the great number of experiments which have been made 
 with it, one felt inclined to dovetail the groove, which was easily 
 done by shearing the plates at a certain angle, and, as the plating 
 of the vessel proceeds, knock in from the open ends of the grooves 
 the dried and compressed strips of teak, cut in sections to suit the 
 dovetail ; but experience has shown that teak, tightly driven into 
 a rectangular groove, becomes a firm fixture, and is diflBeult to 
 chip out. In fact, a groove may with perfect safety be two or 
 three degrees ' bell-mouthed,' or opened outwards, and still retain 
 teak with an immense hold when it has been tightly driven in. In 
 case the teak be used as a medium for sheathing, every nail which 
 is driven in tends to increase its hold by compressing the teak. 
 If a piece of teak be fitted loosely into a groove, so that it may be 
 removed by the .fingers, after a nail has been driven into it, con- 
 siderable force is required to draw it out. 
 
 "Butts may, therefore, be safely abolished in all cases and 
 situations in favour of laps, and all laps can be made fair and 
 flush as butt joints, the full advantages of both being thus attained 
 by one and the same plan." 
 
 Mr. Mackrow, naval architect, observed that " The longitudinal 
 strap is really only the usual inner strake narrowed ; but consider- 
 ing what Mr. Grantham and others have advanced, that the vertical 
 butts should be planed so as to make them tight, this is very much 
 like going to the other extreme ; still I believe there can be no 
 practical objection ; and I think Mr. Daft is entitled to have the 
 opinion of practical men as to whether the system is likely to be 
 adopted with regard to sheathing. It certainly adds a little to 
 the weight. I have worked it out, and find that in a 1000 ton ship 
 — of course the system need only be carried to the load line — and 
 assuming that to be about fifteen feet, it would add about twelve 
 tons to the weight of the ship. The extra lap, therefore, would 
 add about 2^ per cent, to the gross weight of iron in the ship. If 
 the vessel be made as he proposes, with the grooves, and the zinc 
 answers the purpose, and there is every reason to believe from 
 certain experiments that have been made that it does answer the 
 purpose to which he intends it to be applied, then there may be a 
 saving effected in the thickness of the plates ; therefore the excess 
 by the introduction of the extra lap may be compensated for in 
 that way, because the thickness of the plates on the outside may 
 be reduced. If there is no real objection to this system, and it 
 appears to me thoroughly good at every point, certainly the intro- 
 duction of the piece of teak round the centre, sides, and ends of the 
 plates, will form an admirable method for nailing on whatever 
 sheathing you please. I had some plates riveted together, and the 
 teak put in in this way, and I had the satisfaction of nailing firmly 
 into it. If we had rather a large surface of plate, say thirty-six 
 
or IRON SHIPS. 131 
 
 feetj and we had to partially drill the plate to attach the centre, 
 there might be some objection; but otherwise I think there can be 
 none. Mr. Daft read a paper last year, but I do not think the 
 merits of it have been fully seen or understood. I am sorry to 
 make such a remark here, but I want you to see its practicability. 
 I believe experiments are being tried at Portsmouth by the Govern- 
 ment. They are not yet completed, but have been going on for 
 nearly twelve months, to test the value of zinc in immediate con- 
 tact with iron, whether, in the galvanic action set up, the excoria- 
 tion of the zinc becomes equal to copper. Mr. Grantham has had 
 his plan before the public for many years ; I do not know whether 
 it has ever been adopted. The expense of coating Her Majesty's 
 large vessels upon that plan would be very great, whereas the 
 expense here is very little. Ships of 3000 tons have been built 
 flush merely to obtain speed.^^ 
 
 Mr. John Grantham remarked, " I will just say one word with 
 regard to the general principle of applying soft materials for the 
 joints of iron ships. I would say, as a rule, it is undesirable, and 
 I regret exceedingly that I cannot say or feel anything more favor- 
 able about it. I believe one great feature in the strength of our 
 iron ships is, that they are iron and iron ; that there is no inter- 
 mediate material of any description interposed. "We began by 
 placing soft materials in the joints of ships, but we very soon 
 abandoned it. It is a very old thing to try to make tight joints in 
 iron ships by putting soft materials between them, but we found 
 that there is nothing like iron and iron. I do, therefore, feel at the 
 very outset that Mr. Daft^s plan is not such as to commend itself 
 for practice. Then with regard to the sheathing which, I suppose, 
 was the real origin of this plan, I fear that that also will not be 
 found to answer the purpose, simply because copper, and even zinc 
 plates, require to be attached very frequently. The nails by which 
 they are attached must be very close together, and therefore it 
 will not be practicable, I think, to secure it merely round the edges 
 of the plates of the hull, as the nails must thus necessarily be too 
 wide apart. I would not say much upon this point, because I have 
 a plan, as the world knows, of my own ; but on the question of the 
 joints I have a very decided opinion that it is undesirable to inter- 
 pose anything of a softer nature than the iron itself." 
 
 Mr. Allen remarked, " I think one word may be said upon that 
 point, that the object of introducing wood between the body of the 
 joint is not to make the joint, it is merely to fill up the space. 
 The joint is made by the caulking of the iron sheathing; you have 
 iron and if on. I am not advocating the plan, but I think it is a 
 distinction that ought to be fairly drawn ; the wood is not inter- 
 posed to make the joint, but to make up the surface." 
 
 Mr. Daft, in his reply, well observed, " Mr. Grantham appears 
 
132 THE FOULING AND CORROSION 
 
 to imagine that the teak caulking -which is put in between the 
 edges of the plates has something to do with the strength. Now, 
 I do not think Mr. Grantham believes so. It is a lap joint, and 
 it must be evident to every gentleman here, who understands what 
 a lap joint is, and who understands the mechanical difference be- 
 tween a lap joint and a butt joint, that I am only using lap joints, 
 and that the caulking has nothing to do with the strerigth. I 
 think I tried last year to make Mr. Grantham understand that, 
 and if I failed to make Mr. Grantham understand that then, that 
 it is only a lap joint, and that the caulking has nothing whatever 
 to do with the strength of the ship, I am afraid I never shall be 
 able to make him understand it. Although teak is very strong, 
 yet I would not depend upon it, because I am mechanic enough 
 to know that to depend upon teak for strength in the skin of an 
 iron ship would be ridiculous. But if you put laps, which surely 
 are as strong when they come near together as when they are far 
 apart, what is the difference between the straps which I use and the 
 inside strake but the width ? I say, when you bring the edges of 
 your plates together to make common hutts, you weaken the con- 
 struction of your ship, and you pretend to make a joint. Mr. 
 Grantham says the joints ought to be planed, and so does Mr. 
 Fairbairn, and they speak very strongly on that head. If I had 
 butt joints, and watched them every one made, and had them, if 
 possible, watertight, so that the light should not be seen through 
 them before they were put together, I should know that the 
 moment the rivets were put in the joints would be broken, and 
 that there would never afterwards, without caulking on the sur- 
 face, be a watertight joint, and when you have caulked it on the 
 surface, you have made it a delusion ; you have made it appear 
 a perfect joint, but it will open upon the slightest strain. It 
 does open, and no man that we have ever heard of has found a 
 plan of drawing it together and making it watertight. Therefore, 
 I say, it is a snare, for we are led to believe that it is a perfect 
 joint, when it is not so. I do not care what sheathing you put — 
 put the best; but if we separate the butt-joints (which are a 
 mockery, a delusion, and a snare) so that you can get to the root 
 of the joint and caulk them, then I say, and every man who knows 
 anything of the construction of a ship will say, that a lap joint is 
 a much better joint than a butt joint, and that it will stand far 
 better. It is not right to assume that any strength will be had 
 from the teak; but caulk a lap, and you get a good deal of 
 strength by adhesion. It is another question as to how much 
 strength you can get by this adhesion. Make your butt as per- 
 fect as you can ; spend i£5 upon every butt in your ship ; and I 
 will give any mechanic in the world £5, after they are riveted, for 
 every water-tight joint. It cannot be, gentlemen — emphatically I 
 
OF IRON SHIPS. 123 
 
 say it cannot be — it is a deception. Therefore, what you all well 
 know, a lap joint is the best to adopt for caulking. Put any- 
 thing else in if you like, but I think teak is the best thing; if you 
 can press it you give it a tendency to expand when it receives 
 moisture, and therefore you get a good hold. You do not depend 
 upon the teak at all for strength ; you have got a stronger ship 
 before you put the teak in, and it is none the worse for having the 
 teak. It is a less expensive mode by 50 per cent, than any I have 
 heard of yet; I am prepared at anytime to prove that. It de- 
 parts less from the general construction of the ship than any other 
 plan. It brings the work closer together; it does not give you a 
 greater midship section; it does not give you a second ship to 
 build ; but it is all done while you are plating — it is not more 
 costly in that_ respect. Mr. Mackrow has calculated — and he is 
 very near the mark — that the extra material in a 1000-ton ship is 
 twelve tons. It is really ten tons of material that is added; you 
 can tell better than I can what that will cost. But is it an easier 
 mode of building ? You can set men to work at it with a great deal 
 more freedom than you can with any other plan. You give them 
 a strip or gauge to make their grooves by ; they then put one plate 
 against the other, with a strip between, and can mark the holes, 
 have them punched, and it will be better and simpler work alto- 
 gether. There are ten to twelve tons more of material in a 1000- 
 ton ship, and it all goes to strengthen the ship." 
 
 To this it is evident there can be no valid objection ; for, as Mr. 
 Grantham has well said, " a very few additional tons make an 
 almost imperceptible diiference in the draught of water, but mate- 
 rially increase the strength and durability of the ship." 
 
 The knowledge that zinc, when placed in contact with iron, 
 would prevent the iron from corroding and wasting away, led to 
 the introduction of the system known as " galvanising," by means 
 of which the protective action of the zinc was obtained for the iron 
 by carefully cleaning it, and immersing it in a bath or vessel of 
 molten zinc, when a coating of zinc would adhere to the iron, and 
 thus, so long as any remained, protect it from corrosion. 
 
 This plan has been adopted for a variety of uses, such as sheets 
 for roofing, water-tanks, chains, thimbles, &c., &c. ; but, on the 
 whole,, experience has not proved it to be so valuable as at first 
 expected, nor to be applicable with equal advantage to all the 
 purposes originally contemplated. No doubt this may be owing 
 in some measure to the mode in which the operation is carried 
 out, and the care and attention given to the process. 
 
 Experience shows, however, that the mechanical application of 
 the zinc to the iron required to be protected i_s more likely and 
 certain to give the desired results than the chemical plan of 
 galvanising, at least in the case of sheathing iron ships, and it 
 
134 THE FOULING AND CORROSION 
 
 promises to secure far more important advantages than can be 
 gained by the chemical method. 
 
 By the use of zinc as the sheathing material for iron ships two 
 most important advantages are secured, first the immersed portion 
 of the ship is kept free from dirt ; and the next is that the iron of 
 the hull is kept in the highest degree of preservation, the destruc- 
 tive action of the water on the iron being transferred to the zinc 
 through galvanic action. 
 
 The influence of zinc and iron in contact is so powerful that 
 even if some portion of the iron be exposed, it will not oxidize, by 
 the protection afforded by the galvanic influence of the other por- 
 tion in contact, to those at a distance. In ordinary circumstances 
 the atmosphere does not contain sufiicieut moisture to afford a 
 conducting medium for the electricity generated; and wherever 
 the zinc is removed oxidation will take place, but this will not 
 extend to those parts where the metals are in contact j but vrhere 
 a conducting medium such as water does exist, the zinc affords 
 protection to the iron, even to those parts at a considerable dis- 
 tance from the contact of the metals. 
 
 Zinc as a material for sheathing purposes has these important 
 advantages — it is the cheapest material in, the market ; it can be 
 readily obtained in any qvATititY ; it is easily manufactured; it is 
 perfectly innocuous when applied to iron; does not require to be 
 insulated ; can be cheaply employed ; will endure as long as copper ; 
 and is superior to anything at present known for the purpose. 
 
 Mr. Daft, whilst perfecting his system of construction, considered 
 many ways of fastening the zinc to the iron hull, one of which 
 was turning over the edges of the zinc sheets so that they would 
 overlap the edges of the iron plates and project into the groove, 
 when the teak strips, being driven in between the overlap of the 
 zinc sheets, would expand and keep them in their places without 
 the aid of nails; but such grave objections were seen to exist 
 against this plan, and several others of a similar character, and no 
 appearance of their reliability being found which would justify 
 their use in practice, whilst the superiority of nails for fastening 
 was so apparent, they were at once discarded, and the use of nails 
 adhered to. 
 
 After proving the value of zinc as a sheathing for iron in sea- 
 water, in conjunction with the Government " Special Committee 
 on Iron," in 1863 and 1864, Mr. Daft received instructions from 
 the Lords Commissioners of the Admiralty, dated February 18th, 
 1865, to visit Portsmouth yard in order to see that certain experi- 
 ments with two plates on his plan were satisfactorily made for 
 testing the efficiency of zinc sheathing for iron ships. 
 
 Two plates -I" thick, 7' long, and 3' wide, as shown in the 
 lithograph at page 128, were made up with f" straps at the 
 
' OF IRON SHIPS. 125 
 
 back or insidcj so as to represent the actual plating of a vessel of 
 some 3000 or 4000 tons, and grooves according to Mr. Daft's 
 patent were left 4" wide between the edges of the plates. These 
 grooves were subsequently filled in with teak strips, and the sur- 
 face made fair and flush. The plates were encased in teak frames 
 and backs, made waterproof, so that the plates should have their 
 faces or outsides only exposed as in the case of an actual vessel. 
 
 Two of the plates had the zinc fastened in the centre, as shown 
 by the letters A and B in the lithograph, but the other had no 
 centre fastenings whatever, the zinc being held by the nails round 
 the edges. A represents the fastening, which in this case was a 
 teak plug driven into a hole drilled some depth into the plate, and 
 a zinc nail was driven through the sheathing into the plug. B was 
 an iron screw passing through the zinc sheathing into a hole drilled 
 in the plate, representing the skin of the ship and tapped to receive 
 it. c. c. c. c. c. c. c. c. were iron nails driven into the plugs of teak 
 in the same manner as A. These fastenings were not needed, but 
 from the plate having been covered all over with glue and felt, 
 they were put in to get contact, and also as an experiment. 
 
 On the 31st of March, 1865, these plates were put into the 
 water in Portsmouth Harbour, one at one end of the great landing 
 stage and the other plate at the other end, where they remained 
 during the whole of two summers until August 12th, 1866, when 
 they were drawn up, and examined in the presence of the Lords 
 of the Admiralty, with the results described by the correspondent 
 of the ' Standard ' in the Appendix at the end of this work. 
 
 The original intention was to nail on the zinc sheathing direct 
 against the bare iron, in order that the contact between the zinc 
 and iron should be perfect, and the necessary amount of electro-gal- 
 vanic action should be set up when the plates were lowered into the 
 water, to keep the zinc exfoliating or peeling away at a rate which 
 would keep them clean and bright ; but by an accident the iron 
 was coated all over with a composition much used in Her Majesty's 
 Dockyards called " Hay's glue," and a sheet of tarred felt inter- 
 posed ; consequently, contact had to be established by using the 
 nails with which the sheathing was fastened on, long enough to 
 go through the teak caulking and to turn again on the iron at 
 the back of it. A few iron nails, common clouts, were introduced 
 in order to establish firmer and more enduring contact, and to 
 prove that they might be used, if not to an advantage, certainly 
 without detriment to the work. 
 
 The unfortunate interposition of a substance between the zinc 
 and the iron rendering the former liable but for the feeble action 
 established by the long nails to foul to a certain extent, as in the 
 case where zinc is used for sheathing wooden vessels, was a source 
 of anxiety to Mr. Daft, and was only dispelled when, on the 13th 
 
126 THE FOULING AND CORROSION 
 
 of October, 1865, the plates were raised for preliminary examina- 
 tion. (They were to be kept under water for twelve months as the 
 trial.) At the examination after six months' immersion they were 
 found perfectly clean, though not bright, as would have been the 
 case had the chemical action not been checked by insulation. 
 
 The zinc had not wasted enough. One ounce per square foot 
 per annum, the rate at which it had been disappearing, was not 
 sufficient to ensure a bright surface, a bright surface being that of 
 all others the most to be desired for obtaining speed in iron ships 
 and vessels. This fact, thoroughly established by Mr. Daft pre- 
 viously, induced him to have a third experiment (fig. 6) tried at 
 Portsmouth, and which is fully reported upon further on. At the 
 end of thirteen months a correspondence took place between Mr. 
 Daft and the Admiralty as to raising the two plates, but as summer 
 was again approaching, it was suggested by the Admiralty that 
 they had better remain three months longer, and thus to go through 
 another season, for the rapid growth of weeds and barnacles. 
 This suggestion was readily agreed to by the inventor, and when 
 they were taken up for the inspection of the Lords Commissioners 
 of the Admiralty, consisting of Sir John Pakington the Pirst 
 Lord, Sir John Hay, &c., &c., on the 12th of August, they were 
 found still in perfect cleanliness, though as before not bright. 
 About the frame, and on the iron chains in which the plates were 
 slung, were immense quantities of barnacles and weed, but not a 
 vestige on the plates. 
 
 Mr. Daft then suggested that one or both plates should be 
 stripped, and everything, zinc, nails, teak, iron, fee, thoroughly 
 overhauled, and an accurate account taken of the loss of the 
 zinc J and this was, he believes, with respect to one plate, done 
 accordingly. Not that the " authorities " have furnished him with 
 particulars at present, but, having asked for that favour, he is in 
 hopes of getting them. However, it may be asserted without fear 
 of contradiction, that the zinc had lost only at the rate of one 
 ounce per square foot per annum ; and it would be better to lose 
 double that quantity. 
 
 One ounce per square foot per annum is not much more than zinc 
 sheathing loses on wooden vessels, when a very feeble galvanic 
 action is created — possibly at times none at all — and then fouling 
 more or less occurs. Not that it must be supposed that fouling is 
 peculiar to zinc alone, for other sheathings, copper and yellow 
 metal, as has been shown in former pages, foul to the same extent 
 as iron or zinc, or any other metal where their condition is made 
 negative in an electro-chemical sense. If, for example, contact with 
 iron and copper, or iron and yellow metal, be made in sea-water, 
 then copper and yellow metal will foul rapidly at the expense of the 
 certain destruction of the iron, then made the positive metal. 
 
OF IRON SHIPS. 
 
 137 
 
 Mr. Daft tbinksj in order to wear out the old wooden tubs with 
 as little expense as possible, and yet keep them useful and safe as 
 long as possible, that it would be wise to use iron nails and zinc 
 sheathing — for the zinc would preserve the iron fastenings about the 
 vessels, and the clouts (iron nails) iu the sheathing would hold the 
 zinc, and materially aid in keeping it clean by increasing its exfo- 
 liating qualities. Zinc for wooden ships under this treatment 
 would become equal to copper and yellow metal for cleanliness, 
 would last quite as long, and would cost not more than one third of 
 the price. 
 
 To ensure a thoroughly clean surface the peeling away should 
 
 Fig. 6. 
 
 go on at a rate of not less than two ounces per square foot per 
 annum. At that rate it is kept absolutely bright ; and if it be 
 desired, it can be still further increased to two and a half ounces, 
 by leaving certain parts of the hull unsheathed — for example, the 
 keel, stern, and sternposts. Sec, for by exposing a greater proportion 
 of iron than zinc, within certain limits, the zinc is more rapidly 
 destroyed, whilst, as has been shown in another place, the uncoated 
 iron is, notwithstanding the want of immediate contact with the 
 zinc, kept perfectly free from corrosion or fouling. 
 
 If zinc be used of -jV" thick, as a good stout sheathing fit for a 
 vessel of 3000 to 5000 tons, it would weigb thirty ounces to the 
 square foot j and assuming a loss of two ounces per annum, and 
 
128 THE FOULING AND CORROSION 
 
 that when it was reduced to half its thickness it would want re- 
 sheathing, then there would be at least seven years of a clean and 
 safe bottom, without the slightest anxiety about it in respect of 
 either fouling or corrosion, and no trouble or expense in docking, 
 so long as the ship be kept off the ground and clear of anything 
 likely to damage the sheathing. 
 
 In order that the insulation, which was likely to be obtained by 
 the plates having been covered with " Hay's glue and felt," might 
 not act prejudicially to the invention, Mr. Daft had a third plate 
 (fig. 6) prepared, without any glue or felt on the surface, the metals 
 zinc and iron being put in close contact, so that unimpeded galvanic 
 action and exfoliation of the zinc sheathing might be secured. 
 
 The engraving (fig. 6) shows the form of plate, the teaking, the 
 zinc, and the frame in which the plate was secured for immersion. 
 This plate was put down at the end of 1865. 
 
 Some persons have remarked that zinc fouls, or becomes 
 encrusted with a whitish deposit or oxide, when attached to the 
 hulls of wooden ships, and that, therefore, such a result would be 
 sure to occur if zinc were used on the hulls of iron ships. That 
 zinc does foul on wooden bottoms is a fact ; but that because it 
 does so on wood it must on iron, is not a fact, nor can a single 
 proof be brought forward to show that it would do so. 
 
 The reason of zinc fouling or becoming encrusted when used for 
 sheathing wooden hulls, is because it does not exfoliate with suffi- 
 cient rapidity to produce and maintain a clean surface, it being a 
 less oxidizable material than copper or yellow metal when exposed to 
 the action of salt water. On an iron hull, however, the galvanic 
 action of the iron on the zinc produces just that amount of exfoli- 
 ation necessary to produce and maintain a clean surface, and 
 decreases the durability which, in the case of wooden hulls sheathed 
 with it, is found to be an objection. 
 
 It has been proposed to galvanise or coat with zinc the plates which 
 form the hull of an iron ship ; and the benefits to be derived from 
 such a course have been deemed very great. Now, so long as the 
 zinc lasted on the plates or hull of the ship, no doubt the desired 
 efifect would be produced ; but it does not seem to have occurred to 
 the advocates of this system, that when the whole of the zinc had 
 exfoliated, the ship would be then in the position of an ordinary 
 iron vessel, but with this serious disadvantage, that the plates would 
 be greatly deteriorated by the operation of galvanising, nor do 
 they propose any plan by which the ship could be recoated : perhaps 
 she might be taken to pieces, regalvanised, and put together again ; 
 but anyway, galvanising under such circumstances can only be 
 called a makeshift. 
 
 The great drawbacks of galvanising are that the zinc will peel or 
 flake off; it does not penetrate the pores of the iron, or amalgamate 
 
PLAN AND SECTION OF THE ' 
 
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OF IRON SHIPS. 129 
 
 with it — the operation of coating with the zinc spoils the iron ; it 
 does not last long, but soon peels off; in fact, a moment's re- 
 flection should have shown that, to be of any real utility^ its appli- 
 cation should have been so arranged as to admit of easy renewal or 
 removal when required; and for this purpose sheathing with sheets, 
 in the ordinary way, followed with copper on wooden hulls, would 
 be that most certain to fulfil the requirements of the case. The 
 author has not been able to find any proposal of how a ship was to 
 be regalvanised after the first coating of zinc put on the plates 
 before the ship was built had been worn off, nor does it seem to 
 have entered into the consideration of any of the proposers that 
 this process would require to be repeated. 
 
 Mr. Mallet has remarked of galvanising that " in sea water it is 
 entirely useless, and as applied to iron ships it would be absolutely 
 hurtful, because, independent of any ill effects upon the toughness 
 of the iron, one of the effects of any partial removal of the thin 
 surface coating of zinc is that a thin coating of carbonate of lime 
 is rapidly deposited upon that which remains, and upon that 
 excessively thin bed of lime, fouling takes place immediately; 
 plants and animals readily attach themselves to it." 
 
 The late Mr. Appold remarked, at the Institution of Naval 
 Architects, in 1861, that "the portion of the 'Great Eastern' 
 which gave the most trouble was a portion near the rudder which 
 was galvanised. It was corroded all over by the action of the salt- 
 water." 
 
 Mr. C. Lungley, iron shipbuilder, immediately stated that 
 "whenever we want iron to do what we call work, we do not 
 galvanise it, but if it is merely wanted to be kept clean, then we 
 do. By galvanising the iron you open the pores of the metal, and 
 the tensional strength is lessened." 
 
 Zinc has been proposed and used as material for the construc- 
 tion of ships in place of iron. Some years ago (1852) M. Guibert, 
 a shipbuilder and owner at Nantes, built a sloop of this material, 
 which, it is said, answered so well that he built a steamer of 300 
 tons register also of zinc. Numerous barges and lighters are 
 made of this material, and have been in use for many years on the 
 continent. It is claimed for zinc, that a vessel of it will hold out 
 over iron the advantages of more space with an equal bulk, greater 
 buoyancy, and incalculable durability. 
 
 It will be interesting to examine the claims of zinc as a material 
 to be used in competition with iron for building ships, and com- 
 pare the results of the investigation. 
 
 To tear a piece of zinc with a sectional area of one square inch 
 requires a force of 16,000 lbs., which will give a safe working strain 
 of about If tons as the amount not to be exceeded. 
 
 Taking a similar section of boiler plate, we find 22 tons as the 
 
 9 
 
130 THE FOULING AND CORROSION 
 
 limit, whidi will give at a similar ratio about 5| tons as the safe 
 working strain.. From this we get the fact, that zinc is a trifle over 
 one third of the strength of iron ; but taking it as only one half, it 
 would follow that an iron ship of given dimensions built of |" 
 plates would require, to possess equal strength, to be made of 
 plates of zinc 1" thick. 
 
 As to weight, a plate of iron J" thick weighs 30 lbs. per square 
 foot, whilst a plate of zinc 1" thick weighs 37^ lbs. per square 
 foot ; therefore the idea of getting equal strength with less weight, 
 or greater buoyancy with equal strength in the same dimensions, 
 is clearly a mistake, and it would seem to show that, except under 
 very exceptional conditions, zinc is not a useful or economical 
 material to be employed for this purpose, especially as we must 
 bear in mind the difference of cost between zinc and iron. Added 
 to this is the hitherto unknown, and it may almost be said " im- 
 possible," point, of how this material is to be put together in a 
 manner at once simple, workmanlike, and with sufficient strength 
 to enable a ship to be both seaworthy, safe, and cheaply and 
 readily constructed. 
 
 The advantages of zinc as a sheathing material for iron ships 
 are far beyond that of any material at present known ; and though 
 many fondly believe that copper or yellow metal can be used for 
 this purpose, increasing experience and general knowledge will in- 
 contestably prove the impossibility of so doing, and the great risk 
 of injury to the unfortunate vessel to which it may be applied ; 
 whilst zinc will daily rise in estimation, and prove itself the only 
 metal which can be used for the purpose; 
 
 Zinc preserves iron in sea-water. It entirely prevents the rust 
 or decay of the iron so long as any particle of it remains in 
 metallic contact with the iron. The zinc is kept perfectly clean 
 by a feeble galvanic action exfoliating or peeling it away. This 
 action is caused by metallic contact with the iron ; thus, ix}. nailing 
 on the zinc sheathing the zinc nails (where such are used) may all 
 touch the iron, so that any sudden sweep about the hull is covered 
 without difiBculty. 
 
 Zinc is about one third the price of copper or yellow metal, is 
 of less specific gravity, does not rank higher than iron in the 
 galvanic list, whilst both copper and yellow metal do, and with 
 due precaution as to the respective surfaces exposed of zinc and 
 iron, the zinc may be made to last longer than copper or yellow 
 metal, and keep clean all the time ; therefore sheathing with zinc 
 can be done at one third of the cost of copper or yellow metal, 
 other expenses being the same in each case. 
 
 Wherever the zinc sheathing on a wooden ship touches the 
 copper, yellow metal, or iron fastenings of the vessel, the galvanic 
 action, aided by the working of the ship's hull, is the cause of a 
 
OF IRON SHIPS. 131 
 
 hole being quickly formed ; the chafe of the water soon extends 
 the fissure, and the result is that the sheets soon come off. From 
 this it has been inferred and stoutly maintained by many, that a 
 similar result must follow when zinc sheets are applied to iron 
 hulls. 
 
 That such a result would follow in the case of an iron ship does 
 not appear at all probable, inasmuch as the cause of it in a wooden 
 ship would here be wanting. In a wooden vessel the galvanic 
 action caused by the other metals, copper, iron, or yellow metal, is 
 concentrated on a very small surface of the zinc, and there is 
 besides this the constant working and motion of the planks and 
 fastenings, and, as a necessary consequence, the continued fric- 
 tional and galvanic action produce a small hole ; but as the iron 
 ship does not work as the wooden one, and has the surface of iron 
 evenly exposed to the zinc, throughout the whole surface coated 
 or sheathed with it, it is evident that concentrated and frictional 
 action on any definite spot cannot arise or exist. 
 
 In order to sheathe ships already built, and assuming the plating 
 to be " in-and-out" lap, as is now generally the case, a modification 
 of the " Dafting" system may be carried out as follows : — Take 
 teak boards of a thickness equal to the plates, and fill in the 
 spaces formed by the inside strakes, so as to make a flush surface. 
 The boards may run fore and aft, or they may be placed with 
 their lengths at right angles with the keel ; or they may be a com- 
 bination of both ways, as may best suit the lines of the vessel, and 
 require the least number of fastenings. 
 
 The fastenings should be screws, as shown in the accompanying 
 engraving (Fig. 7). The inside strake being drilled about two 
 
 thirds through, and tapped to suit in position and pitch two holes 
 near the ends of each board ; these, i. e. four screws to each board, 
 would be sufficient to firmly hold it, if put athwartships, as its 
 length would seldom exceed three feet, and would oftener be two 
 feet six inches. If the boards shape better when placed fore and 
 aft, then they may be used as long as convenient, and have a 
 greater number of screws accordingly. The holes in the plates 
 should be filled with tallow before the screws are put in, in order 
 that they will easily draw when the teak should want renewing. 
 
133 THE rOtJLING AND CORROSION 
 
 With a strake of teak and a strake of iron alternately, there will 
 he no diificulty in sheathing such a hull. 
 
 Let the sheets of zinc just or harely cover in width the teak 
 strakes of all the sheathing for those strakes ; let the sheets to 
 cover the iron strakes cover an excess in width of an inch or there- 
 abouts on each side of them, and lap over, or over and under the 
 teak sheathing, in order that rows of nails may be driven through 
 the laps, and into and through the teak, and turn again upon the 
 iron. The best nails for this purpose are common iron clouts. 
 The zinc preserves them; they do not injure the zinc; they are 
 tough and strong ; and being well selected for length, they make 
 superior work of the sheathing. 
 
 The serious drawbacks to this modification of " Dafting" are 
 the drilling of the skin of the ship, and the possibility of the worm 
 destroying the teak boards. Both these objections are entirely 
 avoided by the system of narrow grooves, where no drilling is re- 
 quired, and where the strips of compressed teak are so thickly 
 studded with nails as to defy the ravages of the teredo. The ex- 
 periments at Portsmouth have abundantly proved this, for during 
 sixteen months of immersion, the teak frame about the plates was 
 much eaten away, yet the teredo had not made the slightest mark 
 upon the imprisoned teak, nor had it apparently suffered the 
 faintest decay. 
 
 This system of protecting existing ships was submitted by Mr. 
 Daft to the Admiralty in a letter at the commencement of the year 
 1866. 
 
 One thing is evident, and that is, that our costly iron-clads at 
 present constructed should have every precaution taken to pre- 
 serve the hulls and armour-plating from decay and injury ; and al- 
 though the plan just described is far from perfect , or anything like 
 so good a job as could be made if the hull were "Dafted," or spe- 
 cially built in accordance with Mr. Daft's invention, so as to be 
 sheathed on his plan, still the advantages to be gained, and the 
 certem^y with which they must result, at an.jva.te. without injury 
 to the iron of the hull, will sooner or later ensure a fair trial of 
 this system, in spite of prejudice and indifference ; and it must be 
 admitted that even though it would not be so workmanlike a job 
 as if the ship had been specially built for the purpose, still the cer- 
 tainty with which fouling and corrosion would be prevented render 
 it worthy of adoption. 
 
 As it always happens that the most ignorant persons are the 
 most prejudiced and dogmatical, most difficult to convince, and 
 always desirous of having statements corroborated, it may inteirest 
 such to read the opinions of the following well-known gentlemen, 
 whose knowledge is seldom questioned, and whose capabilities in 
 giving opinions are generally fully admitted. 
 
OF IRON SHIPS. 133 
 
 No doubt a little patient study of the subject, with a desire to 
 clearly understand the conditions involved and the results arising 
 from galvanic action^ will do much to enlighten us ; still it is im- 
 peratively needful that the study should be undertaken without 
 reference to preconceived ideas or generally received opinions, if 
 anything like conviction and a thorough comprehension of the 
 subject be desired. 
 
 AH ideas of poisoning, the non-existence of the subtile action 
 known as galvanic, and the unimportance of it if not largely deve- 
 loped, should be given up, and the matter should be studied with 
 care and attention, and an earnest and painstaking desire to find 
 out the truth. 
 
 Professor Faraday wrote in 1845, in his report to the Harbours 
 of Refuge Commissioners, " It has often struck me that the cast- 
 iron piles proposed for lighthouses or beacons might be protected 
 by zinc in the same manner as Davy proposed to protect copper 
 by iron." 
 
 Dr. Kane says, " Zinc preserves the other metals, even if it be 
 iron, from oxidation." 
 
 Gmelin, in his ' Handbook of Chemistry,^ states that " Zinc 
 completely protects iron from sea water;" and this is exactly 
 proved by the experiments and tests carried out by Mr. Daft and 
 the Government. 
 
 Dr. Percy explained at th& Royal United Service Institution the 
 action of the zinc sheathing in keeping clean thus : — "The zinc is 
 perpetually dissolving away, so that the hold of these animals is 
 prevented. In the course of time the whole of the zinc disappears, 
 so you see here corrosion plays a very important part." 
 
 Professor Rankine (Institution of Naval Architects, 1865) has 
 remarked that " there can be no doubt that zinc galvanically pro- 
 tects iron, and also that it is, comparatively speaking, a durable 
 material in sea water; but then comes the question of the adhe- 
 sion of shell-fish and weeds. If it can be established by experi- 
 ment that the galvanic contact between the zinc and the iron 
 causes the zinc to behave in the way that copper sheathing does — 
 to oxidize and scale off, and carry away the barnacles or other ad- 
 hering bodies with it — then surely that presents a solution of the 
 problem, provided you can find a practicable way of attaching the 
 zinc to the iron." 
 
 Professor Thomas Graham, of the London University, has ob- 
 served that " the effect of zinc in protecting iron from oxidation 
 has been known to chemists for some time. When these two 
 metals are in contact, an electric or galvanic relation is established 
 between them, by which the iron ceases to be susceptible of corro- 
 .sion by dilute acids, saline solutions, or atmospheric humidity," 
 
 Professor W. T. Brande, F.R.S., of the Royal Mint, observed 
 
134 THE rOULlNG AND CORROSION 
 
 that " in this way an arrangement susceptible of electric excitation 
 is obtained, in which, consistently with the laws of electro-chemi- 
 cal action, a preservative power is conferred by the zinc upon the 
 other metal; for in all cases in which two different metals are in 
 contact, a current of electricity may be established in them in 
 such a direction as to protect the least oxidizable of the two metals. 
 In the case before us the respective metals are iron and zinc — the 
 iron is the protected metal, and the zinc the protector ; and con- 
 sequently, when these combinations are subjected to the action of 
 water and other agents, the iron is preserved from corrosion so 
 long as any zinc remains to maintain the electric current." 
 
 Professor Grace Calvert stated, in a communication to the So- 
 ciety of Arts, that in 1858 he and Mr. R. Johnson " took plates of 
 iron, and covered one surface with -^, -^f -jVj and -j-^ of its extent 
 of zinc plate, which we tied close to the iron plates, and then im- 
 mersed them in soft and sea water. We examined these plates at 
 the end of one, two, and three months, and finding that the zinc 
 had exercised a very remarkable preservative efifect upon the iron, 
 we brought the matter under the notice of Mr. Robinson, ship- 
 builder, Newcastle, who promised to institute a series of experi- 
 ments in connection with his iron ships, to ascertain whether the 
 results we had obtained in my laboratory would be confirmed in a 
 practical sense; but this gentleman soon after fell ill, and ulti- 
 mately died." 
 
 These results left, says the Professor, " no doubt of the great 
 protective power exercised by zinc against the corrosive action of 
 sea-water upon iron plates;" but the conclusions he draws from 
 these results as to the best method of practically applying the zinc 
 are certainly wrong, and are known by practical men to be highly 
 objectionable. He says : " I therefore think that all iron used in 
 shipbuilding should be galvanised; and as this operation is now 
 performed with such facility and so little expense, I cannot see 
 any commercial objection to its general adoption." 
 
 Mr. John Bourne, in the 'Artizan' of 1844, wrote as follows 
 respecting zinc preventing corrosion in iron ships : " With this 
 view, the plates of the bottom should, we think, be zinked within 
 and without. If the paint were rubbed off, the zinc would still 
 preserve the iron ; and if both paint and zinc were rubbed off the 
 outside, the iron would still be shielded from corrosion by the 
 galvanic influence of the zinc inside, the bilge-water being suffi- 
 cient, or capable of being made sufficient to complete the galvanic 
 circuit. To carry out this idea, it would merely be necessary to 
 build the ship with zinked plates instead of unzinked plates, not to 
 zinc the hull after it has been completed. It would not be neces- 
 sary to zinc the rivets, as their proximity to the zinked surface 
 would be an effectual protection." 
 
OF IRON SHIPS; 135 
 
 From the discussion on Mr. Mackie's paper on '' Sheathing Iron 
 Ships/' read at the British Association in August, 1866 (an ab- 
 stract of which is given in the Appendix) , we learn that Admiral 
 Sir Edward Belcher said he " was perfectly sure that it must be 
 successful." 
 
 Professor Rankine stated that in his judgment the " invention 
 was a most valuable onCj and supplied a want that was, perhaps, 
 felt more severely than an^ other. By getting rid of the out 
 seams, it did get rid of a certain amount of skin resistance." He 
 also regretted that " so important and excellent an invention had 
 not before this time been brought into practical use." 
 
 Mr. Galloway said that there had been " no more important 
 subject than this brought before the sections of this Association." 
 He hailed with " great pleasure and satisfaction the plan now pro- 
 posed, as the best plan hitherto discovered of effecting the desired 
 object." 
 
 Dr. Fairbairn, C.B., F.E.S., said it " would certainly prevent the 
 growth of anything of the kind (barnacles, weeds, &c.) on the 
 ship, and be a perfect success." 
 
 Mr. Abel, Admiralty Chemist at Woolwich, said the prevention 
 of fouling " was no doubt achieved by this invention." 
 
 The President, Mr. T. Hawksley, C.E., said " it was impossible 
 to overrate the importance of this excellent invention." 
 
 Captain H. F. M'Killop, R.N., says — " The partial success ob- 
 tained with paints or compositions will not bear comparison with 
 the success to be obtained by the use of zinc, which will very soon 
 supersede all anti-fouling compounds." 
 
 Admiral E. P. Halsted remarks — "I have full confidence that 
 zinc sheathing is destined to give to iron ships cleaner bottoms 
 than ever were bottoms before." 
 
 It will be desirable here to make some remarks on the expan- 
 sion and contraction of the zinc sheathing, and the iron of the hull 
 to which it is attached. Zinc from 32° to 212° expands -0029 of 
 its length; wrought iron expands under the same circumstances 
 •0012, giving a diiference of "0017, which, multiplied by 36, the 
 number of inches in a yard, = "0612 in that length. Thus, it will 
 be seen that zinc expands 3 parts in 1000, over a range from 32° 
 to 212°=-i% in 100, or f" in 10 feet nearly. If we deduct the ex- 
 pansion of the iron, and take 45° as the maximum difference of 
 temperature, we have -^' in 3 feet as the greatest that can happen, 
 which amount will be entirely lost in practice in the slack of the 
 nail-holes. 
 
 In order to test this point, sheets of zinc 7 feet long were nailed 
 upon iron plates in March, 1865, and put under water in Ports- 
 mouth harbour. They were taken up in six months, and found 
 perfectly flat and safe, without the slightest appearance of bulging 
 
136 THE FOULING AND CORROSION 
 
 or having bulged. Wood may be said not to shrink endwise, but 
 it does shrink crosswise. With this irregularity of actioiij it re- 
 tains sheathing of zinc, copper, or yellow metal, without causing 
 material irregularity. On iron zinc lies very much flatter than on 
 wood, and is assisted in keeping so by the regular expansion and 
 contraction of the iron in sympathy with the zinc. The difference 
 of expansion between the zinc and iron is infinitesimal, and not to 
 be discovered in practice. 
 
 The following estimate of the saving in a sailing ship of 1000 tons, 
 constructed and sheathed upon Mr. Daft's improved plan, by having 
 no fouling or docking, has been made by a gentleman in the north 
 of England, who has had large experience in shipping as owner : 
 
 30 men, including captain and mate . 
 
 Food about £96, say 
 
 Wear and tear of ship .• . 
 
 Percentage of cargo : this takes a cargo worth 
 j620,000 ; that amount would at home pay in- 
 terest at 5 per cent. = 1000, -Vth, being, say . 
 
 J433 
 Add to this cost of docking and painting, loss of time in dock. 
 For a steamer add monthly consumption. Working expenses of a 
 1200-ton ship=jg600 per month, or say £500 per month for a 
 1000-ton ship. 
 
 1000 tons . . £500 
 500 
 
 £ 
 
 s. 
 
 d. 
 
 200 
 
 
 
 
 
 100 
 
 
 
 
 
 50 
 
 
 
 
 
 83 
 
 
 
 
 
 £1000 Saving per month . £433 
 Docking and painting 150 
 
 cc 
 
 Total per annum if kept clean for one year . . £583 
 
 The advantages gained by this principle of construction are — 
 1st. More rapid and cheaper construction, because there are no 
 butt" joints to be planed or chipped and fitted, and conse- 
 quently no difiBcult caulking or imperfect joints. AH the plates 
 may be taken as they come from the shears, doing away with all ac- 
 curate fitting; and as all the joints are alike and perfectly simple 
 to make, more rapid and cheaper construction are thereby ensured. 
 2nd. A more uniform and secure mode of caulking, because all 
 the joints being lap joints they admit of more effective caulking 
 than " butts," so that by means of suitable tools the laps at the 
 bottom of the grooves can be caulked perfectly water-tight. This 
 is easily done by giving a slight bend to the caulking tool when 
 necessary. 
 
OF IRON SHIPS. 137 
 
 3rd. A fair flush surface all over the hull, which is secured by 
 hammering strips of dried compressed teak into the grooves^ which, 
 in consequence of the expansion caused by the absorption of 
 moisture, causes these strips to have and maintain an immense 
 hold. This is further increased by the sheathing nails, which, 
 when driven in, cause them to expand and hold tighter. 
 
 4th. A good foundation for nailing on the sheathing, obtained in 
 an excellent manner by the compressed teak, whereby an iron ship 
 can be sheathed with the same facility as a wooden one. 
 
 5th. A hull perfectly free from fouling is secured by applying a 
 metal sheathing which avoids all danger of this annoyance. By 
 the use of zinc the feeble galvanic action caused by metallic contact 
 with the skin of the ship is entirely in favour of the iron ; and by 
 slightly increasing the exfoliation of the zinc its valuable qualities 
 as a sheathing are much improved, and for iron ships it is superior 
 to any other metal, and is the only one which can be used without 
 causing injury to the iron of the hull. 
 
 6th. A stronger and safer vessel. A vessel built on this plan is 
 stronger than the ordinary lap-jointed, or even a butt-jointed 
 vessel. A lap-jointed vessel has been known to shear off her rivets 
 on taking the ground, and there is always a danger of this happen- 
 ing in common lap-jointed vessels, whether single or double 
 riveted, when they strike on a hard bottom. 
 
 By this system the laps are brought so close together that, in 
 the case of a strain upon the rivets, as just described, it would be 
 impossible to shear them oflp by reason of the edges of the plates 
 touching each other before the rivets could be cut through. 
 
 The strength of the ship is still further increased by the caulk- 
 ing of a very hard and durable wood, viz., teak, dried and com- 
 pressed and driven into the grooves, which acts as a buffer in case 
 of accident between every edge of a plate and its neighbour, thus 
 reducing the danger of damaging the hull of the vessel from a 
 shock ; for under the momentary pressure there will be in the teak 
 itself a very considerable resistance to compression in addition to 
 the hold of the rivets. 
 
 A fair flush surface for the hull of a ship would be universally 
 preferred were it not for the dif&culty of making in the usual way 
 perfect and durable horizontal " butts j" but here the filling of the 
 grooves with dried and compressed teak, and paring it off fair with 
 the iron, the hull is made perfectly water-tight irrespective of 
 ordinary caulking. 
 
 By this system all the joints, both longitudinally between strake 
 and strake and vertically between the ends of the plates, are formed 
 by riveting to butt straps on the inside. 
 
 The edges of the plates do not touch, but a space is left between 
 them equal to the thickness of the plates. 
 
138 THE FOULING AND CORROSION 
 
 Thus grooves are formed extending round each plate, and into 
 these grooves strips of dried and compressed teak are driven form- 
 ing a flush surface, and giving a firm foundation to which the 
 sheathing is nailed. 
 
 Zinc sheathing and zinc nails are used. The sheets of zinc are 
 made in size to suit the iron plates, and the nails are of a suflBcient 
 length to reach the iron skin of the ship and turn over at the point 
 on touching the iron. 
 
 The nails thus driven, and the tendency of the teak to expand 
 by moisture, secure the strips most effectually in the grooves. 
 
 The sheathing is laid immediately on the ship's skin, and being 
 of a substantial thickness (in proportion to the durability required) 
 it lies perfectly flat without other hold than that given by the nails 
 round the edges. 
 
 If, however, it be thought desirable to have other fastenings, 
 holes may be drilled partly through the iron, and plugs and nails 
 used. 
 
 The galvanic action between the zinc and the iron is essential 
 for the double purpose of preserving the iron and peeling away the 
 zinc. 
 
 The action is precisely the reverse of that which occurs if copper 
 or yellow metal be used as a sheathing, in which case the copper 
 is preserved and fouls, and the iron, which is then the positive 
 metal, is destroyed. Hence the importance of using zinc, irrespec- 
 tive of its being only about one third the price of copper or yellow 
 metal, in order to make iron the negative and the protected metal. 
 
 There can be no doubt that this plan removes one point on 
 which the opponents of iron ships have long taken their stand, and 
 fulfils the wish "that no such objection as liability to fouling may 
 remain as a handle for those who oppose the employment of iron 
 as a material for shipbuilding." 
 
 This plan is cheap and simple, it requires no felt, no paper, no 
 wood, no " composition," no drilling, no tapping, no insulation, 
 but actual metallic contact; thus satisfactorily proving that the 
 simplest plan is, as usual, the best, and most suited to meet the 
 requirements of the shipowner and shipbuilder. 
 
 The successful action of this system, founded as it is on the un- 
 erring laws of nature, with the extra speed, the immense saving of 
 time, the prevention of corrosion, and increased durability attained 
 thereby, the abolition of frequent docking, its heavy expenses and 
 loss of time, must make it a boon to all iron shipowners, and a 
 most valuable and important adjunct to the maintenance of our 
 naval superiority. 
 
 The advantages to be gained by constructing and using iron 
 ships, which will remain free from fouling as long as a coppered 
 wooden one, with the plating almost indefinitely preserved, and 
 
OF IKON SHIPS. 139 
 
 the hulls possessing fair flush surfaces, are so ohvious, so importantj 
 and have been so long sought for, that there is no longer any 
 reason, now that all are attained by Mr. Daft's invention, why 
 these advantages may not be forthwith and fully realised. 
 
 The employment of the " Dafting " system will enable iron to 
 be used for the construction of yachts, for which, up to the present 
 time, it has been found to possess serious objections ; and these 
 have been of greater moment than its other unequivocal advan- 
 tages. In fact, it has been said that if the nuisances of fouling and 
 corrosion of the hulls of iron ships could be got over, there will be 
 no limit to the use of iron, or the purposes to which it wiU be 
 applied in ocean navigation. 
 
 The large ships used in the India and China trade which, from 
 their fouling and corroding so quickly, if made of iron, it is 
 now preferred to construct of wood, may by the use of this system 
 be built of iron, thus securing the known and important advantages 
 of this valuable material, and avoiding its hitherto serious and fatal 
 drawbacks. 
 
 There can be no question but that this plan of Mr. Daft's will 
 remove the greatest objections now affecting the progress of iron 
 ships, to the great benefit of the Government, the iron trade, and 
 the merchant service of this country. 
 
 Whatever theoretical objections or disinclination to apply this 
 system may exist, it is nevertheless beyond a doubt that the power 
 first using iron ships constructed and sheathed on this plan, will 
 possess an enormous advantage, both for offence and defence ; and 
 by its use a small fleet will be quite as well able to do good service 
 as a large one, even though it be more powerful if it be unprovided 
 with the advantages given by this system. 
 
 The importance and advantage of being able to keep the sea, 
 even under sail, with a clean bottom and undiminished rate of 
 speed, seems at present to be of little moment ; and that it is pre- 
 ferred to " find out,'' by contrasting inefficiency with efficiency, 
 the advantages which it would have been wiser to have shown, 
 especially where it concerns a matter of such vital importance. 
 
 It has been well and truly remarked, and it does not seem that 
 it can admit of a question, that " Wherever the services of a ship 
 of war are required, it is indispensable that the ship appointed 
 for this duty should be in all respects efficient; the detention 
 of a ship for some necessary repairs may be a national calamity ; 
 its inferiority as a ship of war may be attended with national 
 dishonour." 
 
 It has been asked, " After all that has been said and done by 
 our great naval architects and builders to perfect iron vessels, what 
 is the use of them if they cannot overtake a copper-bottomed 
 enemy ? And this would be impossible if an iron bottom, without 
 
140 THE I'OULING AND CORROSION OF IRON SHIPS. 
 
 steatliing had been many months at sea, however fast she might be 
 at first." 
 
 The inconvenience, waste, and extravagance attending the carry- 
 ing to sea, as stores, of paints, compositions, &c., are well known 
 to owners, commanders, and officers of iron ships; and all of these 
 may be avoided with many far more serious evils, and a great 
 saving effected by the employment of Mr. Daft^s simple and certain 
 mode of constructing and sheathing iron vessels. 
 
 It has been truly said that "when men's minds are preoccupied 
 by long cherished systems, contrivances, or modes of operation, 
 every effort to dispel error and to introduce improvement is attended 
 with supreme difficulty. The progress of the most practical truth 
 is slow, although to obstruct that progress there may be no artifi- 
 cial obstacles." 
 
 In conclusion, it may be remarked, without fear of contradiction, 
 that the preservation of the hulls of iron men-of-war, and merchant 
 ships, and their maintenance in a state of constant cleanliness and 
 freedom from fouling, are points which are of vital importance to 
 the government, the taxpayers, the shipowners, and the sailors of 
 Great Britain, and all other parts of the civilised world ; and it 
 must be said in the words of Dr. Latham, that " It is by your own 
 eyes, and by your own ears, and your own minds, and (I may add) 
 by your own hearts, that you must observe, and learn, and profit ; 
 I can only point to the objects and say little else than ' see here, 
 and see there.' " 
 
APPENDIX. 
 
 The following pages contain some articles on the prevention of 
 fouling and corrosion in iron ships, which question the ' Standard ' 
 took up in a scientific and thorough manner ; an abridgment of 
 a paper at the British Association ; the report of the result of the 
 Portsmouth trials . of sixteen months' duration ; the remarks of 
 one of the engineering papers on the principle of Mr. Daft's in- 
 vention; a paper read by Mr. S. J. Mackie at the Society of Arts, 
 the latest results of Fouling, and the progress of Improved Con- 
 struction. 
 
 OUR NATIONAL DEFENCES. 
 
 CORKOSION OF lEON SHIPS. 
 
 [From the Standard, August \Oth, 1866.) 
 " In the conduct of every portion alike of our military and naval 
 departments, during the past few years at least, there would appear 
 to have prevailed either a very culpable negligence and want of 
 foresight, or a gross ignorance of what science had discovered or 
 had indicated. Not only have huge plated ships been built upon 
 unproven principles, and on models against the experiences of all 
 the nations who have been engaged in modern warfare, but although 
 such ships are four times as costly per gun carried as our ancient 
 boasted hearts of oak, no properly considered effort has been made 
 to preserve them from that natural corrosion and decay which is 
 the inevitable fate of all iron ships. What the amount of that 
 corrosion has been, so far as the navy is concerned, we have no 
 published means of knowing, although it is well understood to be 
 a very serious item, and one which would astonish the British 
 public if some patriotic member of the House of Commons would 
 move for and get the absolute returns laid before Parliament. 
 Merchant shipowners do not like to tell the cost at which they 
 maintain their vessels ; the late Government has so far been too 
 adverse to letting the verity leak out, or too apathetic about the 
 
142 APPENDIX, 
 
 matter, or too ignorant of the real extent of the evils j while iron 
 shipbuilders do not complain, because they get the repairs, and 
 everybody knows that tinkering is more profitable than building. 
 Thus it is that no one at this moment is possessed of reliable in- 
 formation upon this very important subject. 
 
 " But whatever the extent of our knowledge, whatever the 
 amount of past ignorance and apathy, patriotic men of all parties 
 will agree that in respect to the costly ships we do possess, and in 
 respect also to those large additions to our fleets which are 
 imperatively demanded for the security of the country, an earnest 
 and due consideration should be given to all the means possessed 
 and all the reasonable means proposed for preserving our iron- 
 clads and our iron ships as far as possible from the destructive in- 
 fluences of the chemical and galvanic action of sea-water, as well 
 as from the expensive waste of coal, and the dangerous diminution 
 of speed caused by the fouling of steam- vessels through the growth 
 of marine vegetable and animal organisms upon their hulls. 
 
 " Two topics are thus involved in this national problem — 
 Whether the corrosion of iron ships can be prevented or diminished 
 by any process ? and whether the bottoms of such ships can be 
 kept free from such vegetable and animal growths during long and 
 continuous voyages ? These questions ought long to have been 
 solved; and with the resources which a Grovernment always possesses 
 of getting the best instruction and advice, the blame of any 
 omission cannot be cast off from themselves by our rulers. With- 
 out doubt many difficulties have had to be encountered, many 
 costly experiences bought, but by results alone are governments, 
 like individuals, adjudged; and as not one of her Majesty's ships 
 has up to this moment any efficient protection either from corro- 
 sion or from fouling, it becomes a matter of citizen duty, before 
 the keels of our new ships are laid down, to draw attention to the 
 subject, not doubting the present heads of the Admiralty will give 
 every reasonable proposition careful and just entertainment. Our 
 ancient wooden ships were protected by copper sheathing, and the 
 numerous vessels we yet possess of that class are still so defended ; 
 but what can be done with wood cannot be done with iron. The 
 copper sheathing can be nailed to the wood whilst it cannot be 
 nailed to the iron. This, however, is not the most serious diffi- 
 culty, and at least one effectual plan of construction has been 
 brought before the Institute of Naval Architects which permits the 
 attachment of protecting plates of metal with greater certainty 
 and tenacity than is possible even in ships of the hardest oak. 
 The most terrific obstacle has been so far the intense and rapid 
 decomposition of the iron skin of the ship by the galvanic action 
 of the copper and sea water. In fact, the coppering of an iron 
 ship converts the whole machine into a gigantic galvanic battery. 
 
APPENDIX. 143 
 
 in whicli the iron being the weakest element sufiFers in consequence 
 the greatest amount of destruction. 
 
 " Even a copper penny, it is said, getting into the bilge- water, 
 has in a short space of time corroded a deep and dangerous cavity. 
 The French have attempted, in a bungling way, to get over the 
 difficulty by coating some of their iron ships with planking, and 
 then nailing copper sheathing to this wood coating. Any way, 
 this is building two ships — an outer one to take care of an inner 
 one — and includes an expensive principle which ought never to be 
 tolerated while there exists a possibility of obtaining any direct 
 protection for the iron; and that such a direct protection of the 
 iron is not beyond the possibilities of science we are convinced, if, 
 indeed, it be not already discovered. On these points, however, 
 the absence of sufficiently fall and distinct information prevents 
 
 ~ us from dwelling/ with decision, and we therefore prefer to state 
 some popular facts, and to throw out some suggestive reflections, 
 rather than to submit any precise plans for dealing with these 
 difiBculties. 
 
 ''That corrosion does take place to a large extent, the many 
 cases roughly recorded by the newspapers are sufficient evidence ; 
 
 * and, indeed, so great at one time was considered the evil, that the 
 Adniiralty, in 1847, contemplated the total disuse of iron, and ac- 
 tually commenced the sale of the iron ships then in the navy. 
 They were changed in this determination, it is said, by the favor- 
 able results of a composition proposed by the Government chemist, 
 but more probably were deterred from carrying out the abandon- 
 ment from the impossibility of meeting the requirements of modern 
 naval engines of offence and defence with any other material than 
 the strong and solid metal. No one ncfw would attempt the con- 
 struction of war ships in any other material, and therefore, wasted 
 or not wasted, iron must be used ; but taking into consideration 
 that while the wooden sailing men-of-war, which formerly consti- 
 tuted our proper navy, cost 1000^., and wooden screw ships 2000^. 
 per gun carried, the new rams are costing 4200Z. per gun ; and we 
 may thus be satisfied of the desirability, if not the necessity, of 
 doing our utmost to preserve such expensive vessels by every con- 
 ceivable means from deterioration. 
 
 " That any application of paint, composition, or adhesive coating 
 will never be thoroughly effectual may be well understood by every 
 one who will reflect with due knowledge upon the circumstances 
 under which organic fouling and galvanic corrosion take place; 
 and the same conclusion may be arrived at by inductive reasoning 
 from any plain narration of facts. Taking a few well-known in- 
 stances will be ample to make seen the general conditions of fouling 
 and corrosion. We have, then, the ' Grappler,' in three years 
 from the date of her order for building, corroded with holes up to 
 
144 APPENDIX. 
 
 five inches in diameter ; the ' Jackal/ coated with red lead in the 
 May of one year, obliged to be docked in the April following, her 
 bottom not only fouled with barnacles and weeds, but the plates 
 and rivets corroded to such an extent as to make it necessary to 
 remove upwards of 300 rivets, and to drill holes in the plates, and 
 plug up the most cankered places. The ' Antelope,' on her return 
 from the African coast, fifteen months from her dispatch, had more 
 than six tons of barnacles and parasites removed from her hull, 
 and had also corroded plates and defective rivets. The ' Harpy,' 
 after four years' service on the American coast, was thickly co- 
 vered with shell-fish and weeds. The ' Resistance,' docked a 
 twelvemonth ago to be cleaned, had no less than twelve inches of 
 grass in many parts, although she had been hogged within a month. 
 Another vessel, docked last year, may be given as a further ex- 
 ample that what was an evil in 1847 still continued so; and fur- 
 ther illustration could be appended, if required, to show that the 
 evil remains undiminished to the present time. The ' Royal Oak,' 
 docked in the January of last year, was found to be ' foul beyond 
 all conception ; immense quantities of zoophytes, weeds, and coral- 
 lines flourished in the wildest profusion, and so hard had the little 
 insects formed their habitations, that nothing short of a general 
 scraping with short scrapers would remove the incrustations — the 
 result of six months' accumulation.' 
 
 " Such examples could be multiplied by the column ; but what 
 we have given are suflS.cient for our purpose. Moreover, attention 
 has been frequently drawn to this state of things by ofiBcers of the 
 naval and merchant services alike. It is not, therefore, to prove 
 a case known to exist, but to illustrate the causes and conditions 
 of the fouling and the corrosion, that we have made the selection, 
 believing that when once the causes of any defect or injury can be 
 clearly ascertained the remedies will very quickly be forthcoming. 
 If any further proof of the utter incapacity of paints, varnishes, 
 glazings, or other mere material coatings to grapple with these 
 mischiefs be required, those who desire it have only to search over 
 the nearly 300 unadopted patents which have been registered as 
 preventatives. 
 
 " Taking first the question of fouling, it becomes evident that 
 the proper protection of an iron ship must be a metallic coating, 
 with a constantly clean and self-freeing surface. This no paint, 
 composition, or even mere metallic or vitreous enamel will ever 
 efi'ect. But why this particular surface is absolutely essential be- 
 comes prominent in view of the manner and circumstances under 
 which marine parasitic life and vegetation have their origins. In 
 the case of animals such as cirrhipeds, balani, oysters, serpulse, 
 corallines, and teridines, the young only enjoy a free state, the 
 young only are possessed of locomotion, hence the adhesion of 
 
APPENDIX. 145 
 
 living organisms takes place during their earliest condition as fry, 
 andj therefore, so long as there is any permanent surface for these 
 minute beings to get a footing on for their future growth and de- 
 velopment, so long will some of the myriads which swarm in the 
 sea be at hand ready to take advantage of every uncovered speck. 
 The same with the minute spores of sea-weeds — these only ever 
 attach themselves. Neither do such organisms or such sea-weeds 
 derive the slightest amount of nourishment from the substance to 
 which they are attached. Barnacles and sea- weeds are simply ad- 
 herent, and whilst it is known to naturalists beyond all question 
 that no nutriment is absorbed by either living shelled parasites or 
 by vegetable algse from the objects to which they are attached, it 
 is very doubtful (except in the case of saturated wood upon boring 
 worms) how far any noxious qualities of the material itself is in- 
 jurious to the young fry when they first settle upon it; still more 
 remote is the possibility of injury from such a source to either 
 weeds or parasites when they have attained any considerable ad- 
 vance of age. For this reason alone it will be seen that the most 
 effectual antidote to the settlement or development of any vege- 
 table or animal growth upon the hull of a ship is the maintenance 
 of a perpetually clean and renewed surface — such as would be pre- 
 sented under the condition of a continuous dissolution or a con- 
 tinuous flaking, by which the molecules of metal to which the 
 organisms attached themselves should be quickly liberated from the 
 mass of the protective envelope or sheathing, and fall away from 
 the ship. Nothing, probably, can prevent the adhesion of para- 
 sites, vegetable or animal; and any surface which is permanent 
 will, of course, retain whatever fixes upon it; there therefore 
 clearly remains, as the only reasonable course, to provide some 
 means of obtaining a constantly renewed surface. The electro- 
 chemical action of two dissimilar metals would appear to be the 
 most available, and, so far as our present knowledge goes, to give 
 promise of being the most successftil means of accomplishing this 
 desirable end ; and this at a reasonable and economic price. 
 
 " We have given precedence to what might, perhaps, be regarded 
 as the minor question — the fouling of the ship — because this is an 
 almost permanent and a really very costly phase of the diflSculties 
 to be overcome. Not only is it exceedingly expensive at all times, 
 and particularly perilous and vexatious in that of war, to be obliged 
 constantly at. short intervals to send large ships into dock for 
 cleaning alone, but the retardation of the speed of such vessels is 
 a most serious item, not only in their effectiveness when brought 
 into hostile collision with the enemy, but in involving absolutely 
 •in money expenditure a really reprehensible waste. In regard to 
 the mere operation of cleaning, it is notorious that many of our 
 wealthiest shipowners and some of our finest companies prefer to 
 
 10 
 
146 APPENDIX. 
 
 let their vessels run considerably fouled rather than incur too fre- 
 quently the expensive operation of cleansing in dock their iron 
 hulls. Against this it may be said that the merchant shipowner 
 experiences an additional loss in the laying by of his ship — the 
 most active employment of a vessel producing the most profitable 
 pecuniary result. 
 
 " On the other handj the immense size of our iron-clads would 
 render delays in their getting into dock on account of insufficiency 
 of tides constant occurrences, while similar delays would also 
 happen in respect to their liberation. Thus long and dangerous 
 absences would be common amongst the vessels of our fleets ; and 
 more than possibly at the very time when our utmost naval 
 strength would be wanted, half our vessels might be away, either 
 in dock cleaning, or returning home for that purpose, or on the 
 voyage out again after the operation had been performed. Let 
 us, however, look for a moment as closely as the little light that 
 has been permitted to be shed on the subject will allow, at the 
 money cost involved by this fouling. The ' Diadem/ 800 nominal 
 horse-power, burns sixty tons of coal a day, and does nine knots 
 per ton burnt. Now, if the loss from fouling amounted to one 
 knot per ton burnt, the waste per day of steam fuel would be ^614, 
 adding to which the extra cost of wages for the loss of time on a 
 long voyage or a naval cruise, and other items, would bring the 
 loss to something like £25 a day. Again, if the ' Warrior,' 1250 
 horse-power, and burning not less than 100 tons of coal a day, 
 should lose two knots an hour, or one seventh of her speed, by 
 fouling, the utterly wasted cost of this deterioration of speed — for 
 be it remembered the full quantity of combustion that would give 
 the highest speed with a clean bottom is required to attain with a 
 foul hull this lower rate — would be, supposing English coal were 
 used, £30 a day ; and if fuel had to be bought at foreign stations 
 — a most probable and frequent necessity — this expense would 
 range from any increase up to more than double. "When to this 
 cost of fuel we add wages and other incidents, we shall find that 
 the estimate of £40 a day formed by Admiral Halsted in 1861 
 upon this very loss in this very vessel is really within the mark, 
 and entirely within the actual expenditure. With thirty vessels 
 afloat, and assuming the average loss for each as £30 a day, the 
 total waste for the whole fleet would be £900 per diem, or 
 £339,500 per year, from this one source of fouling alone. 
 
 " To turn now to the second and most important condition — 
 that of the absolute corrosion and waste of the very ships them- 
 selves — we are, as we have already said, all but completely in the 
 dark. We only know the deterioration to be enormous, but in no- 
 way can we estimate precisely its extent. We know, however, that 
 Jong before the introduction of iron ships iron fastenings had to be 
 
APPENDIX, 
 
 147 
 
 abandoned in wooden vessels sheathed with copper; and since 
 iron vessels have heen introduced we know, too, by experience, full 
 well that copper sheathing cannot be affixed to them without the 
 most rapid destruction of the iron being effected. Even if the 
 copper be insulated, the slightest accident that would bring the 
 two metals into contact — and a portion scraped off, or battered 
 together by a collision, or a bolt or a nail driven through, would 
 be sufficient to do this — would set up electro-chemical destruc- 
 tive action; and so frequently and in so many ways would 
 this occur, that all attempts at mere insulation would be almost 
 certain to prove only ruinous snares and delusions. Fortunately, 
 however, the whole question of the corrosion and non-corrosion 
 of iron ships seems to be very simple, and very palpably compre- 
 hensible through the most ordinary knowledge of galvanic action. 
 Iron and copper in the presence of salt water form naturally a 
 galvanic battery, in which the iron, being the weakest element, 
 goes to the wall, while the copper remains intact. If, then, such 
 be the source of the corrosion, it would follow that if we can reverse 
 the condition of the iron iu respect to the other metallic element 
 in the battery, we should save the iron at the expense of that other 
 metal ; and if in selecting another metal, instead of choosing one 
 whose conductivity, readiness to yield to electro-chemical action or 
 any other essential quality, favoured the greatest energy of destruc- 
 tive action, we took a metal possessed of such qualities in the mini- 
 mum practical degree for ensuring a constant renewal of surface, 
 we should have the best possible metal for the effectual sheathing 
 of iron ships ; and thus it would seem that science at once and 
 directly indicates the right road to be pursued. Such a metal 
 exists in zinc, which possesses all the requisite essentials of form- 
 ing a very slowly destructible element in the natural iron-ship 
 battery. And what is very opportune for the confirmation of this 
 view is, that we are not wholly without experimental proof and 
 practical experience. Any one who will simply immerse two small 
 plates of iron and copper in dilute sulphuric acid, and two of iron 
 and zinc in a like solution — in short, form two small batteries of 
 those respective metals — will see distinctly the difference in the 
 destructive action. 
 
 " Iron coated with zinc has been immersed for more than half a 
 year in the sea, and has come out clean, while the surrounding of 
 bare iron has been coated with organic incrustations. Zinc sub- 
 jected to galvanic actibn in sea-water is known to exfoliate with 
 the regularity and certainty of copper, and thus we may be assured 
 no marine growths could find any permanent adherence upon it. 
 As a metal for sheathing it is cheaper than copper in the propor- 
 tion of from one third to one half; and as the cost of sheathing of 
 an ordinary vessel of 400 tons with copper would be about £600, the 
 
148 APPENDIX. 
 
 saving in cost of metal alone in tlie sheathing of our entire iron 
 fleet would be an item of national consideration. It is not, how- 
 ever, in mere money loss that the deterioration of the ships of our 
 navy has to be considered. Their strength and power of resisting 
 shot, shell, and ramming ; their strength of frame to perform the 
 dangerous process of butting, are qualities which it is essential in 
 the very highest degree to preserve beyond all doubt or possibility 
 of deficiency ; and yet visible or invisible corrosion may be sapping 
 the armour plates or eating into the skin of the ship j the corrosive 
 action may be plying its vicious work around the rivets, or between 
 the laps and joints of the plates. Dangers great and small con- 
 stantly are besetting the lives of our great ships, whilst their iron 
 bodies are undefended by any proper clothing — dangers, perhaps, 
 often beyond the ken of -the most active captain or the most 
 efficient inspector, while the result may be that a seemingly 
 stalwart ship may be signalled into action with flushing pride by 
 some brave admiral only to founder with the jar of a self-sought 
 collision, with all its hundreds of gallant seamen on board, into the 
 watery abyss. We do not wish to predict this catastrophe, but we 
 have a right to draw the picture. We wish to make apparent the 
 imperative importance of the subject in every aspect. 
 
 " How far investigations have been carried in the direction we 
 have here pointed out for remedying these serious evils it is, as in 
 everything else connected with this topic, not easy to learn, but the 
 path, if neglected, is in our opinion well worthy of being reopened 
 and pursued ; and whether experimentalists and practical builders 
 hereafter prove or disprove our ideas upon the matter, it will be 
 gratifying indeed if a few years hence we should find any efi'ectual 
 plan in operation, and be able to look back upon any impetus we 
 may have been able to have given towards a fair and impartial 
 investigation of the most suitable remedies." 
 
 The following is the report of the ■ results of the examination of 
 the experimental plates at Portsmouth Dockyard, as taken from 
 the ' Standard' of August 15th, 1866 : 
 
 THE ADMIRALTY AT PORTSMOUTH. 
 
 (prom our own correspondent.) 
 
 " Portsmouth, Tuesday. 
 " Arriving at the new coaling jetty, the board were occupied about 
 ten minutes inspecting some iron experimental plates, prepared by 
 Mr. Daft, to prevent corrosion on ships' bottoms. The inventor 
 explained his theory, and pointed out the results after submersion 
 to the First Lord, who listened patiently, and appeared interested. 
 In your journal of last Friday was a long article on ' The Corrosion 
 
APPENDIX. 149 
 
 of Iron Ships,' and I am enabled to confirm the opinions of the 
 writer on a subject he has so ably handled, and to state in addition 
 that the question is completely solved, as will appear by the 
 following facts which were this day brought to the notice of their 
 lordships. Sixteen months ago two large specimens of iron-plating, 
 three quarters of an inch thick, and about seven feet long by four 
 feet wide, with straps at the back and grooves three quarters of an 
 inch wide left between the edges of the plates, were made at this 
 dockyard. The grooves were filled in with teak, and pared ofi' flush, 
 thus representing a fair flush surface as the hull of an iron vessel. 
 Upon this surface was nailed a sheathing of zinc, a layer of tarred 
 felt being interposed. These specimens, having been immersed in 
 different parts of the dockyard, were this day raised for the 
 inspection of the board. It is sufficient to state the result as 
 witnessed on the jetty. Barnacles, polypi, and weed, were to a very 
 considerable extent clustered about the frame, chains, and bare iron, 
 but the zinc was clean, and entirely free from corrosion. Every 
 nail head was clear and distinct, and there was scarcely the ordinary 
 oxide of metal to cover the surface. Had such a surface as that 
 presented been in motion, as it would have been if fixed on a ship's 
 side at sea, it must have been as smooth as glass. The most re- 
 markable fact related to the Admiralty by Mr. Daft was that nine 
 or ten months ago it was thought advisable by the inventor to try 
 zinc in 'direct contact' with the iron. Accordingly a plate was 
 prepared with grooves in it ; these were filled with teak, as before, 
 and a sheet of zinc nailed directly upon the iron,- minus tarred felt, 
 marine glue, or any interposing material whatsoever. This plate 
 has proved to be cleaner than the others ; the extra exfoliation of 
 ' the zinc, by reason of its actual contact with iron and sea- water, 
 producing, as it does, electro-chemical action, has kept the surface 
 of the zinc absolutely clear of oxide and perfectly smooth. This, 
 then, the simpler plan of the two, is, as usual, the best, and the 
 result entirely sets at rest the question of the fouling of iron ships ; 
 for while the zinc was thus kept perfectly clean, the iron was com- 
 pletely protected from corrosion. I am informed that there is no 
 difficulty in using copper or yellow metal instead of zinc ; but in- 
 sulate these metals how you will, they have the tendency to destroy 
 the iron skin of the ship, which is a disaster of all others to be 
 avoided. Mr. Daft's invention was fully appreciated by the board." 
 
 ZINC SHEATHING FOR IRON SHIPS. 
 
 {From the Standard, August 21st, 1866.) 
 
 " Those theoretical conclusions we had arrived at respecting the 
 possibility of preserving iron ships have received in the short 
 
150 APPENDIX. 
 
 interval that has elapsed since their publication a most decided 
 confirmation from our Portsmouth correspondent, who witnessed 
 the taking up from the harbour there, in the presence of Sir John 
 Pakington and the other Lords of the Admiralty on their recent 
 visit of inspection, of three experimental plates of iron defended by- 
 sheathing of zinc, which had been submerged many months ago 
 by Mr. Daft, of Chelsea. One of these plates was seven feet by four 
 feet, and three quarters inch thick, to which was nailed a sheathing 
 of zinc, a layer of tarred felt being interposed between the metals. 
 Another plate the same size, and sunk in another part of the har- 
 bour, was felted in a like manner. A thir-d, twenty-five inches by 
 sixteen inches, was prepared at the direction of the inventor him- 
 self with the zinc sheathing in close and direct .metallic contact 
 with the iron. That we were not ourselves preseat on that occa- 
 sion is a matter of much regret to us, as the experiments were not 
 only of the highest importance in themselves, but such as it was 
 most desirable should have been witnessed by as many competent 
 persons capable of truly estimating their vast value as possible. 
 Our correspondent there, however, was well able to appreciate 
 their practical character, and his statements may be accepted as 
 thoroughly trustworthy ; but had we had any intimation of the 
 circumstances we should certainly have added our own personal 
 testimony on the subject, as some portions of the experiments 
 seemed to be somewhat unphilosophical, and not easily explicable 
 to an electrician at a distance. In these remarks we allude to the 
 plates which were felted between the iron and the zinc, and which 
 we should have suspected might have fouled unless contact had been 
 made by the nails which fastened the sheathing, or in some other 
 unrecorded way by which galvanic action was set up. Yet if this 
 were so, it seems curious that an insulating materia;l should have 
 been put between the two metals, unless, indeed, the object were 
 to ascertain how slight the galvanic action which would ensure 
 cleanliness of the zinc. Government experiments are celebrated 
 as very hard to comprehend, and as often very mysterious when 
 comprehended. There is nothing obscure, however, about that 
 smaller but most important plate of iron that was sheathed directly 
 with the zinc, neither was there any mistake whatever about its 
 superior and most satisfactory condition. This plate, our cor- 
 respondent says, when taken out of the water, after ten months' 
 immersion, ' proved to be cleaner than the others,' and the ' sur- 
 face of the zinc absolutely clear from oxide and perfectly smooth.' 
 ' This, then,' he adds, ' the simpler plan of the two, is, as usual, the 
 best, and sets at rest the question of the fouling of iron ships ; for 
 while the zinc was thus kept perfectly clean, the iron was com- 
 pletely protected from corrosion.' 
 
 " The testimony of this disinterested eye-witness cannot be 
 
APPENDIX. 151 
 
 neglected by the great commercial and shipping interests of this 
 country, even if the experiments themselves should be by the pre- 
 sent Government, which we do not believe is at all likely, as our 
 correspondent indicates that ' Mr. Daft's invention was fully 
 appreciated by the board.' 
 
 " Since the date of our former article Mr. Daft's plans have 
 been submitted to our careful consideration, and we have ascer- 
 tained from reliable and adequate sources the actual conditions of 
 the Portsmouth experimental plates when drawn out of the har- 
 bour for inspection by the Admiralty. We are therefore justified 
 in drawing further attention to this most important national sub- 
 ject, and that it is a national subject, irrespective of any considera- 
 tion of our navy, the unprbtected condition of the 400,000 tons of 
 iron mercantile shipping which are built every year in the United 
 Kingdom is quite sufficient evidence; and still further to prove 
 ourselves not guilty of the slightest exaggeration in the vast annual 
 amount of tonnage, we give the quantities produced at our chief 
 building stations during the past year (1865), notoriously a bad 
 one for this class of business. On the Thames there were con- 
 structed 117,000 tons; on the Clyde, 130,000; on the Mersey, 
 80,000; on the Tyne, 51,206; on the Wear, 25,000; on the Tees, 
 15,000. In all, on these six rivers alone 408,206 tons of new 
 vessels, to every ton of which Mr. Daft's excellent principle is 
 applicable, were constructed. The world is too large and there 
 are too many active people in it for any individual to know all 
 that is going on, and it is therefore by no means surprising that 
 many private experiments should have been carried out in respect 
 to this valuable project of zinc sheathing which had not reached 
 our knowledge. Such want of information cannot, however, be 
 pleaded on behalf of those late Governments who have now the 
 odium cast upon them of having spent seventy millions of money 
 to no real serviceable end, for Mr. Daft's invention turns out not 
 to be one of yesterday, but to have been made the subject of long- 
 continued study and practical experiment so far as private re- 
 sources would permit, and to have been actually submitted to the 
 Palmerston-B-ussell Government of 1863, while in the following 
 year some plates sheathed with zinc were immersed by order of 
 the Iron Plate Committee, at Shoeburyness, and may now be seen 
 at the South Kensington Museum. Neither has zinc been ulti- 
 mately decisively preferred without the most careful experiments 
 as well as mental consideration. Amongst other trials, two years 
 ago the ' Queen of the South,' a vessel of 2000 tons, had two 
 experimental insulated sheets of yellow metal (not zinc) attached 
 to her iron hull, and which, after two voyages to India and back, 
 of nine months each, remained perfectly clean. To give another 
 case, the steamship ' Alexander,' belonging to the Messrs. Laming, 
 
153 APPENDIX. 
 
 of Leadenhall Street^ has been no less than six voyages with two 
 plates of yellow metal attached to her iron rudder. After every 
 few voyages the 'Alexander' has been obliged to have her iron 
 hull cleaned, but the plates on the rudder have remained smooth 
 and bright ; indeed, the captain has declared that the sheen of the 
 yellow metal was always visible in the clear waters of the Mediter- 
 ranean, and he could always see they were ' all right.' The insu- 
 lation of the yellow metal plates — for be it borne in mind, the 
 perfection of the insulation of the yellow metal or copper is a vital 
 condition both for the keeping clean of the sheathing and for the 
 very existence of the iron ship itself — was effected in a very 
 ingenious manner. Holes were drilled in the iron skin, and plugs 
 of ebonite driven in. Over the iron skin were then laid sheets of 
 felt J over this again was a coating of hard india-rubber. The 
 yellow metal sheets were now affixed by nails driven through into 
 the ebonite plugs. After the ' Queen of the South ' had carried 
 the two plates thus secured for two voyages to India, they were 
 turned back and both rubber and felt found to be in proper con- 
 dition, and the yellow metal in as good order as if it had been on 
 a wooden ship. Why, then, has not this method been practically 
 adopted? Because there has always been this drawback, that 
 metallic contact being made (by a grind against a pier or a quay, 
 or any slight collision with another ship, or by any other common 
 accident that should abrade the insulating material), serious 
 galvanic action would be set up to the detriment of the iron plates 
 of which the vessel was constructed. To put the matter in a 
 scientiiic aspect, we may argue thus : iron being positive to yellow 
 metal, if galvanic action be set up by metallic contact in sea- 
 water, the life of the ship will be in danger ; and therefore why it 
 is that under all circumstances yellow metal should be abandoned 
 for iron ships, and why it is policy to avoid in such vessels the use 
 of both it and of copper. 
 
 '' Having come to this conclusion, we can well understand that 
 Mr. Daft should have sought for some other metal that was 
 naturally positive to iron, and should have found and have proved 
 by a number of experiments that zinc answered all the necessary 
 conditions. Zinc, moreover, is the only metal which, possessing 
 those particular galvanic conditions, is commercially obtainable in 
 either sufficient quantities or at a sufficiently economic price, and 
 zinc, therefore, so far as human prescience can foresee, must be 
 the sheathing metal for iron ships ; and if its endurance be equal 
 on them (as there is no reason whatever that it should not) to that 
 of copper or yellow metal upon wooden hulls, the zinc sheathing 
 will possess the further advantage of being at least two thirds 
 cheaper iu cost than copper. Zinc, then, being preferred, opera- 
 tions have been carried on at Southend Pier and in other parts of 
 
APPENDIX. 153 
 
 the kingdom with uniformly like results, namely, that the iron 
 when the zinc was in metallic contact was invariably preserved at 
 the expense of some slight waste of the zinc — the very condition 
 of things to be desired. The electro- galvanic action between these 
 two metals in contact produces just that amount of degradation of 
 the zinc which the copper and yellow metal have inherent in 
 themselves, and what it is that causes them without contact with 
 any other metal to keep their surfaces clean on a voyage. 
 
 "We are very well aware that on wooden ships zinc has been 
 found to foul to a limited extent, being seldom as bright as copper 
 or Muntz's metal, but in contact with iron the galvanic action is 
 just sufficiently increased to effect that slight degre^ of dissolution 
 or exfoliation, which' makes the zinc the equal of either in its best 
 condition. Have we not, then, here the 0xact effect sought for ; 
 and in zinc a cheap commercial metal which, being positive to 
 iron, slowly perishes itself, keeping clean and bright,- while it pre- 
 serves the iron — ^the skin of the ship ? 
 
 " For a time it was very doubtful if sheathing of any description 
 could be applieid to an iron ship without an elaborate process of 
 drilling, or some other expensive expedient, but the difficulty has 
 been overcome — and by Mr. Daft himself — as completely in the 
 construction of the vessel, as suitable to the application of any 
 metal sheathing whatever, by simply separating the edges of the 
 iron plates used in the skin of the ship and caulking these joints 
 with strips of compressed teak, the process involving less labour 
 than the close adjustment of the ordinary butts, and giving a flush 
 surface eminently calculated for receiving the sheathing. If zinc 
 be used it can thus be nailed directly on the face of the iron with 
 as much facility as upon a wooden ship ; but with this marked 
 advantage, that fewer nails are required to hold it, as the zinc 
 sheets would be much longer than the copper sheets similarly em- 
 ployed for wooden vessels, while the nails, being driven into com- 
 pressed teak, not only jamb tighter, but, having their ends turned 
 by the iron overlaps of the plates, hold vastly faster than nails 
 driven into free timber, 
 
 " Viewed in any or every way, Mr. Daft's process of zinc sheathing 
 is one of the most important inventions that iron shipbuilders 
 and iron shipowners have ever had to consider since the introduc- 
 tion of iron itself as a material for ships, and it is one which, 
 whenever duly appreciated by those most interested classes, will lead 
 to the largest development of the iron shipbuilding trade, as the 
 main reasons for the retention of wood for sailing vessels will be by 
 this means completely abolished." 
 
154 
 
 APPENDIX. 
 
 DAFT'S SHEATHING FOR IRON SHIPS. 
 
 {From Engineering, August 24<th, 1866.) 
 
 " la the course of our report of the nTeeting of the Institution of 
 Naval Architects held in March last, we gave an abstract of a paper 
 read by Mr. T. B. Daft, 'On the Jointing of Plates in Shipbuilding/ 
 the system advocated being that of leaving a space between the 
 edges of the plates, and filling it in with compressed teak, so as to 
 afford a means for readily attaching zinc or other metal sheathing. 
 We now give, in the subjoined figure, a section of a joint constructed 
 on this principle, which will enable us to explain Mr. Daft's system 
 more fully. From this figure it will be seen that the plates are 
 
 
 iiiM 
 
 ^^^fci:^^^^^^^^^^^^Si^^ 
 
 placed upon the joint strip with their edges a short distance apart, 
 and this arrangement being followed for both the horizontal and 
 vertical joints, a groove is thus formed round each plate, having a 
 width about equal to the plate's thickness. Into this groove com- 
 pressed teak is driven, the teak, when expanded by the water, being 
 held so tightly that it is almost impossible to remove it, except by 
 chipping it out. The teak may be compressed in various ways, 
 one method, which answers very well, being the following : — If the 
 grooves to be filled are 4 in. wide, teak planks, rather more than ^ in. 
 thick, are taken and passed between rollers, by which their thick- 
 ness is reduced to -f-in. full. The planks are then reduced to 
 strips 1 in. wide by means of a set of six or eight small circular 
 saws mounted on one spindle, with suitable intervals between 
 them. The teak thus prepared can be readily driven into the 
 grooves, and the excess which stands up above the level of the 
 plates pared away with a plane or chisel. 
 
 "When the teak has been inserted, a perfectly flush hull is 
 obtained, just as if butt joints had been used, whilst the plates may 
 be used as they come from the shears without any after dressing. 
 The manner in which the zinc or other metal sheathing is attached 
 is explained by the engraving, from which it will be seen that the 
 sheathing sheets are nailed by the edges, the zinc nails used being 
 longer than the thickness of the teak into which they are driven, 
 so that their points are turned over, as shown, by coming into 
 contact with the iron skin. The teak is also tightened in the 
 
APPENDIX. 153 
 
 grooves by the nails being driven into it. The sheathing is laid 
 immediately upon the skin of the ship, and at the bow and stern, 
 where the plates are formed to hollow curves, they are, if required, 
 secured by nails driven into plugs inserted in the iron, as well as 
 by those around their edges, which are driven into the teak laid in 
 the grooves. 
 
 "The protection afforded to an iron ship by zinc sheathing 
 depends upon the galvanic action which takes place when the 
 two metals are subjected to the action of sea-water; the zinc, 
 being the positive metal, is gradually dissolved, whilst the iron 
 remains intact. The rate at which the zinc is dissolved is about 
 equal to that at which the ordinary metal sheathing wastes 
 away on a wooden ship, and it is just sufficient to keep the bottom 
 clean and prevent incrustation. In 1864 the Iron Committee 
 tried an experiment on the protective power of zinc sheathing at 
 Shoeburyness, when it was found that a zinc plate -^ in. thick lost 
 •jij- th of its thickness when submerged in the sea for twenty-eight 
 weeks in contact with iron. This amount of depreciation is pro- 
 bably less than would take place if the zinc had been fixed to the 
 bottom of a ship in motion, but still it shows that the zinc would 
 possess considerable durability. The zinc sheathing could be 
 readily replaced, when worn, by stripping it off and renewing the 
 teak in the grooves ; and as this process would probably not require 
 to be performed oftener than once in about four years, it would be 
 less objectionable than the periodical scraping and painting now 
 required. A specimen, representing a portion of the side of a ship 
 as made according to' Mr. Daft's system, has also been tested at 
 the Portsmouth Dockyard, and was inspected by the Lords of the 
 Admiralty during their recent visit to that establishment. In this 
 specimen, which had been submerged sixteen months, felt, satu- 
 rated with waterproof glue, was interposed between the zinc and 
 the skin of the vessel, and the metallic connection requisite to 
 enable the galvanic action to go on was effected by the nails which 
 penetrated the teak strips. On the inspection taking place the 
 surface of the zinc was found to be perfectly clean, whilst the 
 enclosing frame was encrusted to a very considerable extent with 
 barnacles, weeds, &c. As we have stated, Mr. Daft prefers to place 
 the zinc sheathing directly upon the skin of the vessel, and by so 
 arranging it a more perfect metallic connection is of course obtained, 
 and the protective power of the zinc rendered more certain. We 
 hope to hear soon of some more extended trials of Mr. Daft's system 
 of protecting iron vessels, as it appears to be a very promising one." 
 
 The following is copied from the 'Nottingham Daily Guardian' 
 report of the British Association meeting in their journal of August 
 28th, 1866— 
 
156 APPENDIX. 
 
 SECTION G.— MECHANICAL SCIENCE. 
 
 This section agaiu met yesterday morning at 11 o' clocks when 
 the following paper ' On Zinc Sheathing for Iron Ships ' was read 
 by Mr. S. J. Maclde : 
 
 " In science, as in life, out of troubles blessings often arise, and 
 the philosopher, like the man of the world, by the study of the 
 causes of temporary misfortunes, finds out the roads to permanent 
 success. 
 
 " When 400,000 tons of iron shipping are yearly constructed at 
 our six great building stations, on the Thames, the Clyde, the 
 Mersey, the Tyne, Wear, and Teesj and this large quantity has to 
 be multiplied year by year to represent only the bulk of one moiety 
 of the enormous merchant fleets of Great Britain — when to this 
 vast mass of British private shipping we have to add the important 
 item of the iron-clads of our Navy — we may form some idea of the 
 magnitude and the importance of finding some reliable and perfect 
 means of protecting this enormous amount of property from un- 
 necessary destruction and decay. Nor can we confine the subject 
 within even natiojial limits. . Other countries have their iron 
 merchant fleets and their warlike navies, and so while iron ships 
 are sent as iron ships to sea with no protection from wind and 
 water, from rust or fouling, but some utterly inefficient coat of 
 paint, which stops not and only barely hides the mischief which is 
 working out beneath— the question of sheathing iron ships is and 
 will remain one of universal interest — an interest affecting, not 
 only the salvation of a vast amount of wealth, but too often the 
 salvation of many lives. 
 
 " We have long known the great extent of deterioration to which 
 iron ships are subjected, and we have equally long known too that 
 the rapid fouling of iron ships has utterly debarred private ship- 
 owners and our large commercial companies from sending iron 
 sailing ships on long voyages. Wooden ships of old were subject 
 to all the annoyances of fouling until the plan of copper sheathing 
 was adopted — the thin coating of that metal, which possesses under 
 the action of sea the property of always keeping a bright clean 
 surface — why not, then, sheathe iron ships with copper ? Because 
 it could not and cannot be done. The contact of the copper with 
 the iron sets up electro-chemical action, and the iron is destroyed ; 
 the whole ship is converted into a galvanic battery, and its iron 
 skin perishes with more rapidity than if left alone. Still the plan 
 was tried in many ways — the copper was insulated by wood, by 
 gutta-percha, and india-rubber. Glass was tried instead of metal, 
 and, like Admiral Belcher's smelling-bottle in the Arctic Seas, 
 was quickly covered over with barnacles and weeds. So years 
 have rolled away, and still our iron ships are sent as iron ships to 
 
APPENDIX. 157 
 
 sea, and — although some of our national defences cost a million of 
 money apiece — nothing effectual has been done as yet by merchant, 
 shipowner, or Government, at home or abroad. 
 
 " The results so recently obtained at Portsmouth from experi- 
 ments upon Mr. Daft's well-considered plan of sheathing iron 
 ships are so important that I have deemed it an absolute duty to 
 draw the attention of this Association to them, and particularly 
 also to the whole system of zinc sheathing, and to the novel method 
 of putting together the skin of the ship by which the zinc or any 
 other metal plates can be directly applied to its surface. 
 
 " I alluded in my opening words to the advantage to philoso- 
 phers of misfortunes. Mr. Daft, like a true philosopher, has con- 
 verted the knowledge of the cause of the great evil in iron ships 
 into the best and most reliable means for their protection. To cure 
 evil we must do good, and the good is the reverse of the evil. Just so, 
 with the greatest simplicity of thought (for all the sciences, like 
 truth itself, are simple and^comprehensible by all), Mr. Daft has 
 argued — If the galvanic action set up by salt water between 
 copper and iron causes the accelerated destruction of the iron, 
 could we not, by substituting for the copper some other metal which 
 should stand in galvanic relationship to the iron as in the former 
 case the iron stood to copper — that is, if we could find a metal 
 which should be electro- chemically positive to iron — we should have 
 a galvanic battery constituted by the ship and the sheathing, in 
 which that sheathing would be the element to be destroyed and. 
 the iron the element to be preserved. Now, there is but one avail- 
 able metal that would effect this end, and that is zinc, a metal 
 commercially much cheaper than copper. Will zinc, then, do for 
 sheathing ? Will it decompose too fast and require too frequent 
 replacing ? or will it not decompose fast enough to prevent fouling ? 
 These questions Mr. Daft set about to solve by practical patient 
 experiments, in the same quiet, simple, satisfactory natural way as 
 he first conceived the original idea. . The author then showed 
 clearly the difference of effects produced by the actions of salt water 
 upon copper and iron and iron and zinc respectively, in metallic 
 contact, by exhibiting small strips of those metals which had been 
 immersed in two glasses of salt and water the day previous. The 
 results, by a happy accident, Mr. Mackie was able to make visible 
 to the meeting. To bring the plates to the meeting he had wrapped 
 the two pairs of elements in separate papers, and those which had 
 constituted the copper and iron battery had during the few minutes 
 of their carriage to the meeting-room deeply stained the enveloping 
 white paper to a deep red ochreous tint, while the papers containing 
 the iron and zinc elements, although subjected to exactly the like 
 treatment, remained free from any visible stain whatever. Mr. Mackie 
 then pointed out in detail the method which had been proposed 
 
158 APPENDIX. 
 
 for constructing the skins of iron ships, in such a manner that hy 
 caulking the seams with teak a perfect water-tight joint was made, 
 and a plane flush surface secured for the whole hull of the vessel. 
 He also showed that fouling would be prevented entirely by this 
 process of zinc sheathing, because the galvanic action of the iron 
 and zinc in sea-water secured sufficient exfoliation of the exposed 
 surface to keep the zinc as clean upon an iron ship as copper on a 
 wooden one. He also described the practical experiments which 
 had been made at the direction of the Admiralty at Portsmouth, 
 where zinc-sheathed iron plates, which had been submerged in 
 different parts of the harbour for from ten to sixteen months, had 
 been taken up during the past month in the presence of Sir John 
 Pakington and other lords, with not only the iron perfectly free 
 from corrosion, but the zinc sheathing bright and clean, without 
 any barnacles, weed, or other indications of fouling whatever. 
 These and many other details were given in simple intelligible 
 language, and were illustrated by an actual riveted specimen, some 
 two feet square, caulked with teak and partially sheathed with zinc, 
 representative of the actual skin of an iron ship. The speaker 
 further indicated how the galvanic action between the iron skin and 
 the sheathing could be modified to any degree of required intensity 
 of galvanic action, and how builders could form flush hulls upon 
 this plan without its being necessary to plane the edges of the iron- 
 plates to absolute smoothness, as was now obliged to be done in 
 making ' butt ' joints. And now, he concluded, having briefly, I 
 hope intelligibly, put before you the methods Mr. Daft has devised, 
 and which, after mature consideration and experiment, have been 
 found to possess a real and meritorious value, I would urge that 
 the greatest good that can be done to his plan is to detect and 
 criticise every point that seems not merely defective, but to fall 
 short in any way, however slight, of absolute perfection for the 
 purpose for which it was devised — knowing full well that Mr. Daft 
 has refrained from putting his views too quickly before the world — 
 preferring to spend money and time upon satisfactory proof and 
 satisfactory investigations, so that at last he might come forth with 
 his methods substantiated in their value by those best of creden- 
 tials — the record of practical tests ; for whatever shortcomings or 
 omissions there may have been on my part, for whatever further 
 may be desired to be known by any one, every possible facility for 
 information will, I am sure, be given by Mr. Daft, whose most 
 earnest desire now is that his inventions should be convincingly 
 proved to be the proper means of preserving iron ships, and be 
 adopted by shipowners and builders and the Government. And 
 here, in conclusion, let me add that, as the retention of wood as a 
 material for the construction of ships going to India, China, 
 Australia, and other long voyages, is almost entirely due to the 
 
APPENDIX. 359 
 
 present absence in use of any means of preventing fouling except 
 by copper or yellow-metal sheathing, which from their destructive 
 action cannot be applied, so the furnishing of a reliable means for 
 putting on a safe and clean-keeping metallic sheathing will add to 
 the present iron shipbuilding trade — will double the amount of 
 business by bringing into the hands of the iron shipbuilders the 
 construction of the necessary means for carrying on all our great 
 national distant commerce. To this the highest scientific court in 
 the world — if it approves the principles Mr. Daft has worked upon — 
 I would modestly put the vital question, Can a better means be 
 devised than one which nature herself constantly manipulates ?" 
 
 OUR NATIONAL DEFENCES.— THE CONSTRUCTION 
 OP IRON SHIPS. 
 
 {From the Standard^ Monday, Sepiem,ber 24!th, 1866.) 
 
 " The paramount necessity of a thorough examination into the 
 state and condition of the British Navy being evident beyond 
 question, and now not only generally acknowledged by all parties, 
 but the investigation being actually undertaken by the present 
 head of the Admiralty, it is desirable that attention should be drawn, 
 before any decisive steps for reorganisation and construction are 
 determined upon by the Government, to every topic of importance 
 in the construction of iron ships. Wood is a material of the pastj 
 and with its abandonment for war vessels all the experience of by- 
 gone times has been cancelled, and men have had, and still have, 
 to deal with new requirements, new difficulties — to struggle through 
 many dilemmas, and, as in all new operations, to wade through in- 
 numerable trials and failures in the progress towards ultimate suc- 
 cess. That ultimate success in iron shipbuilding is not yet attained. 
 We do not speak now of those debatable matters — broadside ships 
 versus turret ships, or of towering ' Northumberlands ' versus skulk- 
 ing ' Miantonomohs ' and ' Monitors,' nor of wave lines nor wedge 
 lines ; neither have we here anything to do with armour-plating or 
 the stopping out of shot and shell ; but we speak absolutely of the 
 construction of the ship itself, whatever her form or shape or re- 
 quirements may be — the way, in fact, in which the skin plates of 
 iron ships are put together. 
 
 " That there are serious and grave defects in the putting together 
 of ordinary commercial iron ships every conscientious builder must 
 admit, and every novice even can see of this in almost all the 
 merchant vessels afloat conspicuous evidence, if his attention be 
 directed to it. In almost every iron vessel he will see the plates 
 riveted together in two different ways ; he will see the longitudinal 
 
160 APPENDIX. 
 
 strakes have the edges of their plates lapped over each other, and 
 the rivets driven through both inner and outer plates, the contrac- 
 tion of the heated metal of those rivets (which are driven in red 
 hot) in the cooling bracing together firmly the plates, and holding 
 them in a mighty grip that makes the 'lap-joint' stronger even 
 than the plate itself. In almost every vessel we see in the longi- 
 tudinal seams these lap-joints used ; and although this practice 
 necessitates an irregular surface for the skin of the ship that mili- 
 tates against her speed, the ' in-and-out' strake system is so com- 
 mon as to be almost universal, while a smooth or ' flush ' sided 
 iron ship is a comparative rarity. But in all iron vessels we find, 
 further, that although lap-joints invariably form the horizontal 
 seams, another kind of joint is employed for the vertical ends of 
 the plates. These terms, horizontal and vertical^ are used here 
 expressively with a good deal of latitude, for in reality there is no 
 true horizontal or vertical line in the entire skin of a ship ; and 
 what in the side is vertical will be under the bottom, of course, of 
 all degrees of inclination down to absolute horizontality. The term 
 horizontal we apply, then, to all joints or seams running in direc- 
 tions consonant with the length of the ship ; and the term vertical 
 to all joints transverse to these, or in directions from the keel 
 towards the bulwarks above. These terms have crept into general 
 use from the natural habit of speaking of what we can best see, 
 namely, the midship side of the vessel that is out of or above water. 
 In those joints of the plates, then, as we have said, which run from 
 end to end of the vessel, the sides of the iron plates of one strake 
 are lapped over the sides of the plates of another strake, and the 
 rivets driven through the edges of both. But in joining the ends 
 of the plates in these same strakes a totally different kind of joint 
 is used. The vertical edges of the plates are not here lapped over 
 each other, for the abrupt ridges that would be thus created would 
 ofi^er too much resistance to the passage of the vessel through the 
 water, and therefore the edges of the plates are merely brought as 
 close as possible against each other — butted, as it is technically 
 termed — and back straps are riveted on to hold the plates in place. 
 These butt-joints are a source of eternal trouble in merchant ships, 
 and are a source of still more serious anxiety in men-of-war of all 
 sizes and classes. Every pains has been taken, every effort made, 
 by builders to close up and secure these butt-joints, but without 
 avail ; every iron vessel that comes into dock shows something 
 wrong with her butt-joints. In the best yards the edges of the 
 plates are planed smooth, so that they shall fit as exact as possible, 
 but no sooner are the rivets driven than the edges shrink away 
 from each other and an evident crevice appears between them. 
 Then these butt-joints are caulked — that is, the edges of the 
 adjoining plates are driven up together by hammering with a steel 
 
APPENDIX. 161 
 
 chisel, but close as they may be driven, there is still no welding, 
 and the bringing together of the metal is only a hiding of the diffi- 
 culty and the danger, for the operation is little more than surface 
 deep. Tight, however, as the edges may be driven together, no 
 sooner is the ship afloat than her every twist and strain tends to 
 yaw open the butt joints,' and if the tensions be very great, and 
 constantly varying, as in a storm, hundreds of these narrow mouths 
 are gaping to suck in the destructive element, and the iron ship 
 founders at sea. Everywhere in such a case, as one of the pas- 
 sengers of the ill-fated 'London' wrote, 'everywhere the water 
 pours in,' for everywhere all over the ship there are butt joints to 
 tear and bend apart. In an ordinary merchant vessel of 1000 tons 
 there are 400 of these butt joints unceasingly liable to disruption ; 
 but in one of our great iron-clad men-of-war there are no less than 
 from 900 to 1000 such joints, all much more liable, to split apart 
 on account of the momentum and weight of the heavy armour 
 attached above and below the water-line to the skin of the 
 ship. 
 
 " It rarely happens to a man to make two distinct important 
 inventions, and yet it not unfrequently happens that subsidiary to 
 one good thing another is necessitated ; and this has occurred with 
 Mr. Daft, whose admirable and simple plan of zinc sheathing for 
 the preservation of iron ships we recently noticed. To give for the 
 zinc sheathing some firm and convenient means of attachment to 
 the hull was not, as ships have hitherto been built, a very easy task. 
 Doubtless it could be done in a more or less effective manner, but 
 still it would not be a perfect job. There was, then, a necessity 
 for devising some new and superior means in the construction of 
 the ship itself, and Mr. Daft has proposed to open all the joints and 
 leave a space of an inch or more all round the plates, each plate 
 being joined to the other by a narrow back-plate to which each 
 skin plate is riveted by an overlap joint identical with the lap joint 
 of the longitudinal strakes, in this way substituting for the objec- 
 tionable butt joint, what we may term, a double lap joint all over 
 the ship. This novelty in shipbuilding^and that a novelty it is 
 there can be no question, for iron ships cannot be constructed in 
 secret, and everything that has to be done is patent to all the world 
 — we deem of such importance/ as to lay special stress upon it in 
 this article, being satisfied that no valuable improvement will, under 
 the better spirit which now prevails at the Admiralty, be treated '^ 
 with that indifi^erence which during some past years has been so 
 keenly complained of. The Herculean task which Sir John 
 Pakington has entered upon, and which the national safety demands 
 should be barried out to the utmost of efiiectiveness, is a duty in 
 which we have reason to believe the First Lord of the Admiralty 
 will be cordially supported by those heads of departments whose 
 
 11 
 
163 APPENDIX. 
 
 official experiences will be no mean assistance to the best ability 
 and the best endeavours. 
 
 " Moreover, beyond the actual superiority of safety, the saving 
 of expense by the use of the double lap joint for such vessels as 
 the ' Northumberland^ would be no mean item ; for in Mr. Daft's 
 joint it is not required to plane the edges of the plate to a mathe- 
 matical fit ; it is not even required to plane them at all ; and as 
 the present most careful planing and fitting performed at our na- 
 tional dockyards costs over 21. for each butt, the saving would 
 amount in a single ship to more than 2000^. It might, however, 
 be urged that our large iron-clads are so harnessed in armour, have 
 the skin of the ship so supported and strengthened by the exterior 
 armour-plates and their backing of timber, all riveted, and braced, 
 and bolted together, that the outer fabric is made so stout and so 
 rigid, that the inner and proper skin only constitutes a small item 
 in the external hide of the vessel. But this would be a grave mis- 
 take, and yet it is one constantly made by writers who criticise 
 the works of naval architects and the qualities of ships and ship 
 batteries, without ever having seen a ship built, and perhaps with- 
 out having been on board one. Neither is it an uncommon mis- 
 take made in society to suppose that the whole skin of an iron-clad 
 is made of unusual thickness and solidity, many persons forgetting 
 or not knowing that the under-water part or bottom of the iron- 
 clad ships of is thin iron, such as would have been used had the 
 vessel been an ordinary one ; but this thin iron is strengthened by 
 a webbing of deep flat ribs, extending from the outer to an inner 
 iron skin, all being brought up to a flat ledge, upon which the 
 armour-plating and its backing (which only extends as a belt round 
 the ship for some feet above and some feet below the water-line) 
 is rested. As much thinness as is barely consistent with safety is, 
 therefore, adopted for the plates forming the nnder-water hull, in 
 order to diminish as much as possible the weight of iron used in 
 the ship. In point of fact, the designer of an iron-clad may be 
 said to take off as much iron as he dare from the general hull of 
 the vessel, in order that he may put as much armour as the flota- 
 tion will allow round the ship's water-line and battery. All the 
 evils, therefore, that an ordinary ship is subjected to, and especially 
 that most serious one of all, the yawing open under her strains of 
 the butt joints, are vastly increased in an iron-clad by the momen- 
 tum and weight, and even the rigidity of the armour-band around 
 the ship ; .and the thicker and more rigid the armour applied, the 
 worse the strains upon a thin-skin bottom will be in their eflects 
 upon the joints. 
 
 " There are anomalies, moreover, in iron shipbuilding, as in every 
 other branch of practical science. The tensile strength of an iron 
 plate is greater than its strength when in compression. Under 
 
APPENDIX. 163 
 
 tension, the iron plate requires a strain of 20 tons to the square 
 inch to break it; but 12 tons in compression is enough to crush it. 
 The strains, too, upon the skin plates of a ship are as different in 
 value as they are in their character j and as there are two kinds of 
 joints, the effects of tension and compression will be differently- 
 manifested in their influences. The lap joints, themselves as strong 
 as the plate, are always subjected to tension, and never to com- 
 pression, because, come which way the strain may, it always exerts 
 a tensile pull upon the plates and a shearing strain on the rivets. 
 The butt joints have no value in tension, but are subject to com- 
 pression, and then the worst joints in the ship have to sustain that 
 strain to resist which the iron plate itself is least competent. For 
 as the shearing strain, or that strain which will 'shear' off the 
 rivets, is 20 tons to the square inch, it is equal to the breaking 
 tensile strain of the solid plates themselves ; whilst, when the ends 
 of the skin plates are in abutment against each other in the butt 
 joint, the breaking strain of the solid plates by compression is 
 12 tons, and therefore the strength of the hull of any vessel having 
 butt joints must be regarded at the lesser value of 12 tons to the 
 square inch, and not at 20 tons, as it might be if all the joints in 
 the ship were lap joints. But there are still other points to con- 
 sider in the vibrations and torsional strains to which iron ships are 
 subjected. We have spoken of 12 tons as the limit of the com- 
 pressive strain ; but this, it must be remembered, is the limit when 
 the plates are perfectly straight and brought fairly in opposition — 
 conditions which, it may be said, never happen in a ship, every 
 line of which is a sweep of greater or less deviation ; and the con- 
 sequence, therefore, of the butt joint is, that the skin plate yields 
 by buckling at a still lower strain of 6 or 7 tons to the inch, while 
 the leverage of the buckling is exceedingly likely to snap off the 
 rivet-heads. In order best to understand the difference of strength 
 between a butt joint with a back-strap, and a double lap joint 
 riveted to a narrow back-plate, let us suppose the butt joint and its 
 back-strap to be one solid homogeneous mass of metal. Would 
 anybody be mad enough to cut the joint half through with a saw? 
 Nevertheless, this half cut-through joint would be all but identical 
 with the ordinary butt joint. Anyone would see, if the solid joint 
 was half cut through, that at every bend of the ship the cut would 
 be liable to be opened, and that every opening would be likely to 
 rend further and further the gash. And this is just what happens 
 when the butt joint is made to yaw by the snake-like torsions of a 
 ship labouring at sea. All the leverages of the two plates are 
 brought to bear upon the back-strap at the line of the butt joint, 
 and all the resistance is thus made to fall solely upon the line of 
 particles in the back-strap opposite to that joint; the more perfect, 
 therefore, the butt joint is made to keep out the water, the more 
 
164 APPENDIX. 
 
 smoothly it is planed, the more closely it is fitted, the more dan- 
 gerous is its tearing tendency upon the back-strap, and the more 
 dangerous its real character in respect to the safety of the ship. 
 On the other hand, by separating the edges of the plates but a 
 single inch, we have done away with the butt joint, we have done 
 away with the dangerous crack, we have made two of the strongest 
 kind of joints (lap joints), instead of one of the weakest, and have 
 allowed a sufficient interval of metal between them 'to bend into a 
 curve when the strain comes upon the back-plate, and to bend back 
 again into position when the strain is released, if the metal pos- 
 sesses sufficient resilience to do so. We have, in short, produced 
 a very narrow strake, which we can iron-caulk first if we please, 
 and then fill up with an effective caulking of wood, not only to nail 
 the zinc sheathing to, but to complete a watertight joint ; at the 
 same time, the whole hull of the ship is completed flush and fair 
 from one end to the other in every direction alike — a consumma- 
 tion never yet accomplished, nor possible, under the former pro- 
 cedures in building, except at a dangerous and unwarrantable use 
 throughout the entire vessel of the untrustworthy butt joint. That 
 the number of joints is increased under Mr. Daft's plan is no detri- 
 ment to the vessel ; on the contrary, it adds to her stiffness ; and 
 the cost of any additional metal and riveting is more than com- 
 pensated in the saving of labour and machinery for planing the 
 plates. Moreover, the actual weight of the slight additional quan- 
 tity of iron required for the back-plates is also more than compen- 
 sated by the increased capacity of the ship ; for in the bringing 
 out of the in-strakes to flushness with the out-strakes there has 
 been the gain in every other strake of the thickness and width of 
 an entire strake to the internal dimensions of the ship, and, conse- 
 quently, an equivalent increase of her buoyancy. Thus constructed, 
 there are no inequalities whatever in her skin to interfere with her 
 speed through the water, nor any ledges to form first shelters for 
 the attachment of weeds and barnacles. 
 
 " The remarks we have made so far apply equally to iron ship- 
 building for the merchant service as for the navy, as indeed will 
 most of the comments we have hereafter to make. There are some 
 points, however, which apply peculiarly to men-of-war, and others 
 which have more pointed force in respect to them than to any 
 other classes of vessels. In respect to iron-clads we have seen how 
 essential it is in every way to give the greatest strength to the 
 proper skin of the ship in order to support the armour-plating as 
 well as to resist the strains upon the hull below water, where the 
 greatest yawing action will necessarily take place. And yet we 
 have seen, too, that this very under- water portion is purposely 
 kept as thin as possible to give more flotation power to the ship. 
 How vital then in importance is the plan of any joint which. 
 
APPENDIX. 165 
 
 without increasing tlie thickness of the skin by a single line, 
 should raise its breaking strength from 6 or 13 to 20 tons the 
 square inch of metal. 
 
 " Nor in this consideration must we overlook another important 
 feature of strength or weakness in an iron ship — the riveting. 
 Whatever may be the quality of our plates, however high their 
 tensile or compressive resistance, all may be set at nought by bad 
 or defective riveting. And to rivet well large plates under the 
 system of in-and-out strakes, now so universally prevailing, is no 
 easy or generally accomplished matter. The large skin plates of 
 one strake have to -be held in place against those of another strake 
 already fastened to the framework of the ship, and the rivet-holes 
 of the attached plates have to be marked througli their punched 
 holes (or a similar process adopted) upon the plates next to be 
 fitted. The plates so marked have then to be held under the 
 punching machine, and each mark has to be punched as near as 
 men's hands will guide great plates 10 ft. x 3 ft. under the 
 punches. It is very easy to believe that under these circumstances 
 the rivet-holes of the plates of one strake do not always properly 
 'look at' the rivet-holes of the plates of the other strake that areto 
 come over them ; and that the practical consequence is either that 
 smaller rivets than the diameter of the punched holes are used, or 
 that the punched holes are ' rhymered ' or opened to admit 
 bigger rivets, which are' often driven in in a contorted form, or 
 with only half their proper diameter coming fairly through both 
 plates, and thus being seriously weakened in their strength. 
 Under Mr. Daft's plan all the large skin plates of the ship can be 
 punched with rivet-holes by a suitable adaptation of the machinery 
 at mathematically accurate distances apart; and after they are 
 fitted to the ribs of the vessel it is evident that the holes of the 
 handy-back plates can be so exactly punched that when they are 
 fitted to the skin plates every rivet-hole will be so truly in position 
 with every other that the professional ' squarer ' will have a 
 sinecure office in all but his inspections. 
 
 "Two decisive advantages are thus derived entirely from this 
 simple but ingenious plan of double lap-jointing the skin plates on 
 to a narrow back-plate, namely, the full strength of the iron plates 
 is brought out, and the strength of the ship most materially 
 increased without any increase whatever in the dimensions of the 
 skin plates ; and secondly, the perfection of the riveting is ensured, 
 thereby getting rid of a serious danger "that in ships as -now con- 
 structed is only masked from eyesight and inspection, and is all 
 the more treacherous that it passes uncared for in a fallacious belief 
 in an unreliable security. 
 
 " Another point also deserves the most prominent attention — the 
 greater rapidity with which ships can be built on the Daft principle 
 
166 APPENDIX. 
 
 than on any other, arising mainly from three causes. First, that 
 the large skin plates and the angle-irons, or ribs, may he both 
 accurately punched without the usual to-and-fro labour, and the 
 lifting about of these ponderous masses, and the plates being ready 
 to hand, may be attached as fast as possible to the ribs ; secondly, 
 the narrow back- plates being easily and accurately adjusted, can 
 be riveted on with the greatest rapidity, their smaller size allowing 
 much more readiness of adjustment as well as greater facilities of 
 handling ; thirdly, all the time and expense of planing and fitting 
 the butt joints are totally and altogether got rid of. To give an 
 illustrative instance of the value of this gain of time in iron ship- 
 building we may take the ' Northumberland ' as an example. That 
 ship is of 6000 tons dimensions, and to build in the ordinary - 
 manner would not, under the utmost efforts, he completed within 
 two years. By using the Daft joints such a ship could be finished 
 in twelve months, and at a pinch even in ten months. And this, 
 too, be it borne in mind, with an increase in absolute strength, 
 much greater rigidity, and no liability to the yawing open of joints, 
 the last, the one greatest diflSculty in the structure of iron ships, 
 and a difficulty insuperable with any other material j the difficulty, 
 in fact, which absolutely prohibits the use of wood in armour-clad 
 ships, for no bolts would ever hold tightly together the under- 
 water hull of a wooden ship weighted with a heavy belt of metal 
 armour j nor can wood and iron be used together with any degree 
 of safety or any possibility of endurance. Whether, therefore, 
 Palliser shells, or any other missiles, will penetrate them or not, 
 iron is the only available material for ships, and the time is 
 approaching when not a wooden vessel will be spreading her sails 
 upon the face of the ocean. 
 
 " To Mr. Daft belongs the merit of having patiently devoted 
 himself for years to the working out of one great problem — the 
 preservation of iron ships from corrosion and fouling, and in doing 
 this he has incidentally improved the method of building." 
 
 Standard, December 25th, 1866. 
 
 THE PRESEEVATION OF OUR IRON WAR SHIPS. 
 
 " Age improves nothing that we know of but good wine, and 
 even that is not benefited by being too long in bottle. Iron ships 
 are no exception to the general rule of decadence, and as we have 
 already pointed out, some months ago, our most costly magnificent 
 naval defences are not improving in condition. Amongst all the 
 many interesting and instructive topics touched upon in the recent 
 lecture of the Chief Constructor of the Navy at Plymouth not a word 
 
APPENDIX. 167 
 
 fell from him upon one subject of vital importance to the nation — 
 the corrosion of our iron-clad men-of-war. Mr. Reed's objects and 
 intentions are very apparent in his address. He desires evidently 
 to justify his own past course and his own accomplished works 
 against the opposition they have had to encounter, and to indicate 
 the direction in which he wishes his future work to proceed. His 
 comments upon long ships and short ships indicate the first desire ; 
 and his advocacy of steam ships without masts, and his expressed 
 preference for wholly iron ships over wooden ships cut down and 
 plated, are evidence of the last. In both cases he has scientific 
 juistifications of very valid character. Every subject could not 
 necessarily be handled in one discourse, and what he did do was 
 very much. Still, one can but regret that we did not learn some- 
 thing as to the real amount of deterioration our iron-clad vessels 
 have actually suffered, even before they have all been furnished 
 with their proper armaments of guns. Nothing reliably effective, 
 so far as we can learn, is being done to preserve our iron ships 
 from either corrosion or fouling. And yet there is an effectual 
 means of doing both; but not by the plan we hear is being favoured. 
 It might have been all very well, while nothing better was known, 
 to cover the hulls of iron ships with anti-corrosive paints, glass, 
 stucco, or cement; but these only afford better sui'faces even 
 than the iron for the adhesion of the barnacles and weeds j or 
 to apply corrosive sublimate or phosphorus to poison the said 
 barnacles and seaweed that would not be killed, and which lived 
 on and grew and flourished in utter disregard of their strongest 
 virulence. The last official fancy would appear to be to sheath or 
 to " pack," as it is technically termed, the iron ship with wood, 
 and then to cover this over with copper-sheathing; thus in the 
 case of wood-packing (the material selected) making the ship of 
 bigger bulk, and causing the ships practically to drive a vessel six 
 inches larger in every direction than she ought to be, or was in- 
 tended to be, through the water against so much greater and entirely 
 wasteful resistance, whilst at the same time the ship is left subject 
 through the slightest abrasion against the pier or graze against any 
 other object, the careless driving through of a bolt, or any accidental 
 contact made with a common nail, to the possibility, nay, the very 
 certainty, of accelerated destruction, for the instant galvanic action 
 is set up between the copper and the iron, the destruction of the latter 
 is increased to a most dangerous degree. Nor is the avoidance of 
 absolute contact of metal with metal in the actual construction of 
 the ship a perfect security against such deleterious results, for the 
 merest scraping off of the copper sheathing that would permit the 
 sea water to penetrate the seams of the wood planking beneath, or 
 even the saturation of the wood itself, with salt water, would be 
 equally effective in setting up destructive galvanic action as if the 
 
168 APPENDIX. 
 
 iron hull and the copper sheathing were in the closest contact. 
 Felt, gutta percha, india rubber, are even more treacherous than 
 wood planking, because, being thinner, they are much more liable 
 to abrasion and injury. And yet all these primitive and abortive 
 means are continued in vogue, whilst a more perfect, more simple, 
 less costly, and thoroughly efficacious system is known to exist, 
 and has been proved to possess all the .excellences claimed by its 
 inventor, and this too by the very officials who seem afraid to act 
 upon the proof afforded by their own experiments. Iron and wood 
 and iron and copper never did, never can, never will, agree toge- 
 ther in a ship. Iron, therefore, must either stand alone and de- 
 compose at its own particular rate, or it must be put in combina- 
 tion with some other metal from contact with which it will not 
 suffer. This metal has been proved to be zinc. In August last 
 the second series of trial plates of zinc sheathing attached direct 
 upon the surface of iron skin plates submerged under the orders of 
 the Admiralty, was taken out of the harbour of Portsmouth in such 
 a state of perfect cleanliness, after an immersion of sixteen months' 
 duration, as to leave no reasonable doubt as to the thorough effi- 
 cacy of the plan. A first series had been previously deposited in 
 the sea at Shoeburyness in 1864 for nearly seven months, by which 
 it was definitely proved, as the second experiments have confirmed, 
 that zinc sheathing stands to iron ships in the exact correspondence 
 with copper upon wooden ones. But although the first series 
 showed that zinc plates of l-27th inch lost l-24th of their thick- 
 ness during their submergence for 38 weeks in contact with the 
 iron, and the second series confirmed this gentle rate of waste, yet 
 the second series, after their 16 months of trial, have been put 
 down again at Portsmouth into the water, either to ascertain to a 
 grain the exact loss of weight of zinc, or for some other minor 
 purpose not at all intelligible to any chemist or electrician. The 
 official manipulations that were made with this very series when 
 they were primarily put down by order of the Admiralty seem per- 
 fectly inexplicable. Why, for example, felt saturated with water- 
 proof glue should have been interposed between the iron plates and 
 the zinc in some of the specimens then submerged, may be ex- 
 plained by the Government chemist, but we do not think ever will 
 be by any one else. If anything could have been devised to frus- 
 trate the success of Mr. Daft's method, nothing more likely than 
 this could have been conceived ; and that it would have prevented 
 success is certain if the metallic contact had not been secured by 
 the driving through of the nails which held on the sheathing, for 
 the zinc system depends for its efficacy upon that very conditionof 
 contact which is ruinous in the case of every other metal. As we 
 know that some of the most important of our national experiments 
 during past years under Whig governments have been totally viti- 
 
APPENDIX. 169 
 
 ated by blunders which might have been accidental or might have 
 been intentional, it is not unnatiiral that competent men should 
 scrutinise closely any interference with inventors' original plans. 
 
 " At this particular period, when there is a lull in the progress 
 of our national shipbuilding, and the ministers themselves are re- 
 ported to be irresolute as to the courses they shall determine upon, 
 it is more than ever desirable that the many undoubtedly valuable 
 novelties which are ready for adoption should neither be overlooked 
 nor set aside. The new process of zinc-sheathing has caused a 
 most important improvement in the way of putting the plates of a 
 ship together, by which greater strength and greater security are 
 attained in combination with a smooth hull. The advantages of a 
 perfectly flush surface are too evident to be dwelt upon ; and what- 
 ever may be surmised on behalf of wooden vessels, we cannot help 
 feeling the strongest conviction that the days of wood are com- 
 pletely passing away, whether for naval or mercantile purposes. 
 We have long urged the construction of iron ships, and have de- 
 clared our disbelief in wooden ones. Mr. Reed has well put the 
 case in his remarks on the conversion of our wooden broadside 
 ships into iron-clad turret-ships. Captain Coles's plan, we have 
 no hesitation in saying, can never have proper justice done to it in 
 any other material than iron. No other would do for the turret, 
 no other could be effectually employed in the ship which should 
 carry it. Wood can never be suflBciently bolted together with 
 wood trenails to carry heavy armour plates, and if fastened with 
 metal bolts, the strain by the ponderous plating and heavy weight 
 of the armament is ever tending to tear open the bolt-holes, and 
 thus to damage the hull. Iron, riveted together with a firmness 
 nothing can exceed, must be the material, and as our war-ships are 
 constructed of thicker and more costly plates of metal, the greater 
 the cost and the more the need to take the most effective means 
 for their preservation. What we want, then, particularly to draw 
 attention to in this article is the plan of coppering upon wood- 
 packing, at present in favour with the Admiralty ofi&cials, and now 
 being tried, we understand, upon one of the iron ships in the Pem- 
 broke Dockyard. The sheathing is, of course, intended also to 
 keep the ship's hull clean, for the cost of docking and scraping our 
 iron vessels is very severe. Of the real value of anti-fouling nos- 
 trums in the form of varnishes and paints, there is ample proof. 
 In September, 1864, for example, the 'Achilles' was examined by 
 a professional diver, who found her bottom covered with barnacles 
 and weeds, some of the latter being as much as two feet in length ; 
 and at this moment the 'Valiant' is said to have weeds of the 
 length of more than, two yards attached to her hull. The condi- 
 tions of iron vessels coated with Mr. Hay's composition two years 
 ago have evidently not yet been improved up to this hour. Pea- 
 
170 APPENDIX. 
 
 cock's and other similar compounds have also had sufficient trial ; 
 and, setting aside the natural-history aspect of the question, expe- 
 rience sufficiently shows that anti -corrosive varnishes must be 
 sooner or later obliterated from actual use as preventives against 
 that most serious interference with the speed of sea-going ships. 
 Now, copper sheathing over wood packing on an iron ship will be 
 of no more service in preventing fouling than Hay's composition, 
 glass, or stucco, or the absolute surface of the iron itself, as soon 
 as there is any contact between the iron of the ship and the copper 
 of the sheathing, for directly such contact is made, the iron will 
 suffer destruction while the copper sheathing will no longer un- 
 dergo exfoliation, but, having its surface preserved, will become a 
 permanent basis for the growth of all kinds of weeds. Such me- 
 tallic contact may be made accidentally in the putting on of the 
 sheathing or packing, or the. fixing of the iron holdfasts for the 
 rigging. It may even be established by the overhanging of any 
 ordinary iron chain upon the vessel's side. It is, therefore, evident 
 that no amount of plugging over iron bolt-heads, or any other pre- 
 cautions which may be taken, can even secure the constant insula- 
 tion of the copper from the iron. If, then, absolute immunity 
 cannot be certainly insured, it is evident that a plan which is open 
 to such numerous casualties cannot, and ought not, to be relied 
 upon. This system of ' packing,' too, increases, as we have pointed 
 out, the size of the ship. Now, as every square foot of midship 
 section takes one nominal horse-power to drive the ship at the rate 
 of ten knots per hour, so will the difference between the packing 
 or extra midship section and the original skin of the ship use up in 
 proportion the steam power. 
 
 "If the beam of the vessel be taken at 60 feet, and regarding 
 the curve of the hull under water as 90 feet, then a thickness of 
 packing of four inches all over the bottom will give 30 square feet 
 additional midship-section, and this will absorb steam power to the 
 extent of 30 nominal horses. Thus it will be seen that as this 
 packing is a permanent addition to the size of the ship, so it incurs 
 an everlasting expense for fuel and a constant waste of power, as 
 well as being a serious drawback to the speed, the last being one 
 of the highest essentials for a modern man-of-war. Any diminu- 
 tion in the thickness of the armour plates from corrosion, we need 
 scarcely say will materially diminish the fighting qualities of the 
 ship. The reverse of the estimated gain by additional thickness of 
 plate will take place, and the loss of an inch upon a 9-inch plate 
 would, of course, reduce its resistive strength from the square of 9 
 to the square of 8, or in other words from 81 to 64. 
 
 " Moreover, to this plan we have thought it most important to 
 draw public attention on account of its insidious danger ; and it is 
 also desirable to put it in direct comparison with the method of 
 
APPENDIX. 171 
 
 zinc-sheathing. To convey some idea of the principles involved in 
 the two systems^ we may point out that when two plates of 
 different metals are brought together in actual contact in salt- 
 water, an electro-chemical element is constituted, and this condi- 
 tion of a single- element remains good, whatever may be the size of 
 the plates, the quantity of the electrical force being in direct 
 proportion to the superficial dimensions, that is to say, that the 
 effect produced upon each superficial foot of surface is absolutely 
 alike over the whole plate, one plate being in one kind of electrical 
 condition and the other in the opposite, one metal consequently 
 being preserved whilst the other is perishing. In other words, to 
 express the matter scientifically, zinc being the more oxidisable 
 metal converts the iron into a positive electrode, thus placing it in 
 the like position as copper stands in relation to iron, though not 
 nearly in so strong a degree. Iron, it is well known, is, when in 
 contact with copper, eaten away at a very rapid rate, while the 
 copper is preserved, and fouls at sea with weeds and the customary 
 marine organisms. Zinc in place of copper upon wooden ships 
 has not sufficient exfoliating action to keep a clean service, but 
 slightly coating soon permits of fouling; hence why zinc has 
 fallen into disuse for wooden vessels. But when zinc as sheathing 
 is made to constitute in contact with the iron skin or armour of a 
 ship a single element, then the galvanic action induced hastens the 
 destruction of the zinc in the same ratio as it preserves the. iron. 
 This property of the zinc ensures that essential condition of a 
 constant peeling or flaking which always presents a clean metallic 
 surface, and is the only preventive of the fouling of ships. "We 
 revert to the insidious nature of the mischief which will go on 
 under the wood packing. This mischief, it is clear, will be totally 
 masked by the 'packing,' and never can be known but by 
 stripping the hull. It is not likely any periodic stripping and re- 
 packing will be encouraged at head-quarters, for the expense 
 would be double that of the original operation of covering the ship ; 
 and it is equally certain that without this nothing could be known 
 of the injuries progressing until they made their indications in the 
 interior of the ship, and then all would be too late for remedy. 
 
 " The plan of coppering over wood packing is open, therefore, 
 to these serious objections : — It is exceedingly costly as well as 
 difficult to fix the wood packing on to the iron skin of the ship ; 
 no tliickness of wood will secure immunity from the penetration 
 or permeation of the salt water which constitutes the bath of the 
 galvanic battery formed by the two metals ; that while constant 
 insulation cannot be ensured even in the face of the many accidents 
 to which ordinary ships are subjected, the shot-holes and other 
 injuries to which men-of-war are liable will add frightfully to the 
 increase of the causes of such injuries; that copper sheathing. 
 
172 APPENDIX. 
 
 even when separated by wood, felt,, or gutta percha from the iron 
 hull is not proof against fouling ; and, lastly that the copper is 
 constantly liable to aflfect the iron hull to the extent that in six 
 ■weeks an half-inch plate may be entirely eaten through. 
 
 " On the other hand, it will never do to leave the iron alone, for 
 as everybody knows, who knows anything at all about iron ships, 
 their corrosion is an item of the most serious consideration." 
 
 The following letter appeared in the ' Standard ' of the 28th 
 Dec, 1866, from Captain McKillop, who it seems has been direct- 
 ing his attention to the use of zinc for sheathing iron ships. 
 
 PRESEUVATION OF IRON SHIPS. 
 
 To the Editor. 
 
 " Sir, — Your admirable article on the preservation of our iron 
 war ships ought to be carefully read by every one who from chance 
 or position has any dealing with, or authority over, iron ships of 
 any class. 
 
 " The experiments made with zinc sheathing placed directly on 
 the surface of the iron plates have undoubtedly proved that galvanic 
 action, which precludes the possibility of copper or iron being used 
 within reach of that most insidious action, is made to fulfil the 
 object aimed at (viz., the prevention of encrustation and growth of 
 weed), by the very process which is fatal to the combination of the 
 other metals even when so-called insulation is established, which 
 has over and over again been demonstrated. Having for many 
 years paid much attention to this subject, and examined the 
 bottoms of hundreds of iron ships coated with every imaginable 
 compound, from quicksilver to cow dung, I was much interested 
 in the successful issue of the zinc sheathing, and very much 
 puzzled to know why a counter experiment should be tried with 
 these metals by placing between them the glue and felt as an in- 
 sulator to kill the very process which had proved so useful. Really 
 one would imagine that the Admiralty chemists' nostrums must of 
 necessity be introduced in some shape or other to mar every 
 attempt to solve the question. The marine glue could not be more 
 out of place if dissolved in the castor oil served out to the Royal 
 Navy. 
 
 " Mr. Daft's experiment on stationary plates has undoubtedly 
 been successful, and the wasting or exfoliating process of the zinc 
 has been only sufficient to fulfil the object in view; but this 
 process would be very materially increased by the rapid action of 
 the ship passing through the water. About sixteen months ago I 
 zinc-sheathed the bottom of a floating powder magazine for Messrs. 
 Joho Hall and Sons, which has ever since been moored below 
 
APPENDIX. 173 
 
 Gravesend, subject to the action of the tide. This vessel was an 
 old man-of-war, and, of course, has a great quantity of copper in 
 her frame and planking. I was fearful of bad results from the 
 effect the copper might have on the zinc. I therefore chunamed 
 the bottom previous to applying the zinc sheathing, before the 
 chunam had time to harden. The result up to the present is most 
 satisfactory, and in several places where small portions of iron 
 have been covered with the zinc it shows decidedly a cleaner surface, 
 but the zinc is considerably more worn, in one instance right 
 through. I must, however, explain that the water has no doubt 
 access between the iron and the zinc. The average rate of the 
 tide at the spot where the magazine is moored is not more than 2 J 
 knots for a period of nine hours out of the twelve. The thickness 
 of the zinc is l-16th of an inch. I venture to send you this in- 
 formation, as I think that the subject is one of such vital 
 importance, if we are to go on building iron ships, that every item 
 of information is worth recording, — I am. Sir, &c., 
 
 "Dec. 26. "R. P. McKillop, Capt., R.N." 
 
 ON THE CONSTRUCTION OF IRON SHIPS; 
 
 And their Preservation from Corrosion and Fouling by 
 Zinc Sheathing. By S. J. Mackie, Esq. A paper read 
 before the Society of Arts, April 24th, 1867 ; C. W. Siemens, 
 Esq., F.R.S., C.E., in the chair. (Reprinted from the ' Journal 
 of the Society of Arts.') 
 
 " In view of the magnificent total of British iron ships, I need not 
 apologise for taking a survey of the state in which they are kept, 
 and the manner in which they are built, in order to show that they 
 are neither built nor kept as they ought to be, if I can succeed in 
 proving that iron ships might be better built and better kept than 
 ever they have been. Still more shall I be justified in calling 
 attention to these subjects if I can further show that the present 
 depression in the iron shipbuilding trade may undoubtedly be 
 released, and double the amount of tonnage of ships annually con- 
 structed hopefully expected for the future of the iron shipbuilders. 
 
 " For my own part, I am the more free to speak boldly and un- 
 reservedly, in that I am not about to advocate any plan of my own 
 for the remedy of the evils that exist. To my mind there is but 
 one right way of doing everything that has to be done. Men did 
 not build ships when they first began to navigate the seas, but 
 scooped out into canoes the trunks of trees, such as had served 
 them for sitting astride to cross the rivers in their way. Nor did 
 they, when wanting vessels of burthen to carry interchangeable 
 commodities for longer distances, build wooden vessels as large as 
 
174 APPENDIX. 
 
 the East Indiaman of the last century^ or as swift as the American 
 clipper of this. So iron shipbuilding, although a modern invention, 
 did not start into existence in perfection, but has gone through 
 various modifications and improvements, until it arrived at its 
 present eminent condition. Progress has still to be made. Far be 
 it from me, however, to deny, or to attempt to diminish the ability 
 and the perseverance of the eminent engineers and practical 
 thinkers who have foreseen and avoided so many difficulties, and 
 have encountered and conquered so many more, nor to undervalue 
 the experience and skill of constructors and skillful workmen. Nor 
 can it be my wish in any way to detract from the deservedly high 
 fame which the English and Scotch iron shipbuilding yards have so 
 far maintained. But there may be a time in the history of iron 
 shipbuilding, as there has been in most other great branches of 
 manufacture and commerce^ when those who have got a long way 
 towards perfection, become enamoured with what they have done, 
 and think nothing better to be possible. Such is, to a regretable 
 degree, the present condition of iron shipbuilders. Having done a 
 great deal, there is no disposition to go a step further, although it 
 be but one step further that is required, to make modern ship- 
 building as perfect as, in the present condition of science, is possi- 
 ble. The corrosion and fouling of ships may be said to be no 
 business of the shipbuilder ; and most men engaged in the trade 
 might possibly admit that cleaning, repairing, docking, and tin- 
 kering, constitute a very large proportion of tlie shipbuilder's busi- 
 ness. But herein lies a serious error. Shipowners and merchants 
 are undoubtedly more closely concerned in the preservation of the 
 ship, and in her cleanliness and speed at sea ; but if the capacity 
 of keeping a clean hull would create an additional demand for iron 
 ships, is not the means of effectually preventing the fouling of an 
 iron hull in salt water well worthy the attention of the iron ship- 
 builder ? 
 
 " Such a means exists, and has been proved undeniably by expe- 
 riments, and yet there is no disposition to give it practical adop- 
 tion; a fearful evil exists in the unmechanioal butt joint, and yet 
 iron shipbuilders go on planing, and caulking, and fitting at enor- 
 mous cost, and boast of the beautiful work that sends every iron 
 ship afloat to sea, with the most effectual device for her destruction 
 which the highest scientific knowledge and the most practical in- 
 genuity could conceive. If our commercial shipbuilders will not 
 take the lead, we cannot wonder that the artificers in our naval 
 dockyards are still permitted to pride themselves on the fallacious 
 finish of their butt joints; and while shipowners spend thousands 
 of pounds in docking and cleaning their ships, allow corrosion and 
 decay to have unlimited rule, and besmear the hulls of vessels worth 
 tens of thousands of pounds with red lead, phosphorus, arsenic, and 
 
APPENDIX. 175 
 
 other ineffectual poisons, we cannot express much surprise that to 
 the complaints of naval officers of the fouling and corrosion of their 
 ships, the incasing of our gigantic iron-clads in outer wooden 
 copper-sheathed skins should be the expensive relief afforded by 
 the" Admiralty, and that Hay's composition and other so-called 
 anti-corrosive and anti-fouling paints should be in official favour. 
 
 " There is but one way of effectually preserving iron ships, which 
 is by sheathing them with zinc in the same way as formerly wooden 
 vessels were sheathed with copper, and as the plan proposed for 
 attaching the zinc plates to the hull has elicited a perfect means 
 of getting rid of the insecure butt joints in the construction of the 
 vessel, as well as rendering it easy to make the skin of the ship 
 flush and fair from top to bottom, and end to end. I have for 
 these reasons proposed to consider the practical construction of 
 iron ships in connection with the main object of this paper, namely, 
 the prevention of the iron hull from corrosion and fouling, by an 
 external sheathing of zinc plates. 
 
 " No one of even the slightest experience of iron ships can fail 
 to be aware of the extent of the corrosion and fouling to which they 
 are liable. But of what takes place ordinarily, no notice finds its 
 way into the columns of the newspapers ; and it is only of excep- 
 tional cases, where size makes the particular vessel remarkable, 
 such as in the case of the ' Great Eastern,' or where the matter 
 commands attention on account of its national importance, as in 
 the case of some of our formidable iron-clads, that any reports come 
 before the general public The matters of corrosion and fouling 
 are not, however, the less serious that they are permitted to pro- 
 ceed unhindered and on a most gigantic scale in silence. 
 
 " We have first to do with corrosion. The corrosion to which 
 iron ships are subjected is the oxidation of the metal. "Wooden 
 ships were liable to perforation by sea- worms, and to fouling by 
 sea-weeds and barnacles. After a time it was found that copper 
 attached to. a wooden ship's bottom would keep perfectly bright 
 and clean. The use of copper sheathing was first adopted by the 
 Admiralty in 1761, under the prevailing idea that its poisonous 
 influence would be obnoxious to marine vegetation and life, and 
 when H.M.S. 'Alarm ' was found clean after a four years' voyage, 
 the success was attributed solely to its poisonous character. The 
 reign of copper at the Admiralty has lasted from that date to the 
 present hour. But copper dare not be put on an iron hull. "What 
 was bad before in the extent of the corrosion becomes infinitely 
 worse under the influence of the galvanic action set up by the con- 
 tact of these two metals. 
 
 " In the early days of the sheathing of wooden ships it was found 
 that iron bolts in the timbers, and other objects of that metal in 
 contact with the copper, were eaten away incredibly quickly ; and 
 
176 APPENDIX. 
 
 in various accidental ways injuries of a like and very. serious nature 
 have repeatedly happened from the contact of copper with the 
 hulls of iron ships. Indeed, it is admitted upon all hands that 
 copper sheathing cannot be applied to iron ships, and that if it 
 were, the total destruction of the hull would be accomplished at 
 the most rapid rate ; nevertheless, as copper prevented the fouling 
 of wooden ships, there has been from the commencement of the 
 era of iron ship-building a too general and very fallacious hanker- 
 ing for some method of covering iron ships with copper. Various 
 compositions of india rubber, felt, and other insulating materials 
 have been interposed, in various cases, between the copper and the 
 iron skins of certain vessels ; and even at this moment under the 
 persistent tradition of the ' Alarm,' or the commercial influence of 
 Muntz's metal in official quarters, the Admiralty are having some 
 of our huge and costly iron-clads entirely coated below the water- 
 line with a jacket of timber several inches in thickness, in order to 
 insulate that copper sheathing which the wise men of a century 
 since very properly adopted for the preservation of the ships of 
 their day, but which it is surely inexcusable for the men in high 
 places now to put at a dangerous risk upon the hulls of the most 
 costly vessels ever sent upon the seas, when another and cheaper 
 metal, bearing exactly similar relations to the iron which copper 
 did to the wood, could be more simply and more easily applied. 
 It is not possible to ensure the insulation of the copper sheathing 
 from the iron hull of a vessel afloat. Even admitting that the in- 
 sulation can be perfected when the ship is sent out of dock, the 
 many casualties ' she is subjected to on her voyage are constantly 
 tending to injure and destroy the insulation. Grazes and rubbings 
 against piers and quays are always liable to make holes in and to 
 strip portions of the sheathing, whilst plates of the covering 
 metal may be peeled in various ways upon the open sea, and, once 
 contact permitted, nature will not be slow in putting galvanic 
 currents destructively in action. Even when an iron ship is actu- 
 ally encased in double planking, the shrinkage of the wood or the 
 opening of the joints by strains of the vessel's motion by permitting 
 the percolation of sea-water will give a connection between the two 
 dissimilar metals of the hull and the sheathing, and the iron of the 
 armour and skin will yield not the less quickly, not the less cer- 
 tainly, not the less dangerously, that it is hidden from the eye- 
 sight, or be the less expensive or difficult to repair, that several 
 inches thick of timber have to be removed from the exterior of the 
 ship before the extent of the injuries can be ascertained. One 
 example of the effect of copper on an iron ship is as sufficient for 
 practical illustration as a thousand, if there be a thousand similar 
 facts existent to back it up ; and if facts upon this point be desired 
 there would be no risk in engaging to produce a volume. We take 
 
APPENDIX. 177 
 
 one^~^ -'ears since, that comes readiest to hand. It is from 
 
 the ' HeifefSiw Times,' of 14th November, 1863. Truth is often 
 spoken of as deep in a well, and rare fragments of honest truth are 
 often to be culled from provincial ne\f spapers : 
 
 " ' Here is the last little piece of news from the iron squadron. 
 As lately as May in the present year there lay at her moorings off 
 Folly Point, in the Medway, the youngest of these Titans — the 
 " Royal Oak." Of enormous tonnage, giant proportions, and hull 
 that seemed to make the tired ocean groan under her, she was 
 pointed out with pride by yachtsmen and passengers as a " bran- 
 new bulwark of England." Towards the close of May she got 
 under weigh a maiden ship, "ataunto," "spick and ]span," as hand- 
 some as paint and varnish could make her, to join the Channel 
 fleet in its cruise round England. She turned out a capital sea- 
 boat ; she showed her heels to the best of the squadron before the 
 wind; and more than once had to lower her topsails to let the 
 laggards in her wake overhaul her. She was " another success,^' 
 and the Admiralty were as proud of her as the people. Now she 
 comes into port, and what do we hear ? That smooth and burnished 
 bottom, coated with " Muntz's metal " — thanks to which she made 
 such fine sailing — has put her hors de combat far sooner than 
 fighting could have done. This ship — this Admiralty pet — which 
 has been just four months in commission, is as rotten already, as a 
 collier after forty seasons. They have got her into dock, and they 
 find that all along the line between her sheathing and her lower 
 plating, the great and costly iron slabs have perished into some- 
 thing like plumbago. There are holes three quarters of an inch 
 deep, in just that very part of her armour which protects the 
 '' wind-and- water line." Where the hooks of the side-ladder have 
 helped the sea- water and the sheathing to do their work, the iron 
 4s gone in a deep furrow, and from all the joints of the submerged 
 plates there oozes a black slimy liquor, which is doubtless chloride 
 of iron, and which means that plate and rivet and backing are rot- 
 ting altogether, inside and out of sight. Into some of the four-and- 
 a-half-inch plates, which were to guard this bran-new vessel, you 
 may poke a penknife blade half way to the handle, in spite of an 
 ingenious band of some sort of metal, not intelligible to those who 
 made the discovery we are describing, the effect of which was to 
 obviate galvanic action. In a word, as we have said, the maiden 
 monster has come into dock rotten from her first trip.' 
 
 " This is the account of the effects of copper, sheathing three 
 years ago, and yet during the present spring the costly 'Nor- 
 thumberland' has sailed from Chatham for Devonportto be covered 
 with the same destructive metal, and the huge ship, whose launch 
 was so ruinous a labour, may come perhaps, after a brief life of 
 rapid consumption, to an inglorious if not cataclysmal end. How, 
 
 12 
 
178 APPENDIX. 
 
 it will be properly asked, is it proposed to overcome this evil. The 
 corrosion of iron ships may be effectively stayed by the use of zinc 
 sheathing. The zinc sheathing may be put direct upon the iron 
 skin, and the iron will not only not be injured, but it will be pre- 
 served. The idea which has been practically worked out by Mr. 
 Daft, in his well-considered plan of zinc sheathing, is this : — If the 
 galvanic action set up in the cell formed by the iron ship and the 
 covering of sheet copper — or Muntz's metal, which is a compound 
 of copper — be destructive of the iron of the vessel, then to use, as 
 a means of preservation, that metal to which iron will stand in the 
 voltaic circuit, as the copper in the former case did to the iron. In 
 other words, if the ship and her sheathing form a voltaic battery, 
 the elements of which stand in such electro-chemical relation to 
 each other that the ship shall be destroyed, then to find out the 
 way to reverse the conditions of that battery, so that the ship shall 
 be preserved. This is done by the substitution of the element zinc 
 for the element copper. 
 
 " That we may not appear to be pinning our faith quite upon 
 Mr. Daft's intellectual sleeve, we will quote a few passages from 
 Mr. Lamport's paper, " On Wood and Iron Ships," in vol. iv of 
 the ' Transactions of the Institute of Naval Architects.' He pro- 
 ceeds thus : 
 
 " ' First. — When chemical decomposition is produced upon two 
 metals in contact, the more oxidizable one becomes electro-positive, 
 and the less oxidizable one electro-negative. The various metals 
 in common use may be arranged in a series, in which those first in 
 order become positive by contact with all those that follow, and 
 negative with those that precede — as zinc, iron, lead, tin, copper, 
 silver, gold, platinum. 
 
 " ' Secondly. — When any two of the above metals are combined 
 in a fluid capable of acting upon one of them by chemical decom- 
 position, a galvanic current is produced, passing from the more to 
 the less positive metal, which then becomes negative. The energy 
 of the current is in proportion to the vitality of the chemical 
 action, which is confined to the metal which is most electro- 
 positive. The other, becoming negative, is protected from the 
 chemical action. For example, if iron and copper be combined in 
 an acid or in sea water, iron, being more electro-positive than 
 copper, is chemically decomposed, or, to use a more common 
 phrase, is " corroded." The galvanic current, passing from the 
 iron or generating metal to the copper as the receiving metal, 
 changes the condition of the latter from a naturally electro- 
 positive condition to one relatively negative. The metal, thus 
 rendered electro-negative by the galvanic current, becomes proof 
 against the action of the fluid as a chemical agent. No decompo- 
 sition takes place, and it assumes the condition of a "protected" 
 
APPENDIX. 179 
 
 metal, while the more positive one is still more rapidly eaten into 
 and decomposed by the stimulated chemical action. If ia place of 
 copper and iron we take iron and zinc, the same process takes 
 place, reversed, however, as regards the iron. Zinc, being more 
 positive, is chemically decomposed, and the current passing to the 
 iron renders it negative, and consequently insoluble or "pro- 
 tected." It will, therefore, be observed that it is the chemical 
 action that is deleterious, and that the ensuing galvanic current, 
 by changing the natural condition of the least positive of the 
 metals to that of a negative receiver, protects it from the chemical 
 decomposition to which alone it would have been subjected. 
 Further, the union of three or more metals produces similar 
 results— as with copper, iron, and zinc. The corrosion takes 
 place in the most electro-positive, zinc, to the protection of the 
 other two. 
 
 " ' Thirdly. — To produce these phenomena actual contact is not 
 necessary, as the fluid itself becomes a medium of combination. 
 
 " ' Fourthly. — The relative size of the positive and negative 
 metals has no influence upon the direction of the current, which 
 passes always from the most electro-positive metal to the other, 
 irrespective of surface or mass. A small piece of metal, there- 
 fore, may absolutely protect a far larger mass of one rendered 
 electro-negative. A considerable preservative efifect has been 
 observed when the surface of zinc has been to that of copper as 
 1 to 1000.' 
 
 " The relationship of zinc to iron in a galvanic cell is un- 
 doubted; indeed, it may be and was proved by the first voltaic 
 battery recorded, namely, that formed by simply placing two 
 plates of the metals, with their lower edges touching like a V, in 
 a glass of salt and water, or diluted sulphuric acid. This experi- 
 ment may be performed by any one with pieces of zinc and iron 
 and copper and iron respectively coupled in two ordinary tumblers 
 filled with salt and water. The solution in the one wUl be colour- 
 • less, that in the other quickly stained of a deep blood-red hue with 
 the oxide of iron, which will be also deposited in quantity at the 
 bottom of the glass in the condition of ochre. The iron in the 
 other cell will keep for weeks and months perfectly unattacked, 
 whilst the zinc in connection with it will remain bright and clean, 
 from gradually and continually losing a small portion of its volume, 
 a very slight quantity of the white oxide of zinc being deposited in 
 the tumbler. 
 
 " Zinc sheathing applied to wooden vessels does not answer ; 
 for when zinc is isolated on wood, it becomes its own protector. 
 The zinc oxidizes, and the hard oxide which results soon covers 
 the surface, and exfoliates so slowly and irregularly that fouling 
 takes place to a considerable extent. Copper, on the contrary. 
 
180 APPENDIX. 
 
 ■when thus isolated on wood, suflfers sufficient chemical degradation 
 to present a constantly clean surface. What the zinc requires to 
 compete with the copper for brightness and cleanliness is a little 
 stimulus J and this accelerated action is effectively provided for by 
 the galvanic current set up by its contact with iron. Thus, the 
 one thing needed to make zinc sheathing a success is involved in 
 that desideratum so long necessary for iron ships — the prevention 
 of their corrosion and fouling by the direct application of a metal 
 ■sheathing. If the expensive sheathing with copper be so repeatedly 
 and persistently attempted, the greater cheapness of zinc cannot 
 be any valid objection to that metal; and this corrosion and 
 fouling can be prevented by zinc sheathing, and that, too, with 
 the additional vital advantage that it will at the same time ensure 
 the most perfect preservation of the ship. We have in zinc 
 exactly what is required — a metal that may be put direct, without 
 any insulating material whatever, upon the bare surface of the 
 iron skin of the ship — that when so placed will form a voltaic cell, 
 the electro-chemical action of which will preserve the iron, while 
 the zinc will only sufficiently and regularly degrade and exfoliate 
 to maintain a clean surface in any waters, at the same time that 
 it is capable of enduring for four or five years without removal. 
 
 " I come now to the second point — fouling. This, like corrosion, 
 or dangerous defects of construction, is not the less serious and 
 expensive that it is kept out of the arena of general discussion. 
 It is not to the advantage of shipowners to make any fuss about 
 what they know not how to prevent, or to mention any scheme 
 which has any probability of doing that which they think will 
 seriously diminish, if not entirely ruin, their business. The fouling 
 of Government ships, too, not only involves loss of speed, but 
 more steam-fuel, more food and provisions, longer pay for the 
 crews, and expensive docking and repairs, necessitating the labours 
 of hundreds of men, often for considerable periods of time. I 
 myself saw, a few months since, at one of our principal naval 
 yards, employed for the best part of a day upon one of our large 
 iron-clads, in bringing her into dock and shoring her in position, 
 upwards of three hundred men. But as nobody but the public 
 has to pay the expenses of fouling, and bringing grist as it does to 
 the official mill, it is not at all likely to receive correction so long 
 as that bountiful paymaster, the nation, takes no heed whatever of 
 the matter. 
 
 " That the fouling of iron ships is a most serious detriment and 
 a continual exorbitant expense, the very fact that copper sheathing 
 is so persistently attempted, in spite of all obstacles and dangers, 
 is collateral evidence of the very strongest kind ; and, indeed, no 
 shipowner or captain of any experience, if put to the test of his 
 veracity, could deny it, however unwilling he might be, from 
 
APPENDIX. 181 
 
 what he probably, but very erroneously, would consider prudential 
 motives, to admit the truth of the assertion. On this.,, point, 
 however, as on others, I intend to take evidence, and from the 
 abundance of witnesses I will now select to bring Mr. Lamport 
 into court. In vol. ix of the ' Transactions of Naval Architects ' 
 he admits that the cost of copper is not the reason why iron ships 
 are not sheathed with that metal. At page 289 he says — 
 
 " ' The next section takes in the doubtful qualities of iron, and 
 the first is that of superior economy of maintenance and repara- 
 tion. I admit that iron ships do not incur the periodical cost oi 
 coppering. But why? Certainly not because the outlay is not 
 needed, but because owners are compelled to forego its admitted 
 advantages. Chemical action forbids the contact of copper or 
 yellow metal sheathing with iron ; but I put it to any owner of an 
 iron ship whether he would not Willingly pay the cost of coppering 
 to avoid the drawbacks of fouling. If so, can the constrained 
 saving be considered in the light of a gain ? Its result is a foul 
 bottom and a lengthened and uncertain voyage; and, as time is 
 money, such saving is anything but economy. But is there no 
 counterbalancing outlay from scraping, painting, or otherwise 
 coating iron ships' bottoms, and is there no loss of material from 
 oxidation of the iron itself to set against the caulking and coppering 
 of wooden ships ? 
 
 " ' By Lloyd's rules, the thickness of the plates for twelve years' 
 iron ships is -i- inch more than those of the six years' grade. The 
 experience of the committee, therefore, points to J- inch as the 
 waste due to six years' wear and tear. In six years a twelve years' 
 vessel will be liable to be reduced, we may suppose, to the condi- 
 tion of a six years' ship, and a six years' vessel in this period may 
 be supposed to be reduced to a condition to which no class what- 
 ever would be assigned. Making every allowance for excess of 
 caution, enough remains to show that the annual depreciation of 
 the iron plates is considerable j and this, added to the cost of 
 frequent docking, scraping, and painting, cannot leave much dif- 
 ference between the annual expense of maintenance of wood and 
 iron ships.' 
 
 " Neither is the additional cost of steam-power required to pro- 
 duce an inferior degree of speed in the ship by any means a trifling 
 consideration when the class of the vessel is one of large dimen- 
 sions and horse-power. Upon this point I will put another reliable 
 witness into the box, again making the selection from the Institute 
 of Naval Architects. At the meeting of 28th February, 1861, 
 Admiral Halsted spoke these words : — ' Now I come to another 
 terrible business, and one in which I hope my colleagues in this 
 institution will take a leading part. Here is the " Warrior," with 
 her 1250 nominal horse-power engines, to go fourteen knots an 
 
183 APPENDIX. 
 
 hour. Bnt pray for how long? How many will elapse at sea 
 before the fouling of her bottom will reduce her fourteen knots to 
 twelve^ and even below that ? As everybody here knows, perhaps 
 better than myself, the fouling of the bottom of iron ships is a 
 question connected^ and closely connected, with the nature of the 
 material itself; but I think it is not generally understood that it 
 is not a mere question of the difiBculty of preventing the corrosion 
 of the bottoms of iron ships. There are a dozen ways by which 
 actual corrosion of the metal may be prevented, but the misfortune 
 is that all these appliances have the effect of presenting such an 
 enticing surface to marine substances and animals that they carry 
 on their little operations till there is no end of them, and in six 
 months the surface of the bottom of your ship is destroyed, in a 
 great measure, for all purposes of speed. It is wonderful, the 
 money which has been paid away in this country on that account. 
 We possess some 600 iron screw-ships, and there is not one of them 
 but is subjected to this difficulty at least twice a year. And it is 
 not the mere expense of hauling into dock, cleaning the bottom, 
 and re-painting ; but it is the number of steam horses that have to 
 be fed to their fullest extent constantly, although the effect pro- 
 duced by their efforts is gradually diminishing. Neither is it that 
 the steam horses cannot take their amount of food ; on the con- 
 trary, the tendency is rather to overfeed them at such times, so 
 that the reduced speed has no compensating economy, but the 
 whole effect is direct loss. What, then, should prevent the council 
 of such an institution as this submitting that some definite means 
 should be taken to overcome this disreputable fact, which has ex- 
 posed us to so much public loss up to the present day ? There are 
 men of talent in the country who can discover a remedy, or who, at 
 all events, can show us that it cannot be done, and then we may 
 find out some substitute in place of a remedy. I attribute our 
 neglect of this point entirely to the fact of the Government con- 
 demnation of iron ships hitherto as being unfit for the purposes of 
 war. Had it not been for that most unjust and impolitic condem- 
 nation, I believe a remedy, or a substitute, would, as a great 
 national object, have been provided long ago.' 
 
 "Two explanations are necessary to give full effect to the 
 meaning of this speech. In the first place we must bring again to 
 mind that the then apparently incurable disadvantages of the 
 corrosion and fouling of iron ships had so alarmed the Admiralty 
 in 1847 that the sale of the iron ships in our naval service was 
 actually commenced. The persuasive eloquence of the projectors 
 of anti-fouling and anti-corrosive compositions, however, had a 
 happy influence upon the fate of the British iron navy, and the 
 recalling of that desponding fiat is really the only good that ever 
 has been — and in all human probability ever will be — effected by 
 
APPENDIX. 183 
 
 those senseless and fallacious nostrums. In the second place, we 
 should observe that when copper is put upon and in connection 
 with iron in sea-water, not only is the waste of the iron terrifically 
 increased, but the copper itself, on the other hand, becomes totally 
 inoperative and entirely ineffective. It no longer degrades ; it is 
 electro-chemically preserved. It no longer maintains, as it would 
 do upon wood, a clean surface ; exfoliation no longer takes place, 
 and in proportion as the superficial area of the iron approaches that 
 of the copper so will the latter be more and more coated with 
 thicker and thicker deposits of the carbonate of lime and magnesia 
 abstracted from the sea-water, until the whole of its anti-fouling 
 character is lost and the ship might be but an encrusted rock, 
 covered with luxuriant fields of seaweeds and adherent mollusca 
 floating upside down. 
 
 " This fouling is exceedingly expensive at all times, but it would 
 be particularly perilous and vexatious in that of war, to be obliged 
 constantly at short intervals to send our large transport and iron- 
 clad ships into dock for cleaning alone ; the retardation of the 
 speed, too, of such vessels whilst at sea is a most serious item, not 
 only in regard to their effectiveness when in pursuit of, but when 
 brought into hostile collision with the enemy. Even in money 
 expenditure it involves a really reprehensible waste. In respect to 
 the mere operation of cleaning, it is notorious that many of our 
 wealthiest shipowners and some of our finest commercial companies 
 prefer to let their vessels run considerably fouled rather than incur 
 too frequently the expensive operations of cleaning and scraping 
 in dock. It may be also said that the merchant shipowner experi- 
 ences an additional loss ia the laying by of his ship, for it is the 
 most active employment of his vessel that produces the most 
 profitable result. 
 
 ''Again, the immense size of our iron-clads would render delays 
 in getting into dock on account of insuflSciency of tides, constant 
 occurrences, while similar delays would also happen in respect to 
 their liberation. Long and dangerous absences would thus be 
 common amongst the vessels of our fleets ; and more than possibly 
 at the very time when our utmost naval strength would be wanted, 
 half our vessels might be away, either in dock cleaning, or return- 
 ing home for that purpose, or on the voyage out again after the 
 operation had been performed. Let us, however, look for a 
 moment, as closely as the little light that has been permitted to be 
 shed on the subject wiU allow, at the money cost involved by this 
 fouling. 
 
 " The ' Diadem,' 800 nominal horse-power, burns sixty tons of 
 coals a day, and does nine knots per ton burnt. Now, if the loss from 
 fouling amounted to one knot per ton burnt, the waste per day of 
 steam fuel would be iE14, adding to which tlie extra cost of 
 
184 APPENDIX. 
 
 wages for the loss of time on a long voyage or a naval cruise, and 
 other items, would bring the loss to something like £25 a day. 
 Again, if the ' Warrior,' 1250 horse-power, and burning not less 
 than 100 tons of coal a day, should lose two knots an hour, or one 
 seventh of her speed, by fouling, the utterly wasted cost of this 
 deterioration of speed — for be it remembered the full quantity ot 
 combustion that would give the highest speed with a clean bottom 
 is required to attain with a foul hull this lower rate — would be, 
 supposing English coal were used, £30 a day ; and if fuel had to 
 be bought at foreign stations — a most probable and frequent 
 necessity — this expense would range from any increase up to more 
 than double. When to this cost of fuel we add wages and other 
 incidents we shall find that the estimate of £4>0 a day formed by 
 Admiral Halsted in 1861 of the money value of the loss in this 
 vessel is really within the mark, and entirely within the actual 
 expenditure. With thirty vessels afloat, and assuming the average 
 loss from each as £30 a day, the total waste for the whole fleet 
 would be £900 per diem, or £329,500 a year from this one source 
 of fouling alone. 
 
 " In the face of all these evils there is but one hope for the prac- 
 tical application of copper. It is the perfect insulation of the 
 sheathing from the ship. This is the point where Mr. Daft 
 began, and no man has been more successful than he has in 
 this direction. 
 
 '' In the year 1849, impressed with the importance of preventing 
 iron ships from fouling, and protecting them from corrosion, he 
 made his first step by coating the famous Muntz's metal with an 
 insulating material on one side, in order to prevent galvanic action 
 being set up when such metal was applied to the skin of an iron 
 ship. He succeeded at that time in firmly attaching sheets of pure 
 vulcanised india-rubber to sheets of yellow metal, and when the 
 coated sides of these sheets were placed against the hull, the yellow 
 metal was as perfectly insulated from the iron as it is possible to 
 insulate metals in sea-water. 
 
 "The extra care required in the workmanship, and the high 
 price of the copper, were circumstances tending much against the 
 system of insulated copper sheathing, however desirable it might 
 otherwise be. But the fatal objection was that, no matter what 
 might be the care, no matter how perfect the insulation, the con- 
 nection of the two metallic elements was ever liable to be made by 
 a variety of accidents ; indeed, even the overhanging of the anchors, 
 or of an iron chain, might be the medium of setting up destruc- 
 tive galvanic action in a fully sheathed ship. 
 
 "But there is a still more costly and even more fallacious attempted 
 avoidance of the difiBculty. I mean the faint-hearted compromise 
 between iron and wood. Iron ships are not kept clean at sea ; 
 
APPENDIX. 185 
 
 wooden ships^ copper sheathedj are. Therefore, say the compro- 
 misers, let us build ships with iron frames and wooden skins, that 
 we may nail the copper on their hulls. Composite ships are the 
 disgrace of the age ; they are a standing reproach because they are 
 sneaking confessions of failure and incompetence. Who that knows 
 the value of iron, that has taken action in, or even but watched, 
 its manufacture and its practical treatment in any of its multifa- 
 rious applications, but feels the same glowing pride in its stalwart 
 strength, its metallic muscle and fibre, its reliability and thorough 
 powers of endurance, as he does in his own birthright to the name 
 of Englishman, and but thinks all the higher of his countrymen 
 that they are unsurpassed as iron-workers. 
 
 " Convinced that the system of insulated copper sheathing was 
 and ever niustJbe imperfect, Mr. Daft turned his attention to 
 another metal — zinc, and at the same time set himself to over- 
 come the mfficulties which had been experienced in attaching the 
 copper plates to the iron hull. Cement and all sorts of adhesive 
 compounds had turned out complete failures, and nothing but the 
 old plan of nailing the sheathing on, as it was done upon wooden 
 ships, seemed likely to answer. 
 
 " To make an iron ship, and then to cover it over thickly with 
 wood — to put, in fact, the iron ship inside of a wooden one — 
 seemed to him, as it must still do to every competent person, a 
 most undesirable and unscientific procedure. Having by his ex- 
 periments convinced himself thoroughly of the value of zinc 
 sheathing, he devised the most simple and admirable plan for the 
 firm attachment of the plates that could possibly be desired, and in 
 doing this he has made the most important improvement in the 
 construction of the iron ship itself. The butt joint was the weak 
 part of the ship ; Mr. Daft wanted a groove round every one of the 
 skin plates which he could fill with wood, as the medium to which 
 to nail his zinc sheathing plates, and in getting his groove he got 
 rid of the butt joint. But of this, hereafter; for the present we 
 have to deal with zinc. 
 
 " With zinc sheathing we have the following advantages : — It is 
 one third the price of copper or yellow metal ; it requires no insu- 
 lating material, nor anything whatever interposed between it and 
 the iron skin of the ship ; it electro-chemically protects the iron, 
 and is itself degraded and imperceptibly peeled away by the same 
 electro-chemical action ; it keeps perfectly bright and clean, and is 
 as durable as copper or Muntz's metal. 
 
 " Of these assertions some proof will naturally and properly be 
 asked. Cabinet experiments might be possibly deemed not suflS- 
 ciently practical upon such an occasion as the present, however 
 interesting and instructive. I bring forward, therefore, the results 
 of actual trials of the system made by the Government. 
 
186 APPENDIX. 
 
 " After proving the value of zinc as a sheathing for iron in sea- 
 water, in conjunction with the ' Special Committee on Iron/ in 
 1863 and 1864, Mr. Daft received instructions from the Lords 
 Commissioners of the Admiralty, on the 18th February, 1865, to 
 visit Portsmouth Yard, in order to see that certain experiments 
 with two plates upon his plan were satisfactorily made for testing 
 the eificacy of zinc sheathing for iron ships. 
 
 " Two plates were made up of 4 inch plating, with -f- straps at 
 the back or inside, so as to represent the actual plating of a vessel 
 of some 3000 or 4000 tons, and grooves^ according to Mr. Daft's 
 patent, were left, of f inch wide, between the edges of the plates; 
 these grooves were subsequently filled in with teak strips, and the 
 surface made fair and flush. The plates were encased in teak 
 frames and backs, made waterproof, so that they (the plates) should 
 have their faces or outsides only exposed, as in the case of an actual 
 vessel. Mr. Daft's original intention was to nail on the zinc 
 sheathing directly against the bare iron, in order that the contact 
 between the zinc and iron should be perfect, and that the neces- 
 sary amount of electro-galvanic action should be set up when the 
 plates were lowered into the water to keep the zinc exfoliating or 
 peeling away at a rate which would keep them clean and bright ; 
 but by instruction the iron was coated all over with a composition 
 in fashionable use in Her Majesty's dockyards — Mr. Hay's glue — 
 and contact had therefore to be established by using nails for 
 fastening on the sheathing, long enough to go through the teak- 
 caulking in the grooves, and to turn against the iron at the back of 
 it. A few iron nails — common clouts — were introduced, in order 
 to establish firmer and more enduring contact, and to prove that 
 they might be used, if not to advantage, certainly without detri- 
 ment to the work. 
 
 "The unfortunate interposition of an insulating substance 
 between the zinc and the iron would have rendered the former 
 liable, but for the action established by the long nails, to foul to a 
 certain extent. In fact, the insulation directed would, if it had not 
 been practically subverted by this means, have produced in the 
 experiment results parallel with the case when zinc is used for 
 sheathing wooden vessels. This test was a source of anxiety to Mr. 
 Daft, which was only dispelled when, on the 12th October, 1865, 
 the plates were raised for preliminary examination (as they were 
 to be twelve months under water for the trial). At this examina- 
 tion, after six months' immersion, they were found perfectly clean, 
 though not bright, as would have been the case had the chemical 
 action not been checked by insulation. The zinc had not wasted 
 enough. An ounce per foot per annum — the rate at which it had 
 been disappearing — was not sufficient to ensure a bright surface, a 
 bright metallic surface being, that of all others the most to be 
 
APPENDIX. 187 
 
 desired for obtaining speed in iron ships or wooden vessels. This 
 fact, that the zinc could be kept perfectly bright, having been 
 thoroughly established previously by Mr. Daft, induced him to 
 cause a third experiment to be made at Portsmouth. 
 
 " At the end of the year of trial a correspondence took place 
 between Mr. Daft and the Admiralty as to raising again the two 
 plates ; but, as summer was approaching, it was suggested by the 
 Admiralty that they had better remain three months longer. 
 They were thus doomed to go through another season for the rapid 
 growth of weeds and barnacles, which, as any naturalist will quickly 
 perceive, was subjecting them practically to another year's trial, by 
 including two spawning seasons of the barnacles and molluscous 
 animals, and two seasons of the fertilising periods of the seaweeds, 
 giving the plates, in fact, a double chance of fouling. This sugges- 
 tion was, however, readily agreed to by the inventor; and when 
 they were taken up for the inspection of the Lords Commissioners 
 of the Admiralty, on the 12th' of August, they were found still in 
 a state of the most perfect cleanliness, though, as before, not bright. 
 About the frame, and on the iron chains in which the plates were 
 swung, were immense quantities of barnacles and weeds, but not 
 a vestige on the plates. Mr. Daft then suggested that one or both 
 plates should be stripped, and everything — zinc, nails, teak, iron, 
 &c. — thoroughly overhauled, and an accurate account taken of the 
 loss of the zinc ; and this was, he believes, with respect to one 
 plate, accordingly done. Not that the 'authorities' have furnished 
 him with particulars, but, having asked for that favour, he is in 
 hopes of getting them. However, it may be asserted, without fear 
 of contradiction, that the zinc had lost only at the rate of exactly 
 one ounce per foot per annum. It would be better that it should 
 lose double that quantity. 
 
 "One ounce per foot per annum is not much more than zinc 
 sheathing loses on wooden ships, where a very feeble galvanic 
 action indeed exists, and possibly at times none at all, when fouling 
 more or less occurs. Not, as we have already stated, that fouling 
 is peculiar to zinc alone, for other sheathings — copper and yellow 
 metal — foul to the same extent as iron or zinc, or any other metal, 
 when their condition is made negative in an electro-chemical sense. 
 If, for example, contact with iron and copper and yellow metal be 
 made in sea-water, then yellow metal and copper will foul rapidly 
 at the expense of the certain destruction of the iron — the positive 
 metal. Mr. Daft thinks that in order to wear out the old wooden 
 ships with as little expense as possible, and yet keep them useful 
 and safe as long as they could be, it would be wise to use iron 
 nails and zinc sheathing, for the zinc would preserve the iron 
 fastenings about the vessels, and the clouts (iron nails) in the 
 sheathing would hold the zinc on longer than zinc nails, and 
 
188 APPENDIX. 
 
 materially aid in keeping it clean by increasing its exfoliating 
 qualities. Zinc for -wooden ships under this treatment would be- 
 come equal to copper or yellow metal for cleanliness, would last 
 quite as long, and would cost no more than one third the price. 
 
 " To ensure a thoroughly clean surface, the 'peeling away' should 
 go on at a rate of not less than 2 oz. per square foot per annum. 
 At that rate it is kept absolutely bright, and may be still further 
 increased to 2-^ oz. by leaving certain parts of the hull unsheathed 
 — for example, the keel, stem and stern posts, &c. — for by exposing 
 a greater proportion of iron than zinc (within certain limits) the 
 zinc is more rapidly destroyed, while, as I have in another place 
 shown, the uncoated iron is, notwithstanding the immediate 
 absence of zinc, kept free from fouling for some reason that at 
 present I fail to perceive. 
 
 " An exceedingly useful feature is the power that is possessed 
 within certain limits of thus modifying the electro-chemical action 
 on the zinc. There is a definite relationship between the extents 
 of the surfaces of the iron and the zinc, and the rate of the 
 exfoliation is in exact proportion to the areas of the two metals. 
 The electro -chemical action can therefore be modified, accelerated, 
 or retarded, according to requirement, by the proportion of the 
 ship that is sheathed, or by internal plates in connection with the 
 bilge-water. Thus, sheath one quarter of the iron, you give half 
 the superficies of zinc to iron, and in this state, when immersed, 
 the destruction of the zinc is at a medium point, and the iron is 
 perfectly protected. Now reduce the sheathing to ith = ith of 
 the surface, and -you increase the destruction of the zinc, but the 
 iron is still fully protected ; still further reduce the zinc to say 
 ■jij-th = ith the surface of iron, and you arrive at the maximum 
 destruction of zinc. Go further in this direction, and you do not 
 increase the destruction of zinc, but you enfeeble the protection of 
 the iron. 
 
 " Entirely cover a surface of iron with zinc ; you then have two 
 to one of iron; in this state the exfoliation of zinc is feeble, but 
 quite enough to keep it bright in sea-waters. The iron when com- 
 pletely covered is, of course, fully protected by the electro- galvanic 
 action exerted upon the zinc, and, in fact, a singular proof of this 
 has just occurred in the Admiralty specimens inspected by the 
 Lords at Portsmouth. A plate, grooved and caulked with teak, 
 about 2 ft. 1 in. by 1 ft. 4 in., was partly plated with zinc, in order 
 to try the comparative results, and a margin of bare iron, about 
 3 in. wide, was left around the sheet of zinc. This specimen had 
 been under water about ten months; the zinc was beautifully 
 bright and clean ; the margin of iron was only coated with a little 
 slime, which, upon being rubbed off by the finger, discovered a bright 
 clean surface ; the wood frame about this specimen, which had been 
 
APPENDIX. 189 
 
 fixed to it for lowering it into the water, was an enormous mass of 
 polypi, barnacles, and weed, thus proving that the zinc had a protect- 
 ing effect to some distance beyond the actual surface covered by it. 
 
 " The moment we come, with a proper knowledge of the natural 
 history of the subject, to investigate the nature and character of 
 fouling, and what should properly be its most perfect prevention, 
 we come decisively to the unalterable conviction that all anti- 
 corrosive and anti-fouling paints can never be any more than the 
 merest nostrums. Barnacles do not feed with their feet j oysters 
 do not imbibe nutriment through their shells; mussels derive no 
 vital sustenance through the cords of the byssus by which they 
 moor themselves. Seaweeds are not like land plants, which take 
 up their supporting fluids by the fibres of their roots. The ' root ' 
 of a seaweed is no more than the mere disc of attachment, the 
 leather ' sucker ' which holds it to the rock or to the side of the 
 ship. The idea, therefore, of poisonous compounds for painting a 
 ship, with the view to killing the barnacles, shell- fish, and seaweed, 
 is to the mind of a naturalist much on a par with a project for 
 poisoning a man through the sole of his boot. The individual who 
 should propose to smear the groimd with phosphorus and arsenic 
 to destroy an invading enemy would be sent to Bedlam, but the 
 quack who offers arsenical and phosphoric soaps for ships' bottoms 
 sells his wares and injures no one but his customers. 
 
 " There is another view to be taken of the natural history of 
 shell-fish and seaweeds. All the things that attach themselves to 
 a floating ship only stick to it, and the proper cure therefore is 
 never to leave them any surface to stick to. Why copper on a 
 wooden ship keeps clean is because it never has a permanent 
 surface, and it is evident nothing can long adhere to a surface that 
 is always dissolving away. Now, it is only in the young state that 
 either marine organisms or vegetation have the power of attach- 
 ment to foreign bodies. Pull an oyster from its bed, or a seaweed 
 from its rock, and neither is ever a fixture anywhere again. If, 
 then, the minute young only of shell-fish and the minute seeds 
 only of seaweeds possess either free or involuntary locomotion, it 
 is clear they can only adhere to very minute portions of any solid 
 surface, and, therefore, as the extent of their adherence is not 
 larger than the exposed surface of a metallic particle, it is evident 
 that the exfoliation of that particle will carry away with it the 
 minute organism attached ; and it is also as evident that as that 
 organism has only once in its life the power of attaching itself, its 
 capacity of individually contributing to the fouling of any ship is 
 gone for ever. The exfoliation of the metal of a ship must, there- 
 fore, be constantly going on. The voyages which the vessel un- 
 dertakes will take her from winter in one latitude to spring time 
 and spawning and seeding season in another; and wherever and 
 
190 APPENDIX. 
 
 whenever the myriads of young moUusca, cirrhipedes, serpulse, 
 corallines, bryozoa, and teredines, swarm in the sea, then and there 
 will they seize upon every bit of the vessel within their reach, and 
 so long as the surface of the hull remains will go on growing and 
 prospering to the serious detriment of the progress of the ship. It 
 is equally evident, under this aspect of the case, that fouling can 
 never be prevented by any vitreous or glazed substances attached 
 to the hulls of ships. However smooth or polished, however 
 slippery any absolute solid permanent surface may be supposed to 
 be, young barnacles, oysters, mussels, take too good a hold upon 
 it, and the little floating seeds of seaweeds stick too close to it ever 
 to slip oflF, and can only be got quit of by being 'slipped away 
 with' by the flaking of the surface itself. 
 
 "Needless as any proof on this subject would thus appear to 
 be, it is, nevertheless, imperative to put in an example or two of 
 actual results of anti-fouling paints. These results are of two 
 distinct characters. One, the efi"ects produced in respect to the 
 fouling of the hull ; the other, the efiects produced upon the iron, 
 for many of these anti-fouling and anti-corrosive compositions are 
 by no means innocuous to the constructive material of the ship. 
 I really am very sorry to select ' Hay's anti-fotding paint ' as an 
 illustration, because Mr. Hay is the Admiralty chemist, and his 
 ' composition ' is under the immediate patronage of the Admiralty. 
 But I take it because it should be, from the recognition it has re- 
 ceived, presumably the best of its class ; and because, if I did not 
 take it, I should hereafter most probably be accused of having 
 insidiously picked some inferior example, designedly leaving out 
 the very one I ought to have brought forward in justice to the 
 anti-fouling painters. I quote from the ' Times ' of 18th November, 
 1864 — not an unfriendly organ towards the dockyard oflficials : 
 
 " ' Notwithstanding the numerous descriptions of what are 
 termed "anti-fouling" mixtures, which have been submitted to 
 the Admiralty, no discovery appears as yet to have been made of 
 a preparation for efl'ectually preventing the accumulations of 
 animal and vegetable matter over the hulls of iron vessels. 
 
 " 'Although the bottom of the iron frigate "Achilles" was 
 coated over before her launch with the "anti-fouling" compo- 
 sition of Mr, Hay, the Admiralty chemist, so foul had the bottom 
 of this vessel become while lying in Chatham harbour, preparing 
 for sea, that in the run from Chatham to Devonport her speed fell 
 off more than three knots an hour from her steaming rate on the 
 occasion of her official trip at the Maplin Sands. 
 
 " ' When docked at Devonport the bottom of the " Achilles " 
 was not only foul, but many of the plates were left completely 
 bare of composition, while corrosion had in many cases eaten 
 away the plating to the depth of from -^th to tV^Ii of an inch.' 
 
APPENDIX. 19^ 
 
 " I can add my own testimony, having seen the ' Valiant ■" piit 
 into dock a short time ago, after sixteen months in harbour, thaw, 
 the condition of Mr. Hay's composition, or of the iron vessels 
 coated with it, has been in nowise improved j nor can I conscien- 
 tiously say one single word in favour of any other of the ' compo- 
 sitions,' anti-fouling or anti- corrosive, with which various portions 
 of that noble iron-clad was besmeared. Mr. Hay's compound has 
 a basis of copper, and the hull of the ' Valiant ' was deeply eaten 
 into by the galvanic action, as well as thickly and totally encrusted 
 with a bronze-coloured oxide. It certainly was not so foul as 
 some other portions of the ship, but it would not have been even 
 in a semi-clean state if it had not been 'hogged' by some new 
 patented scraping machine before the ship came into basin. 
 
 " Doubtless I should find I had left a hole in the armour of my 
 argument if I omitted to say a few words upon the other metallic 
 paints in which other metal bases are used — as red lead, quick- 
 silver, and zinc. I assert of all such, without fear of defeat — con- 
 tradiction on all points I know I may expect — that no paint having 
 the oxide or other salt of any metal can possibly be of any use in 
 the prevention of fouling; and not even if the absolute metal 
 itself in a pulverized state could be mixed in with the oil, varnish, 
 or other medium, would such a paint have any preventive influence. 
 Take zinc itself in fine powder, for example ; it would be utterly 
 useless, because each particle of the metal being encased in and 
 insulated by the medium of the paint, galvanic action would be 
 stayed, and there would be no exfoliation of the surface — the sole 
 means of avoiding marine foulness. In the cases of red lead, 
 mercury, plumbago, and antimony, if they have any effect at all, 
 it will not be upon the barnacles and sea-weed, but upon the iron 
 hull; and this any action they may exhibit will not tend to 
 improve the condition of. Some owners use merely a thick 
 coating of simple grease for ships going on distant voyages, and 
 so long as the friction of the water can carry off the weeds when 
 they have acquired a certain size, it may possibly do so as long as 
 the grease lasts; but what then? Touling of the iron hull of 
 course sets in. How far efiicacious this plan may be, in even its 
 best circumstances, I know not, but this I do know, that one 
 large house that has wisely eschewed anti-fouling compositions, 
 and uses this less hurtful means, pays probably the largest sums, 
 and certainly takes more care and pains in docking, scraping, and 
 painting its ships than any other in the port of London. And it 
 is well repaid for this expenditure. Paints of all kinds must be 
 peculiarly liable to be rubbed and scraped ofiF, and of course the 
 iron hull over such portions would then be completely unprotected, 
 and fouling and corrosion would go on as it pleased. 
 
 " I have been thus severe, but no more so than is deserved, upon 
 
192 APPENDIX. 
 
 paints and coating compositions of all kiuds^ because one of the 
 Antagonisms zinc sheathing has to encounter is the notion enter- 
 /tained by sailors and owners, and particularly the former, that 
 they should have 'something to paint the ship with.' A sailor 
 naturally likes to paint his ship, for much the same reason as a 
 child his toy-boat j and owners abide by paint for their iron ships 
 because they don't know what else on earth to do with them ; and 
 because to sheath them with copper is highly dangerous, as well as 
 expensive. 
 
 "Another antagonism to the trial of zinc sheathing amongst 
 merchant shipowners is the objection they have to having any- 
 thing done to the skin-plates for the purpose of securing the 
 sheathing. Mr. Daft effectually secured his insulated copper by 
 drilling holes partly into the thickness of the skin-plate, and 
 plugging them with wood or ebonite, and then driving the nails 
 which secured the sheathing into these plugs. For myself, I see 
 no objection whatever to this plan, but shipowners are excessively 
 timid about the slightest mechanical operations, although they 
 have no suspicion or fear of chemical action being painted all over 
 their ships. 
 
 " We have so far taken a broad survey of the nature, character, 
 and action of zinc sheathing, and are brought now to a considera- 
 tion of the best way of putting it on. 
 
 " It appears, then, that in order to perfectly protect iron hulls for 
 an indefinite period from corrosion — in fact, to preserve their thick- 
 ness in its full and original integrity, until every other part of the 
 vessel is thoroughly worn out — we have only to plate the bottoms 
 in a simpler, cheaper, and safer method than has ever before been 
 done. This Mr. Daft has accomplished by making all the joints 
 lap joints, and entirely avoiding butt joints and their costly and 
 evil consequences. To make the laps fair and flush, and perfectly 
 ■water-tight, they are, in addition to the ordinary punched caulking 
 (if that be thought desirable) , caulked with properly prepared strips 
 of compressed teak, and then the zinc sheathing is most firmly 
 secured by nailing on the sheets to the teak in the grooving in 
 the ordinary manner of fastening copper sheathing on wooden 
 vessels, the zinc being, at one and the same time, the complete 
 preserver of the iron hull and the essential metal for keeping , 
 the bottom perfectly clean for a number of years proportionate to 
 the thickness of the sheathing used. If, for example, a sheathing 
 of one twentieth of an inch thick be used — as a good stout sheath- 
 ing fit for a vessel of 3000 to 5000 tons would be — it would weigh 
 thirty ounces to the square foot, and assuming a loss of two ounces 
 per annum, and that when it was reduced to half its thickness re- 
 sheathing would be required, we have at least seven years of a 
 clean and safe bottom, without the least anxiety about it as to 
 
APPENDIX. 193 
 
 fouling or corrosion. It is important in its place to determine the 
 size and shape and appointments of our new iron fleet, but it seems 
 out of place to do anything before the very base and foundation of 
 the superstructure be settled. If our magnificent broadsides, 
 cupolas, monitors, or whatever we may come to, be dependent upon 
 any description of paints or compositions, and be really wanted on 
 service, they must all go to ruin by corrosion before the end of a 
 commission, or come into dock every six months to have their 
 hulls cleaned and re-painted, to say nothing of the diminished 
 value of a vessel which begins to foul from the day she leaves port, 
 and gradually but surely gets worse, until her boasted speed is re- 
 duced to two thirds, and even to half its original rate. 
 
 " Almost all iron ships as now built present longitudinal rows of 
 plates, alternately projecting and receding — ' in-and-out strakes,' 
 as they are called by shipbuilders. In these strakes the joints 
 are of two kinds — one made by the overlapping of the edge of 
 one plate upon another, and called the lap joint ; in the other, the 
 edges of the plates are planed smooth, and the ends brought close 
 to each other, the joint being made good by the riveting of the 
 ends of both plates to a common back-strap. That is termed a 
 butt joint, because the two ends merely ' abut' against each other. 
 The lap joint is in every way by far the stronger; the rivets pene- 
 trating both plates, and, being driven in red hot, by their shrink- 
 age exert such power that the lap joint, if properly made, is 
 absolutely stronger than the plates themselves. But such is not, 
 and never can be, the condition of the butt joint. That is a form 
 of joint that in its essential character is the very weakest possible. 
 It is really of the nature of a plate half cut through ; and a very 
 correct general notion of its condition may be given by comparing 
 it to a plank sawn across to the half of its thickness. Because a 
 saw-cut was formed of three pieces, a plank cut quite through and a 
 back piece, it would not cease to be a saw-cut ; and just so, although 
 the butt joint is formed of the two ends of two plates and a back- 
 strap, the line of particles in that back-strap facing the seam be- 
 tween the ends of the plates will be that portion of the metal 
 which will have to endure all the strain brought upon the joint. A 
 saw-cut weakens a plank more than the proportion of its depth to 
 the original thickness, because there is a leverage of the substance 
 of the wood, brought to bear during aliy strain, that opens the Cut 
 upon the front line of particles of the uncut remainder of the 
 plank, and "s^hich is thus liable to be rent asunder, and in this way 
 the, crack is easily continued. The back-strap of a butt joint is 
 always in the condition of the remainder of a saw-cut plank ; and, 
 as such butt joints are used for the vertical joints of the strakes, 
 there are many hundreds of such butt joints in a ship alwavs 
 liable to be strained open and split, and that too, it may be, all 
 
 13 
 
194 APPENDIX. 
 
 over the ship. When vessels strain across ocean waves, the butt 
 joints are exceedingly likely to give way ; and many iron vessels 
 have gone down from no other cause than the opening of 
 their butt joints. When iron vessels are strained, it is usually 
 along the lines of butt joints that they part asunder ; and, in 
 brief, all the accidents that arise from the defects of, or strain 
 upon, the fabric may be set down, with hardly an exception, to 
 the giving way of the butt joints. No one ever heard, that I know 
 of, of lap joints, where the workmanship was good, giving way ; 
 but the iron- shipbuilder prides himself -upon the finish of his butt 
 joints, and thus in the very pride of his craft confesses the in- 
 herent deficiency of the butt joint. Why should he pride himself 
 upon the extra care and finish bestowed upon it if it were as good 
 as the less-cared-for lap joint; and why should he use the lap" 
 joint for his horizontal strakes, and make an uneven irregular hull 
 for the ship, when with the butt joint he could make a fair and 
 flush hull if the butt joints were not inherently worse ? He cer- 
 tainly would reject the lap joint if it were not for its superior 
 strength. But the weakest part of a ship is its actual strength, 
 and therefore, as the lap joints are its strongest parts, the butt 
 joints detract from the entire stamina of the vessel. Now, in 
 putting the groove round each plate for his infilling of teak, Mr. 
 Daft uses a plan which entirely gets rid of the defective butt joint 
 altogether out of the ship. By putting the plates an inch apart, 
 he takes the joint out of the category of a saw-cut, and by putting 
 a narrow plate of the same thickness as the skin of the ship at the 
 back of the joint he virtually reduces the in-strake from three 
 feet wide to one. inch in width. It is still, however, of the nature 
 of a strake ; and the metal of the inner plate, when any strain 
 comes upon it, has sufficient extent of surface to bend into an 
 arch, and no single line of particles having to bear more than its 
 proper share of the strain, there is no longer any liability for the 
 metal to be pulled apart or to crack. The extravagant expense of 
 planing the ends of the iron skin-plates is entirely done away with, 
 the edges of the plates being left just as they come away from the 
 shears, and the teak, carefully dried, compressed, and forced 
 tightly in, securely caulks the joint, and makes the entire surface 
 of the hull perfectly fair and flush. The whole construction of the 
 ship under this process will be quicker and cheaper than ever; 
 there will be no inequalities in the. rigidity or strength of different 
 portions ; no sharp edges to encourage the commencement of oxi- 
 dation and fouling, and there will be the most suitable means of 
 nailing on a metal sheathing to protect the iron hull from corro- 
 sion from salt water when afloat. What Mr. Daft has done really 
 is to have turned the insecure butt joint into double lap joints ; the 
 result is mechanically right, and the wonder is that it was not seized 
 
APPENDIX. 195 
 
 upon by every builder the moment it was devised. But strong is 
 the force of babit : and it is a common failing of men to cberisb 
 most bigbly that which has given them the most trouble. Trouble- 
 some thingSj howeverj like troublesome people, are seldom good 
 for much. 
 
 " Both subjects, the construction of iron ships, and]zinc sheathing, 
 permit a great deal more to be said about them ; but a paper for a 
 society's evening meeting cannot go to the extent of a volume. I 
 will, therefore, only add that, as wooden ships are still (built in 
 large numbers for foreign voyages of long duration, solely because 
 of the fouling of iron ones, I do believe the adoption of Mr. 
 Daft's process of zinc sheathing, by enabling iron ships to under- 
 take voyages of any length of time in a perfectly clean state, will 
 throw into the iron-shipbuilding trade all the orders that would 
 otherwise go, as now and heretofore, to the builders in primaeval 
 wood. Iron ships are incomparably, stronger and are much lighter 
 than wooden ships, and can be made on finer lines. 
 
 " I now ask full discussion on these subjects, in which I have be- 
 come interested, in the firm conviction of their correctness and 
 importance, and which, for those reasons, I wish to see put to 
 practical trial by shipbuilders and shipowners." 
 
 Discussion. 
 
 " Mr. Haddan said he was afraid that Mr. Mackie had. sought 
 to prove too much, for this reason — that if all he had stated was 
 correct, iron vessels would wear four or five times as long as they 
 do now, and, consequently, the trade of shipbuilding would be re- 
 duced to the extent of four fifths, unless a very greatly increased 
 demand for ships arose. He had himself, tried to induce people to 
 make important changes in materials for manufacturing purposes. 
 Some years ago he brought forward a plan for building railway 
 carriages with, papier-mache, which would last twenty years ; but 
 on introducing the subject to a carriage builder, he would not en- 
 tertain it for a moment, because, he said, he did not want car- 
 riages to last twenty years, for, if they did, what would become of 
 his trade ? But, he added, if he could show him a plan by which 
 they would last only a year, he would take it up. He could hardly 
 suppose that the Admiralty authorities of the country were influ- 
 enced by these feelings, but he thought that they were in the habit 
 of waiting to see what other countries did ; and he believed if Mr. 
 Mackie or Mr. Daft could induce the Emperor of the French to 
 try this plan of zinc sheathing on one of his vessels, and it suc- 
 ceeded, our Government would adopt it instantly. He considered 
 this invention a very important one. He was not a shipbuilder, 
 
196 APPENDIX. 
 
 but understanding something of the properties of iron, and hearing 
 the explanation of the system which had been given this evening, 
 he believed it to be a sound one, and he hoped public pres- 
 sure would be brought to bear upon the Government to give it a^ 
 fair trial. 
 
 '' Mr. G. B. Galloway submitted that the question before the 
 meeting was one of paramount national importance. He would 
 refer to a statement which was made in this room at the meeting 
 of the Institute of Naval Architects in 1865, by Sir John D. Hay, 
 one of the present Lords of the Admiralty, who said that, unless 
 some mode were discovered to preserve the bottoms of iron ships, 
 in a short time we should have no iron navy in existence. He 
 (Mr. Galloway) begged to ask the author of the paper at what 
 dates the tests of this invention had been made under the auspices 
 of the Admiralty authorities ? 
 
 " Mr. Mackie replied in 1863 and 1864, at Shoeburyness, and 
 from 1865 up to the present time at Portsmouth. 
 
 ''Mr. Galloway said the quotation from the ' Times ' which had 
 been read lamented that no discovery had been made for the pre- 
 servation of the bottoms of iron ships, while they had the fact 
 before them that these tests were made prior to the date of that 
 article, when proofs had been afforded that this system was most 
 certainly a valuable one. It was a national disgrace that, in the 
 face of this invention, there should still be going on the enormous 
 waste of public money resulting from the fouling of the bottoms of 
 our iron navy. 
 
 " Mr. C. P. T. Young said he had listened with great satisfaction 
 to Mr. Mackie's paper. He had had many opportunities of observ- 
 ing the evils which resulted from the fouling of ships^ bottoms, the 
 effects of which had been in no way exaggerated by Mr. Mackie. 
 The idea was still held that the copper bottom of a vessel kept clean 
 because it was of itself a poisonous material. However poisonous 
 it might be in itself, it had not a destructive effect upon the organ- 
 isms which infested the bottoms of ships. The rapidity with which 
 this fouling proceeded was hardly to be credited. The Southampton 
 pilot boats, during the summer months, had to lie ashore every 
 fortnight to clean off the fouling, and the St. Mawes pilots had to do 
 the same. It was stated that the 'Gloire' and other French 
 iron-clads had, on an average, passed fifty-five days each in dock 
 during a period of little over fourteen months only to remove the 
 fouling. With regard to the cost of keeping ships' bottoms clean, 
 it was stated that the P. and O. Company spent £70,000 annually 
 simply for keeping their ships' bottoms clean. One iron ship of 
 800 tons, which had been eight months in a warm latitude, had 
 thirty cart loads of barnacles taken off her bottom, an estimated 
 weight of twenty-eight tons. It was calculated that our iron-clads 
 
APPENDIX. 197 
 
 had eacli to spend fourteen days every six months in dock to remove 
 the fouling, although they were frequently hogged. The iron 
 steamer 'Megsera^ was found to iilcur an increased cost in running 
 of £23 per day through having a foul bottom, the same amount of 
 fuel only producing seven knots an hour in place of ten. It 
 had been proved, from careful tests made with the Dublin and 
 Holyhead mail steam-packets, which were very fast boats, that, 
 after they had been out of dock two months, their speed uniformly 
 fell off from half a mile to one mile per hour from fouling only. 
 With regard to the alleged poisonous effects of copper, any one who 
 had seen the oysters on the coast of Cornwall knew that they were 
 perfectly green coloured from being impregnated with copper, so 
 that it was impossible to eat them, and yet they lived and thrived. 
 Eighty tons of barnacles were taken off the copper bottom of an 
 old wooden ship which was broken up some years since. About a 
 year and a half ago an experiment was tried, at the instance of the 
 Scottish Shipbuilders' Association, as to the powers and advantages 
 of the so-called poisoning process. The four quarters' of an iron 
 plate were each thickly coated with the most poisonous compounds 
 that could be. found — arsenic, corrosive sublimate, &c. — and the 
 plate was immersed in sea- water for some months. When taken 
 up it was found to be in the most foul condition possible, and it 
 so happened that the largest barnacle of all had placed itself at the 
 junction of all the four compounds. It woiild hardly be believed 
 that there were persons who, even at the present day, would deny 
 the existence of galvanic action ; but it would seem that this idea 
 was held more generally than would at first be supposed, when we 
 found the use of yellow metal and copper on iron ships still adhered 
 to in the navy. Mr. Young called the attention of the meeting 
 to a piece of iron plate on the table, which had been experimented 
 on, by covering it with Muntz's yellow metal, insulated from the 
 iron by vulcanised india-rubber and felt ; and although the edges 
 were protected so that no water could get between the copper and 
 the iron, yet, after having been immersed for several months, the 
 iron was found to be very much eaten away, owing to the galvanic 
 action. The 'Achilles,' when docked at Plymouth, was found to 
 have her plates eaten in from -rFtli to t-q'^^ of an inch deep, and 
 was very foul. Numerous other instances were given. The 'Royal 
 Oak ' iron-clad, with a coppered bottom on a wood sheathing, was 
 found to have had her plates eaten by corrosion to the depth of 
 three eighths of an inch in less than eight months. With regard 
 to the employment of poisonous paints, if the barnacles held on by 
 their mouths there might be some sense in using them, but they 
 hold on by their feet instead. Some of the barnacles taken off a 
 plate painted with arsenic were boiled and given to a cat, and the 
 animal died with all the symptoms of arsenical poisoning, while 
 
198 APPENDIX. 
 
 the barnacles themselves remained wholly unaffected by the com- 
 pound. 
 
 " Mr. BoTLY said they were much indebted to Mr. Mackie for 
 the paper he had read ; it was a matter of the greatest importance, 
 not only to the Society, but to the country at large, that such a 
 subject should have been brought forward. The paper treated of 
 two great improvements in the construction of iron ships, viz. the 
 lap joint for the plates, and the zinc sheathing as a protection 
 against fouling. Both these matters were of the utmost import- 
 ance, and deserved careful consideration. 
 
 " Mr. Campin asked whether the action of the zinc sheathing, 
 in keeping off the barnacles, was supposed to be due to the elec- 
 tric current, or merely to the wearing away of the surface of the 
 zinc. 
 
 " The Chairman said the paper sufficiently explained that it was 
 the slipping away of the surface of the zinc from the feet of the 
 barnacles, by exfoUation of the metal, which kept the bottom 
 clean. 
 
 "Mr. Blackie inquired whether the zinc to be used for sheath- 
 ing was prepared in any special manner different from the ordinary , 
 mode of manufacture. 
 
 " Mr. Mackie replied that'the zinc was prepared in the usual 
 way. It might, however, be found desirable to adopt some anneal- 
 ing process, to get rid of any extreme rigidity of the metal. 
 
 " Mr. Blackie remarked that those who had zinc water-cisterns 
 would probably have observed that an incrustation took place on 
 the zinc. He would like to know whether the action of fresh 
 water on zinc was different to that of sea-water. 
 
 " Mr. Mackie replied that fresh water would produce a deposit 
 on the zinc by evaporation ; but when iron was present, salt water 
 set up a galvanic action between the two metals. 
 
 " Mr. Blackie then called attention to the question of the ex- 
 pansion and contraction of zinc as compared with iron, and ex- 
 pressed his opinion that there was great liability of the zinc crack- 
 ing. He would also like to be informed as to what would be the 
 cost of plating a ship with zinc as compared with copper, the cost 
 of cleaning being added. The cost of sheathing a vessel's bottom 
 with zinc, he apprehended, would be considerable, and it appeared 
 it would require to be renewed, owing to the wasting of the metal, 
 in the course of a few years. The question, therefore, arose, 
 whether the cost would not be greater than that of docking the 
 ship occasionally, and clearing off the fouling. 
 
 " Mr. E. J. Reed (Chief Constructor of the Navy) said the paper 
 appeared to be a very able and interesting one, but one or two 
 things had been said in it which he could not allow to pass with- 
 out notice. He thought the theory enunciated as to the weakness 
 
APPENDIX. 199 
 
 of the butt joint, viz. that there was liability of the joint breaking 
 at the line where the plates touched, was erroneous ; in practice it 
 was found that fracture, when it did occur, took place in the line 
 of rivets. He did not say the butt joints never broke at the line of 
 junction ; but, when they did so, it arose from the fibre of the iron 
 in the butt strap being put across, instead of lengthwise. His 
 opinion was that, with ordinary good iron shipbuilding work, when 
 pains were taken to put the fibre of the iron in the direction of the 
 ' fibre of the plate, and with a slight increase of thickness of the butt- 
 strap, it was not found that the butt broke in the way suggested in 
 the paper. With regard to the subject of fouling, he might say that 
 to his certain knowledge it had been a matter of most anxious con- 
 sideration, and also of experiment, by the Admiralty ever since tbe 
 introduction of iron ships into the navy. For two or three years 
 the late Board of Admiralty and the Controller of the Navy 
 sanctioned a large number of experiments with anti-fouHng and 
 other compounds, but with, he was bound to say, no very satisfac- 
 tory results ; indeed, there seemed little promise of anti-fouling 
 compounds doing all that was desirable in keeping iron ships' 
 bottoms clean. He thought much was yet to be done in that 
 direction, particularly by getting rid of the irregularities of the 
 surface of the immersed bottom, and making it perfectly flush and 
 even, so that it could be easily cleaned by being brushed while 
 afloat, as was done in former times with wooden ships. But still 
 he thought any advantage thus obtained would be very inferior to 
 an arrangement which would secure a permanently clean bottom. 
 The system described in the paper was certainly entitled to great 
 consideration, in spite of any little difficulties that might at first 
 appear to belong to it. For instance, at first there appeared to be 
 considerable difficulty in caulking the joints, but his own feeling 
 was that in a matter of this magnitude and importance mere 
 mechanical difficulties of this kind would soon be got over. We 
 had already encountered, and were still encountering, very much 
 larger difficulties, and we could not now afi'ord to be deterred by 
 trifles from adopting any real improvements. He might, however, 
 say that no experiments had yet been made with this invention 
 which would carry complete conviction to the Government. The 
 minds of all those persons who were responsible must first be fully 
 satisfied. For his own part he did not attach much value to the 
 experiments at Shoeburyness ; moreover, they were on too small a 
 scale to warrant the formation of any conclusion upon them. In 
 many instances, no doubt, when the copper sheathing had been 
 placed in contact with the iron, a most destructive galvanic action 
 had taken place, but in the case of the ' Koyal Oak ' and some 
 other vessels, a layer of wood was interposed between the iron and 
 the copper, and he could state the galvanic action had now been 
 
200 APPENDIX. 
 
 perfectly prevented. The inspection of ships on the Mediterranean 
 station showed that the iron plates, insulated from copper by only 
 a single layer of wood, remained perfect. He entreated those who 
 had the success of this invention at heart to make experiments on 
 a large scale, such as would satisfy the Government. He believed 
 the Portsmouth experiments were valuable, though he knew they 
 were not conclusive to some persons who saw them. The inertia 
 which was charged against the Admiralty in this matter was equally 
 applicable to private shipowners, for he was not aware of this 
 system having been adopted by them any more than by the 
 Government. 
 
 " Mr. Young remarked that it had been found that the wood 
 sheathing on the iron plates was an insufficient insulation. This 
 had been shown in the French and Spanish vessels. The plan 
 might answer if the ships were not exposed to heavy seas j but by 
 these and other violent shocks contact between the iron and copper 
 was often produced, and galvanic action was set up. 
 
 " Mr. Mackie, in reply upon the discussion, said he was glad to 
 have had the pleasure of listening to the remarks of Mr. Reed. 
 That gentleman, he was sure, knew enough of him personally to be 
 quite aware that if he used strong language in reference to the pro- 
 ceedings of Government, it was not out of personal animosity, or a 
 desire to attack the Government or their officials, but simply because 
 one who attempted to act upon the inertia always existing in Govern- 
 ment departments, must express himself strongly, or he would have 
 no hope of being listened to. With regard to the question of the 
 cost of sheathing with zinc, it was stated in the paper that it would 
 probably be one third that of copper. The copper required to be 
 replaced on wooden ships every three or four years, while zinc 
 would last, at a minimum, from five to seven years, and might be 
 made to last from twelve to fourteen years, according to the thick- 
 ness of it. With regard to the question of the expansion of zinc, 
 he believed the difference in the amount of expansion and contrac- 
 tion between the zinc and iron would be very small in temperatures 
 only ranging from 60° to 70°, or 80°, and would not be greater than 
 would be relieved by a slight buckling of the zinc plate. He had 
 not been able to go fully into all Mr. Daft's ideas with regard to 
 the jointing of iron plates, but he had no disposition to measure 
 his own experience in that matter with that of a gentleman like 
 Mr. Reed. He did not gather, however, that Mr. Reed considered 
 Mr. Daft's joint to be weaker than the butt joint. On the ques- 
 tion of putting the copper sheathing on iron vessels over wood 
 planking as an insulating material, he accepted Mr. Reed's state- 
 ment of the result as perfectly correct. Still, it must be borne in 
 mind that water would percolate wherever there was a crack, and 
 so long as connection was made by the water between two opposing 
 
APPENDIX. 201 
 
 elementSj so long he thought there was danger of corrosion by 
 galvanic action. 
 
 " Mr. Reed said he should be sorry it should be supposed that 
 he had implied that the plan of placing the copper sheathing on 
 ■wood, as an insulating material, was quite satisfactory. If the 
 plan described in the paper were successful, it would be immeasur- 
 ably superior. 
 
 " Mr. Mackie was glad to hear that remark from Mr. Reed. 
 He agreed with that gentleman that it was essential this system 
 should be tried on a larger scale than it had been ; and that this 
 might be done was one great reason for his bringing the subject 
 before this meeting. With regard to the putting a wooden layer 
 to receive the copper sheathing, there was this further objection to 
 it, that, whatever quantity of wood was put on the outside of the 
 hull, it practically increased the size of the vessel, and, to that 
 extent, increased the amount of resistance ; and for every square 
 foot of such increase there was a loss of one nominal horse-power, 
 With regard to the carrying out of experiments on a large scale, 
 he would ask was the inventor of this plan bound to build a vessel 
 at his own expense, send it to sea, and keep it there a suf&cient 
 time to afford a thoroughly satisfactory test of the merits of the 
 system ? Mr. Reed might possibly be right in saying that the 
 experiments at Shoeburyness were worth nothing ; but the experi- 
 ments at Portsmouth were carried out under official authority, and 
 he was going to say nearly officially spoilt. If this system had 
 merit, let it be tried on a proper scale ; if it had no merit, he (Mr. 
 Mackie) would be amongst the first to give it up. By this system 
 the sheathing could be applied to the hull of the ship direct. If 
 it required any insulating material, however thin, it did not realise 
 what was claimed for it. He might add that, if the Government 
 took experiments in hand at all, the least they could do was to 
 carry them through ; because, if they did not, they put the in- 
 ventor in an unfair position. He believed the system would have 
 been tried in the mercantile navy ere this if the trial experiments 
 had not been in Government hands ; but that being the case, people 
 naturally waited the result of the Government trials. He, there- 
 fore, said, let the inventor try an experiment according to his own 
 plans. Let him have some small iron vessel, even a condemned 
 one, and let it be sheathed on his system. If, then, it was found 
 wanting, let it be given up. 
 
 ''The Chairman said, as to the importance of the subject treated 
 in the paper, there could be no doubt. It was a national question 
 to overcome the difficulties which still attached to the use of iron 
 vessels. Iron had been so completely proved to be the better 
 material in naval construction that the Government had largely 
 adopted it ; and yet there was one defect attaching to it, viz. that 
 
202 APPENDIX. 
 
 iron ships would foul very quickly. The means hitherto adopted 
 were clearly insufficient as a remedy for the evil. The poisonous 
 compounds spoken of he thought might be fairly dismissed from 
 their minds as being playthings in connection with a very serious 
 subject. Copper sheathing appeared very inapplicablcj for when in 
 contact with iron it invariably had the effect of corroding it, 
 because the salt water would percolate between the two metals ; 
 and, moreover, the copper sheathing itself would fail in its purpose 
 frorn the want of exfoliation of the surface. With regard to the 
 insulation of the two metals by the interposition of a wooden layer, 
 he agreed with Mr. Reed that the iron would be effectually pro- 
 tected so long as no metallic contact took place. The moisture- 
 between the two metals would not be sufficient to set up galvanic 
 action, the battery would be in the condition of an ' open ' battery, 
 not a ' closed ' one. There was, however, great difficulty in 
 maintaining perfect separation, because wire, even of tV*^ inch 
 gauge, was sufficient to transmit a considerable current and produce 
 a great amount of mischief upon the iron, and it was hardly to be 
 supposed that the two enormous surfaces could be long kept 
 perfectly separated without metallic connection being formed 
 between them. What surprised him, somewhat, on hearing this 
 paper was the very slow rate of exfoliation of the zinc. He had 
 himself made experiments upon the action of the salt water upon 
 zinc in contact with iron, and he found the zinc acquired weight 
 up to about three months, but after that period a sensible diminu- 
 tion in weight took place. The author of the paper stated that the 
 amount of the oxidation of the zinc was not more than 1-|- oz. or 
 2 oz., even if the exfoliation was made more active by an increased 
 galvanic action. It would be interesting to ascertain whether 
 there was any increased exfoliation when the ship was in motion. 
 No doubt there would be some increase, but experiment would 
 determine the amount. No doiibt, chemically, zinc sheathing would 
 protect the bottom of the vessel entirely, for even if a sheet of the 
 metal were displaced there would still be the influence of the zinc 
 in contact with the iron. So far, then, the invention appeared 
 to him to be an exceedingly promising one, and one which he 
 thought should certainly be tried seriously by the Admiralty. With 
 regard to the observations of Mr. Reed, he thought he had stated 
 the case very fairly, and he believed personally he would be disposed 
 to afford the invention every trial it required ; but, if the experi- 
 ment at Portsmouth was to be taken as evidence of the anxiety of 
 the Admiralty to inquire into the merits of new inventions, he 
 thought in this case an injury had been done to the inventor. 
 There was nothing, he thought, more destructive to the interests of 
 an inventor than an imperfect trial. 
 
 " Mr. Reed thought it due to the Admiralty to say that the 
 
APPENDIX. 203 
 
 experiment was not initiated by them. They merely gave per- 
 mission to Mr. Daft to put down some plates prepared on his 
 system^ but they were in no way pledged to go on with the 
 experiments. At the same time, having gone to the extent they 
 did, it might have been desirable that they should have continued 
 the experiments further. He merely wished to say that the 
 Admiralty did not initiate the experiments and then suddenly drop 
 them. (Vide p. 134 ; also p. 186 in Appendix.) 
 
 " The Chairman said that altered the case in some respects ; 
 but he maintained that- even the sanctioning of experiments 
 implied, he thought, a continuation of them; those who were 
 practically acquainted with the difficulties appertaining to the 
 introduction of inventions would appreciate more than official 
 personages could possibly do the great hindrance caused by incom- 
 plete experiments to the progress of an invention. If the inter- 
 vention of the Government were entirely refused, the inventor was 
 free to act as he pleased; but from the moment he placed his 
 invention in the hands of the Government he was practically shut 
 out from the public until a verdict upon it had been pronounced. 
 He thought the Government might spend a few thousands a year 
 very well in making really serious experiments upon questions of 
 this nature. Even if such an invention as this were tried upon a 
 merchant ship it would be no convincing proof to the Government 
 of its merit. The Government must naake its own experiments to 
 determine its value. With regard to the mechanical mode of 
 joining the plates, he thought it sufficient for this invention if it 
 was admitted that there was no inconvenience thus caused. He 
 did not think any great weight was to be attached to the question 
 of the buckling of the plates ; if the back-strap was carefully put 
 on, there would be no fear of fracture unless, as mentioned by Mr. 
 Reed, the back-strap had the fibre in the wrong direction. He 
 thought Mr. Mackie had brought the whole subject very ably and 
 fairly before them, and he was sure they could do no less than give 
 him their thanks for having done so. 
 
 The vote of thanks was then passed. 
 
 The author learns that since this paper was read by Mr. Mackie 
 he has carried out laboratory experiments to meet the ele.ctrical 
 objections raised by Mr. Siemens, and finds that, after completely 
 immersing in salt water three batteries, respectively consisting of 
 a plate of iron insulated by wood from a plate of zinc, of iron in- 
 sulated from iron, and iron insulated from copper, he has obtained 
 three distinct grades of chemical action — the fluid in the bath of the 
 zinc and iron elements being the least affected, the action of the 
 salt water joer se being considerable on the iron plates, whilst ochre 
 was freely deposited in the bath of the copper and iron elements. 
 
304 APPENDIX. 
 
 Mr. Mackie's experiments are not yet published, as lie considers 
 they should be repeated with the greatest possible care, to avoid 
 the possibility of erroneous theoretical explanations of the action 
 which takes place, and which the author believes he regards as 
 probably of an electrolytic nature. His object has been to show 
 that totally submerged elements are not in the condition of par- 
 tially submerged elements, in which he regards the cushion of air 
 at the open ends as an insulator of the plates, across which a 
 metallic wire is a necessary conducting bridge for the electricity. 
 
 FOULING. 
 
 The 'Times' of May 6th, 1867, states, in the "Naval and Mili- 
 tary Intelligence," that "Her Majesty's iron steam store ship 
 ' Supply ' has been absent from Woolwich over six months, con- 
 siderably beyond her usual time, which is accounted for by the/o?«? 
 state of her bottom. In order to remedy the defect she was ' hove 
 over,' and scraped by the mechanical means at hand at Ascension." 
 
 In reference to the clean state in which the bottom of the " Great 
 Eastern " was reported to have been by the ' Times ' (as shown at 
 page 79 of this work), when examined on the gridiron at Liverpool, 
 in the beginning of the present year, Mr. Robert Murray, of 
 Southampton, states, in a letter to 'Engineering' of May 17th, 
 1867, that " tla.e whole bottom was thickly encrusted over with 
 shellfish to a depth varying from five inches to nine inches, the 
 weight of which was estimated at from 250 to 300 tons " ! ! So 
 much for the efiB.ciency of " anti-fouling " compositions. 
 
 It will be remembered that on the late occasion of the failure of 
 the engines of the iron-clad ship "Minotaur," the ' Standard' was 
 the first to announce the circumstance ; but the ' Times ' gave the 
 statement a flat contradiction, affirming that the engines " on both 
 days worked admirably," but at a later date admitted that there 
 . had been a breakdown, thus stultifying its former statement ! 
 
 IMPROVED CONSTRUCTION. 
 
 The ' Standard,' of May 23rd, 1867, in an article on " Naval 
 Designs," which describes the features of a movement initiated by 
 the First Lord of the Admiralty, requesting the most eminent 
 shipbuilders to submit designs for iron-clad men-of-war to the 
 Admiralty, states that " zincing the bottom of the ship will be 
 entertained." 
 
 It is gratifying to learn from this that steps will now be taken 
 to preserve the iron hulls of our ships from corrosion and fouling, 
 
APPENDIX. 205 
 
 by the employment of zinc as a sheathing, in place of copper or 
 yellow metal, or the use of paints or compositions. 
 
 Of its success there can be no doubt, and it is hoped that the 
 plan of construction invented and patented by Mr. Daft, for ob- 
 taining the advantages gained by abolishing " butts " and using the 
 zinc sheathing, will be carried out in its integrity, so as to enable 
 a full and fair trial to be made. 
 
 The article concludes with the remark that "we cannot but 
 believe that the country will welcome every sincere effort made to 
 secure the best plans for our national defences, ashore or afloat, 
 and will rejoice to see a determination displayed not to permit 
 prejudices, ofScial or civilian, to interfere with the attainment of 
 the most effective results." 
 
 The remark was made by Dr. Robison, that " an eixperiment does 
 not establish a general proposition, and never can do more than 
 prove a particular fact," but in the case of the experimental plates 
 which have been described in this work it has been denied by 
 some that even the particular fact they were arranged to illustrate 
 has been proved ! 
 
 In reply to Dr. Robison's remarks, there can be no doubt that, 
 as the late Mr. Charles Wye Williams has observed, " The proving 
 a fact is a decided step in actual progress, and enables us to draw 
 inferences and illustrations, which, leading to other facts, bring us 
 to absolute demonstration." 
 
 It is to be regretted that in some instances even the proof of a 
 fact is not always admitted, and that this very circumstance of its 
 being proved should act as a difficulty. As to trying to prove a 
 a fact, there are, it may be remarked, two ways of going to work — 
 one so that it shall succeed, the other so that it shaU not ; and it 
 sometimes unfortunately happens that preference is given to the 
 latter mode instead of the former. 
 
 There can be no reason why experiments should not be tried ; in 
 fact, they may be generally considered necessary, but it is most 
 iniportant that all should be fairly carried out, and honestly taken 
 in hand, if it be really desired to arrive at correct results, or obtain 
 any benefit from them. 
 
 It may be here remarked, that persons will be found to object 
 to the cost of constructing and sheathing an iron ship on this 
 plan because it would be more expensive at the outset than 
 smearing, plastering, painting, or glueing ; but such persons do not 
 object to the continued evil of docking, loss of time in this opera- 
 tion, and the liability to fouling and corrosion perpetuated by the 
 old system, and fail to appreciate the advantages of uniform speed 
 and cleanliness, and safety from corrosion, which accrue for some 
 three or four years or more if desired, by the use of this new 
 
206 APPENDIX. 
 
 system of " Dafting," and forget, as has been shown at page 136, 
 that the entire cost may be almost saved in the first year. 
 
 Again, it is confidently objected by those who do not understand 
 the matter that, if zinc sheathing is to be used, the existing ships 
 of iron cannot be benefited thereby, as they allege a ' ship must be 
 specially constructed for its application. A reference to page 131 
 will be a suflBicient reply to this incorrect assertion ; and although it 
 is admitted, and is evident, that it does not make so good and 
 workmanlike a job as if the ship were " Dafted" or specially built 
 for the purpose, still a moment's reflection will show to any think- 
 ing practical man that the advantages and benefits ensured by its 
 employment, as well as the fact that none of them are gained by 
 any mode yet proposed or tried, would render this point of little 
 moment ; and even if it did require a little more care of the ship to 
 keep her off the ground, or clear of docks, wharves, barges, lighters, 
 &c., to prevent stripping the sheathing, still this little trouble would 
 be amply repaid by the advantages secured by its adoption. 
 
 It is not often that objections are raised to building a single or 
 double wooden ship over an iron hull, to carry the copper or yellow 
 metal, nor are the great trouble, expense, and waste of time 
 incurred thereby considered of any moment ; yet zinc, which does 
 not require any trouble, expense, or precautions of a similar kind, 
 is evidently not thought of sufficient importance to receive any 
 attention. Possibly its freedom from requiring such precautions 
 may be considered an objection. 
 
 The " Dafting " system embodies three particular features : — 
 First, a novel and superior mode of constructing iron ships ; the 
 second, obtaining flush and stronger hulls, on which, if any one is 
 foolish enough to prefer it, they may nail copper or yellow-metal 
 sheathing; and the third, the employment of sheets of metallic 
 zinc as a protective from fouling and a preservative from corrosion 
 for the hulls of iron ships. Consequently to give the system a fair 
 trial, all thtise three points should be treated as a whole. 
 
INDEX. 
 
 AAR 
 
 « A ARON MANBY" iron steamboat, her 
 il- voyage from London to Paris, 26 . 
 
 Abel (Mr.), on advantages of zinc sheath- 
 ing, 135 
 
 Absorption of water by wooden ships, 3 
 
 "Achilles" iron-clad, cost and effects of 
 application of anti-fonling composition 
 to, 58 5 effects of fouling on, 70 ; effects 
 of corrosion on, 82 
 
 wooden ship of war, comparative cost 
 
 of building and maintenance of, 4 
 
 Adams (Mr. W. B.) on the earlier attempts 
 at iron ships, 1 5 
 
 Admiralty, inspection by, of Mr. Daft's in- 
 vention for sheathing iron vessels, at 
 Portsmouth, 148 
 
 Advantages of iron in the construction of 
 ships, 12 
 
 to be gained by adoption of Mr. 
 
 Daft's plan of construction and sheath- 
 ing iron ships, 136 
 
 " Agincourt," state of, from fouling, 56 
 
 "Ajax" wooden ship, comparative cost of 
 building and maintenance of, 4 
 
 Allen (Mr.), observations upon Mr. Daft's 
 plan of constructing iron ships, 121 
 
 " Amazon " armour-plated wooden ship, 
 sinking of, 10 
 
 Anti-fouling compositions : Hay's, 57, 67, 
 70; Wilson's, 57; Crispin's, 57; Green's, 
 58 ; Lee's, 67 ; Moresby's, 67 ; Clark's, 
 67 ; Ince and North's, 67 ; Chanter's or 
 Weddersted's, 67; Grantham's, 67; 
 Parker's, 67; the 'Times' on, 70; Gis- 
 bome's, 86 ; Mallet's, 86 ; ' Times ' on, 
 98 ; Mclnnes, 99 
 
 Appold (Mr. J. -G.), on disadvantages of 
 galvanising, 129 
 
 Archimedes, fastening and sheathing of 
 ship of, 36 
 
 "Ardent" wooden ship, comparative cost 
 of building and maintenance of, 4 
 
 Armour-plated wooden ships, 8 , 
 
 Average time spent in dock for purposes of 
 cleaning by iron-clad ships, 60 
 
 CLA 
 
 BAKEWELL (Mr.), list of metals that 
 excite electrity by mutual action, 88 
 ' Baltimore American '' on cleaning bottoms 
 
 of monitors, 77 
 Barnaby (Mr. N.), on improved mode of 
 
 applying iron, 110 
 Barnacles, photograph of, taken from 
 
 H.M.S. " Phoenix," 69 
 Belcher (Admiral Sir'E.), on fouling, 68; 
 
 on use of zinc, 135 
 Bentham (Sir S.), proposes iron for ships, 
 
 25 
 " Black Prince," cost of construction of, 
 
 23 
 — results of application of anti-corrosive 
 
 compositions to, 99 
 Bourne (Mr. John) on " marine gliie " for 
 
 the bottoms of iron ships, 68 ; action of 
 
 zinc, 134 
 Brande (Professor), on action of zinc, 134 
 
 and 135 
 Bulkheads, transverse water-tight, in 
 
 wooden ships, introduction of, 31 
 " Butt " versus " lap " joints In iron ships, 
 
 103, 105 
 
 " riALEDONIA," plan of sheathing of, 
 \J 47 
 
 Causes of corrosion of iron ships, 81 
 Chanter's or Weddersted's anti-fouling 
 
 composition, effects of, 67 
 Charles II, method of sheathing vessels in 
 
 time of, 37 
 Chatfield (Mr.) on the average durability 
 
 of our sailing wooden men-of-war, 5 
 Chatham Harbour, state of floating fire- 
 engine in, 67 
 Chemical action of metals in contact with 
 
 sea-water, want of attention to, 40 ; 
 
 analysis of the subject, 41 
 Chronology of iron ships, 25 
 City of Dublin Steam Packet Company, 
 
 effects of fouling on steamers of, 75 
 Clark's anti-fouling composition, effects of, 
 
 67: 
 
208 
 
 INDEX. 
 
 CLA 
 
 Clarke (Mr. Edwin), his experiments on 
 iron, 104 
 
 Coles (Captain C. P.) on the prevention of 
 fouling of iron ships, 11 ; on iron as a 
 material for shipbuilding, 23 
 
 Comparative cost of repairing and length 
 of service of vpooden ships, 3 
 
 " Composite " ships, 5 ; effects of corro- 
 sion in, 7 and 93 
 
 Controller of the Navy on the relative ad- 
 vantages and disadvantages of iron and 
 wood in the construction of ships, 16 ; 
 curious ohjection made by, to use of iron 
 ships in the Navy, 18 
 
 Copper, preparation of, its effects on the 
 "Atrato," 43; on the "VaUant," 43; 
 on the " Orontes," 43 ; on the " Royal 
 Oak," 43 ; action of, on hull of iron 
 ships, 84, 86 ; the ' Standard' on, 91 
 
 Corrosion of iron ships, Mr. Leo Daft on, 
 78 ; causes of, 81 ; effects of, 82 ; rapi- 
 dity of, in water of tropics, 82 ; ex- 
 ' amples of the rapidity and extent of, 
 83; 'Mechanics' Magazine' on, 84; 
 various patents for prevention of, 85 ; 
 'Standard' on, 91; 'Steam Shipping 
 Journal' on, 94; zinc the only metiS 
 applicable for sheathing in order to pre- 
 vent, 100 
 
 Corry (Mr.), on importance of iron for 
 shipbuilding, 2. 
 
 Cost of repairing and maintenance of 
 wooden ships of war, 3, 4 
 
 of construction of iron ships, 22 
 
 of "Warrior," 23; "Black 
 
 Prince," 23; "Defence," 23; "Resist- 
 ance," 23 
 
 DAFT (Mr. T. B.),his system of constract- 
 lug and sheathing iron vessels, 39, 102 ; 
 paper by, on joining of plates in iron 
 shipbuilding, 114; experiments on zinc 
 sheathing^by, 124, 148 ; modification of 
 system of slieathing of, 131 ; estimate 
 of saving by adoption of plan of con- 
 struction and sheathing of, 136 ; ad- 
 vantages to be derived from same, 136 ; 
 'Standard' on his sheathing for iron 
 ships, 154 
 
 Daft (Mr. Leo) on the prevention of 
 fouling and corrosion of iron ships, 78 
 
 Davy (Sir Humphtey),hi8 iron "protectors" 
 in connection with copper sheathing, 40, 
 42,89 
 
 Defects of iron in the constcuction of 
 ships, 12 
 
 " Defence," cost of construction of, 23 
 
 FIS 
 
 Desiderata in iron ships, ' Engineer' on, 79 
 Dickinson's (Robert) patent improvements 
 
 in construction of iron ships, 85 
 Difficulty of obtaining suitable timber for 
 
 building wooden ships, 2 
 Disadvantages of wood in the construction 
 
 of ships, 1 
 Discovery of boat sheathed with lead in 
 
 Mediterranean, supposed to have been 
 
 submerged 1400 years, 36 
 a Roman ship sheathed with lead in 
 
 Lake of Nemi, 36 
 Douglas (Sir Howard), his opinion of iron 
 
 ships, 20 
 Dupuy de L6me (M.) uses copper on iro u 
 
 hulls, 44 
 
 IjlFFECTS of working of machinery in 
 -J wooden ships, 7 
 " Elburka," the first iron vessel that made 
 
 an ocean voyage, 27 ' 
 
 .Emperor of the French, introduction of 
 
 iron-cased floating batteries by, during 
 
 Crimean war, 33 
 ' Engineer ' on desiderata in iron ships, 79 
 ' Engineering' on absorption of water by 
 
 wooden ships, 3 
 Engledue (Captain J. E.), on failure of 
 
 compositions, 90 
 Estimate of saving effected by adoption of 
 
 Mr. Daft's plan of construction and 
 
 sheathing of iron ships, 136 
 Examples of the rapidity and extent of 
 
 corrosion of iron ships, 83 
 Experiments for obtaining insulation, 95 ; 
 
 to ascertain the strength of iron vessels, 
 
 with Mr. Daft's plan of sheathing iron 
 
 ships, 186 
 
 FALLACY of idea of poisoning process 
 of copper on zoophytes on ships' bot- 
 toms, 43 
 Fairbairn (Dr.) on the advantages of iron 
 ships over wooden ones, 14, 19 ; on the 
 drawbacks of iron in shipbuilding, 21 ; ~ 
 his experiments on various iron plates, 
 104 ; on action of zinc sheathing, 135 
 Faraday (Professor) on the association of 
 
 iron with other metallic substances, 89 
 First record of iron boat or floating vessel, 
 
 25 
 First iron vessel built on the Mersey, 27 
 
 that made an ocean voyage, 27 
 
 ever used in America, 27 
 
 Fishbourne (Captain E. G.), on fouling of 
 iron ships, 55 
 
INDEX. 
 
 209 
 
 FLO 
 
 Floating (iron-cased) wooden, batteries, 
 introduction of, 33 
 
 Floating fire-engine in Chatliam Harbour, 
 state of bottom of, 67 
 
 Fonling of ships' bottoms, 50 ; number of 
 patents taken out to prevent, 50 ; con- 
 sequences of, 50 ; Mr. Lamport on, 51, 
 52; Mr. Grantham on, 51, 52; enor- 
 mous loss of money and time involved 
 by, 52 ; average number of days passed 
 in dock by six of the iron-plated French 
 Navy in consequence of, 52 ; Mr. Mallet 
 on, 53 ; Captain Seiwyn on, 53 ; Lord 
 Clarence Paget on, 53 ; Admiral Sir E. 
 Belcher on, 54 ; the ' Times ' on, 54, 55, 
 56, 67, 82 ; Captain Fishbourne on, 55 ; 
 Peninsular and Oriental Company's su- 
 perintendent on, 57 ; Admiral Halsted 
 on, 62 ; Mr. Leo Daft on, 78 ; Sir John 
 Pakington on, 76; mechanical means 
 for clearing off, whilst ship is afloat, 
 76 ; mode of clearing off from American 
 monitors, 77 ; Mr. C. F. T. Young on, 
 196 ; " Supply," 204 
 
 French Government, indifference of, to 
 effects of injury to iron-clads by use of 
 copper sheathing, 44 
 
 GALVANIC action induced by use of 
 copper on iron ships' bottoms, 84 
 
 Galvanising the hulls of iron ships, pro- 
 posal for, 128 
 
 Gisborne's anti-corrosive paint, 86 
 
 Gmelin, zinc protects iron, 133 
 
 Graham (Professor) on action of zinc, 133 
 
 Grantham's anti-foulingcomposition, effects 
 of, 67 
 
 Grantham (Mr.) on the effects of VforVing 
 of machinery in wooden ships, 8 ; on 
 iron as a material for shipbuilding, 77 ; 
 on composite ships, 92 ; on relative 
 merits of " lap '' and " butt " joints, 
 105 ; objection by, to Mr. Daft's plan of 
 constructing iron ships, 108 
 
 " Great Britain," building of, 32 ; dock- 
 gates, &c., obliged to be enlarged for 
 launching of, 32 ; foul state of bottom 
 of, 78 
 
 " Great Eastern," "longitudinal" system 
 employed in construction of, 31 ; build- 
 ing of, 32 ; difficulties in launching of, 
 32 ; 'Times' on effects of fouling upon, 
 78 ; action of salt water on bottom of, 
 129 ; effects of fouling on, 204 
 
 Green's anti-fouling compo', 58 
 
 IRO 
 
 HALSTED (Admiral E. P.) on iron- 
 cased ships, 7 ; on the effects of the 
 
 working of the machinery in wooden 
 
 ships, 8 ; on the general use of iron for 
 
 men of war, 22; on fouling of ships' 
 
 bottoms, 62 
 Ilawksley (Mr. Thos.) C.E., on importance 
 
 of zinc sheathing, 133 
 Hay's anti-fouling composition, effects of, 
 
 67,70 - 
 Hay (Sir John D.) on action of copper to 
 
 prevent fouling, 68 ; on preserving ships' 
 
 bottoms, 196' 
 Henry VIII, method of sheathing vessels 
 
 in time of, 36 
 Holmes (Mr.) on the advantages of iron 
 
 ships over wooden ones, 13 
 
 T LLUSTRATION S of butt and lap joints, 
 1 114, 116 
 
 of Mr. Daft's plan of sheathing iron 
 
 ships, 127, 131 
 
 Improved constraction of iron ships, 39, 
 102, 204 
 
 plan of constincting ships, Mr. 
 
 Daft's, 39 
 
 " In-and-out " strake system of construct- 
 ing iron ships, 102 
 Ince and North's anti-fouling composition, 
 
 effects of, 67 
 " Indus " steamer, state of, from fouling, 
 
 57 
 Insulation, experiment for obtaining, 95 ; 
 
 difficulty of maintaining, 95 
 " Invincible " French iron-clad frigate, 
 
 state of, from fouling, 56 
 Iron as a material for shipbuilding, 12; 
 
 Dr. Fairbairn on, 19 
 bulkheads, transverse water-tight, 
 
 introduction of, 31 
 
 -clad ships, average time spent in 
 
 dock for purposes of cleaning, 60 ; pro- 
 posal to galvanise the hulls of, 128 
 
 -plated wooden ships, 8; cost of 
 
 construction of, 22 
 
 pleasure boat, the first used in salt 
 
 water, 26 
 
 ships, advantages of, over those of 
 
 wood, 13; Lloyd's rules respecting, 13 ; 
 earlier attempts at, 15; curious objec- 
 tion made by Controller of Navy to, 18 ; 
 Sir Howard Douglas's opinion of, 20 } 
 chronology of, 25 ; first record of, 25 ; 
 Richard Trevithick and Robert Dickin- ■ 
 son's patents connected with, 25 ; in- 
 troduction of transverse water-tight iron 
 bulkheads in, 31 ; designs for vessels of 
 10,000 tons and 62 guns, 33 j wood 
 
 14 
 
210 
 
 INDEX. 
 
 JEN 
 
 sheathing on, a mistake, 39 ; Mr. Mal- 
 let's opinion on the sheathing of, 47 ; 
 desiderata in, 79 ; corrosion of, 81 ; 
 improved construction of, 102 ; employ- 
 ment of dried compressed teak in con- 
 struction of, 106; zinc sheathing for, 
 78, 124; 'Standard' on corrosion of, 
 141 ; ' Standard' on the preservation of, 
 1 66 ; Captain McKillop on the preserva- 
 tion of, 172; Mr. C. F. T. Young on, 
 196 ; improved construction of, 204 
 
 JENKINS' (Mr.) enamel, failure of, 72 
 
 " John Randolph," the first iron steamer 
 
 used in America, 28 
 Jointing of plates in iron shipbuilding, 114 
 
 KANE (Dr.) on advantage of zinc sheath- 
 ing, 133 
 Kirkaldy (Mr. David) on the strength of 
 iron plates, 103 
 
 LAMPORT (Mr.) on corrosion of iron 
 ships, 90, 92, 94 j objections to Daft's 
 system, 108 
 
 " Lap " verms " butt" joints in iron ships, 
 103, 105 
 
 Lead employed in the second century as a 
 material "for sheathing, 36; galvanic ac- 
 tion of, on iron, 37 
 
 Lee's anti-fouling composition, effects of, 
 67 
 
 List of materials employed for sheathing 
 vessels, 36 
 
 Liverpool, first iron sailing-vessel built in, 
 31 
 
 Lloyd's rules respecting iron ships, 13 ; 
 classification of first iron vessel by, 34 ; 
 improvement of classification of same 
 by, 34 
 
 " Longitudinal" system of construction of 
 iron ships, introduction of, 31 ; Em- 
 ployed in building " Great Eastern," 31 
 
 MACKIE (Mr. S. J.), his paper on zinc 
 sheathing for iron ships, 156; his 
 paper on the construction and preserva- 
 tion of iron ships, 173; discussion on 
 same, 195 
 
 Mackrow (Mr.) on system of constructing 
 iron ships invented by Mr. Daft, 120 
 
 " Magicienne," application of Sir Hum- 
 phrey Davy's " protectors" to, 40 
 
 Maintenance of wooden ships of vrar, cost 
 of, 4 
 
 Mallet (Mr.) on sheathing of iron ships. 
 
 PAR 
 
 47 ; impossibility of putting metallic 
 sheets on iron ships, 47 ; on anti-foul- 
 ing compositions, 70 ; his patent anti- 
 corrosive mixture, 86 
 
 " Marine glue" for the coating of bottoms 
 of iron ships, 68 
 
 M'Connell (Mr. J. E.) patents copper 
 sheathing on iron hulls, 38 
 
 M'Innes' (Mr.) composition, failure of, 99 
 
 McKillop (Captain) on the preservation of 
 iron ships, 172 
 
 M'Laine on wooden ships of vcar, 11 
 
 Mechanical means for cleaning iron ships 
 whilst afloat, 76, 77 
 
 ' Mechanic's Magazine' on fouling of iron 
 ships, 77; on corrosion of iron ships, 
 84 ; on effects of protecting iron on 
 copper bottoms, 89 
 
 Medlock (Dr.) F. C. S. on effects of con- 
 tact of iron with copper, 89 
 
 " Megasra" iron steamer, results from ap- 
 plication of eight different anti-fouling 
 compositions to, 66; state of, from 
 fouling, 75 
 
 Mercury, application of to hulls of iron 
 ships, 86 
 
 Metallic versus non-metallic materials for 
 sheathing vessels, 37 
 
 Metals, list of, that excite electricity by 
 mutual action, 88 
 
 Milled lead, use of, in sheathing vessels, 37 
 
 " Montauk" monitor, quantity of fouling 
 matter taken from, 77 
 
 Moresby's anti-fouling composition, effects 
 of, 67 
 
 Murray (Mr.) on the salts of copper used 
 in anti-fouling compositions, 88 
 
 Mnntz's metal, its effects on the "Royal 
 Oak," 43 
 
 TUICHOLSON (Adm. Sir F. E.), copper 
 
 •L' on iron ships, 49 
 
 Noad (Dr. H. M.) on the action of sea-water 
 on compounds containing copper, 89 
 
 Normandy (Dr.) F. C. S. on the decom- 
 position of sails of copper in contact 
 with iron, 89 
 
 
 
 UR national defences, 141, 159 
 
 PAGET (Lord Clarence), fouling of iron 
 ships, 53 
 Pakington (Sir John) on fouling of iron 
 
 ships, 76 
 Paris (Admiral) on fouling of iron ships, 76 
 Parker's anti-fouling composition, effects 
 of, 67 
 
INDEX. 
 
 211 
 
 PAT 
 
 Patents for modes of sheathing vessels, 
 various, 37 
 
 Peninsular and Oriental Company, super- 
 intendent of, at Bombay, on fouling, 57 
 
 Percy (Dr.) on action of zinc sheathing, 133 
 
 " PlicEiiix," photograph of barnacles taken 
 from brass screw propeller of, 69 
 
 " Poisoning" process, 69 
 
 Portsmouth Dockyard, experiments on zinc 
 sheathing for iron ships, 124 
 
 Prejudices of shipbuilders, &c., against iron 
 ships, 20 
 
 " Prince Consort," straining of, in gale, 9 
 
 sheathed with copper, 99 
 
 Proposal to build docks on distant stations 
 for cleaning men-of-war, 74 
 
 RADERMA.CHER (M.) on the action of 
 iron and copper in sea-water, 88 
 Rae (Mr.) on galvanic action, 85 
 Rankine (Professor) on action of zinc 
 
 sheathing, 133 
 Rapidity with which iron, when exposed to 
 
 sea-water, fouls and corrodes, 22 
 Reed (Mr. E. J.) on the conversion of our 
 
 existing wooden fleet into iron-clads, 9 j 
 
 on the construction of iron ships, 193 
 Report of committee on dockyards and 
 
 basin accommodation, 74 
 Requisites to be looked for in a vessel by a 
 
 shipowner or merchant, 73 
 " Resistance," cost of construction of, 23 
 Ritchie (Mr. J. H.) on the advantages of 
 
 iron over wood in shipbuilding, 14 
 Robinson (Mr. W. B.) on the effects of the 
 
 working of screw machinery in wooden 
 
 ships, 8 
 Royal Navy, first iron steamer built for, 
 
 31 ; effects of copper sheathing on ships 
 
 of, 43 
 "Royal Oak," effects of corrosion on, 95, 
 
 98 
 Roux (M.), his plan for applying copper 
 
 sheathing to vessels, 44 ; experiments 
 
 connected with, 45; insufSciency of, 46 
 
 ' SCIENTIFIC AMERICAN ' on wooden 
 •^'armour-plated ships, 10 
 
 Scotland, first iron sailing vessel built in, 
 31 
 
 Scott Russell ( Mr.) on the effects of the 
 working of screw engines in wooden 
 ships, 8; on the prejudices of ship- 
 builders, &c., against iron ships, 20 ; 
 employs "longitudinal" system of con- 
 struction in " Great Eastern," 31 ; on 
 the merit of copper sheathing, 48, 90 
 
 VAL 
 
 Secretary of Admiralty (the late) on fouling 
 of iron ships, 76 
 
 of the American Navy on armour- 
 plated wooden ships, 10 
 
 Seely (Mr. C), M.P., on the cost of our 
 wooden ships, 3 
 
 Selwyn (Captain J. H.) on corrosion in 
 the water of the tropics, 82 j on galvanic 
 action induced by contact of copper 
 with iron, 96 
 
 Sheathing of vessels, materials employed in, 
 36 ; method of, in time of Henry VIII, 
 36 ; in time of Charles II, 37 ; use of 
 milled lead in, 37 ; various patents for 
 modes of, 37 ; metallic versus non- 
 metallic materials for, 37 ; zinc as a 
 material for, 40 ; copper as a material 
 for, 40 
 
 Shipbuilding, wood as a material for, 1 ; 
 iron as a material for, 12; iron steadily 
 displacing wood for, 23 ; zinc as material 
 for, 129 
 
 Ships, Wooden, 1 ; " composite," 5 j 
 armour-plated wooden, 8 ; iron, 12 
 
 " Spencer" wooden ship, comparative cost 
 of building and maintenance of, 4 
 
 'Standard' on corrosion of iron ships, 
 141 ; on zinc sheathing for iron ships, 
 149 ; on the construction of iron ships, 
 169 
 
 ' Steam Shipping Journal ' on corrosion of 
 iron ships, 94 
 
 " Superb " wooden ship, comparative cost 
 of building and maintenance of, 4 
 
 " Supply," state of, from fouUng, 203 
 
 Szerelmy (Mr.), composition, failure of, 62 
 
 " mAUREAU " French iron-clad, state of, 
 J- from fouling, 56 
 
 Teak, employment of dried compressed, in 
 construction of iron ships, 106 ; advan- 
 tage over oak. 111 ; method of compress- 
 ing, 119 
 
 ' Temple Bar ' on the disadvantages of 
 wood for screw shi ps of war, 7 
 
 Timber, difficulty of obtaining suitable, for 
 building wooden ships, 2 
 
 Transverse water-tight iron bulkheads in 
 iron steamships, introduction of, 31 
 
 Trevithick (Richard) and Robert Dickin- 
 son, their patents for inventions con- 
 nected with iron ships, 25 
 
 " Triton," effects of corrosion on, 99 
 
 " Y^LIANT," result of eighteen months' 
 V trial of " anti-fouling" compositions 
 on, 71 
 
212 
 
 INDEX. 
 
 VAR 
 
 Various attempts at attaching metal sheath- 
 ing to iron ships, 47 
 
 Vessels with iron hulls, cased with wood, 
 and sheathed with copper or yellow- 
 metal, 49 
 
 Voyage of the " Aaron Manby" iron steam- 
 boat from London to Paris, 26 
 
 " Vulcan " passenger iron vessel, 26 
 
 WALL'S (Mr. A.) patent for application 
 of mercury to hulls of iron ships, 86 
 
 Want of attention to chemical action of 
 metals in contact with sea-water, 40 ; 
 analysis of the subject, 41 
 
 "Warrior," cost of construction of, 23; 
 the first iron-plated ship, 33 ; dimensions 
 of, 33 ; state of bottom of, upon being 
 taken into dock, 59 
 
 Water-tight transverse bulkheads in 
 wooden ships, introduction of, 31 
 
 Wheelwright (Mr.) introduces "longitu- 
 dinal" system of construction of iron 
 ships, 31 ; carried to perfection by Mr. 
 Scott Russell, 31 
 
 Wilson (Professor) on "poisoning" pro- 
 cess, 69 
 
 Winter not the proper time for testing 
 anti-fouling compositions, 79 
 
 WoUaston (Dr.) on galvanic action of zinc 
 and copper, 97 
 
 Wood as a material for shipbuilding, dis- 
 advantages of, 1 
 
 sheathing, 39, 87 
 
 Wooden ships, 1 ; difiSculty of procuring 
 material for, 2 ; delays in the construc- 
 tion of, 2 ; absorption of water by, 3 ; 
 costliness of, 3 ; use of iron in, 5 ; weak- 
 ness of large, 7 ; Mr. Scott Russell on, 
 7 ; Admiral E, P. Halsted on iron-cased. 
 
 ZOO 
 
 7 i eflTects of working of machinery in, 
 7; Mr. Grantham on, 8; Mr. W. B. 
 Robinson on, 8 ; Mr. £. J. Reed on the 
 conversion of, into iron-clads, 9 ; Secre- 
 tary of American Navy on iron-plated, 
 10 ; ' Scientific American,' the, on ar- 
 mour-plated, 10 ; case of the " Amazon," 
 10 ; Captain C. P. Coles on wooden 
 men-of-war, 11 ; Mr. A. M'Laine on, 11 ; 
 introduction of transverse water-tight 
 bulkheads in, 31 ; iron-cased floating bat- 
 teries introduced by Emperor of the 
 French during Crimean war, 33 
 
 YELLOW-METAL sheathing, action of 
 sea-water on, 40 
 Young (Mr. C. F. T.) on fouling of ships' 
 bottoms, 196 
 
 " y EALOUS," plan of sheathing of, 47 
 
 Zinc as a material for sheathing ships' 
 bottoms, 40; objections made to, 38-; 
 as a substitute for iron in shipbuilding, 
 129 
 
 sheathing on iron ships, 78, 100 ; 
 
 mode of applying to existing iron ships, 
 131 ; Dr. Percy on action of, 133; Prof. 
 Rankine on, 133 ; Professor Graham on, 
 133; Professor Brande on, 133; Pro- 
 fessor Grace Calvert on, 134 ; Dr. Fair- 
 bairn on, 135; Admiral Halsted on, 
 135; 'Standard' on, 149; 'Engineer- 
 ing' on, 154 ; Mr. S. J. Mackie on, 156; 
 
 Zoophytes on ships' bottoms, supposed 
 poisoning process of copper on, 42 ; 
 opinion held by Sir Humphrey Davy, 
 42 ; fallacy of, 43. 
 
 PaiNTKD BI THE LOHDOH DE4WIN0 ASSOCIATION. 
 
THE 
 
 LONDON DRAWING ASSOCIATION, 
 
 7, DUKE STREET, ADELPHI, W.C, 
 
 CM anir Pe^aniral d^ngiiteers, graftsmen,. 
 
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 From all the members being thoroughly practical men, and 
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 receipt of one stamp, to any address. 
 
 Established February, 1862. 
 
SUPPLIED BY THE LONDON DRAWING ASSOCIATION, 
 
 7, DUKE STREET, ADELPHI. 
 
 In One Vol., post 8vo, cloth, 421 pages, with 21 Wood Engravings, and One 
 large Folding Sheet, 
 
 THE 
 
 ECONOMY OF STEAM POWER 
 
 ON 
 
 COMMON ROADS, 
 
 IN BBtATION TO 
 
 AGRICULTURISTS, RAILWAY COMPANIES, MINE AND COAL 
 OWNERS, QUARRY PROPRIETORS, CONTRACTORS, &c. ; 
 
 ■WITH ITS 
 
 HISTORY AND PRACTICE IN GREAT BRITAIN. 
 
 CHAS. P. T. YOUNG, O.E., 
 
 HEM. BOO. ENalNEEBS ; ASSOC. I.N.A. 
 AND 
 
 ITS PROGRESS IN THE UNITED STATES. 
 
 BY 
 
 ALEX. L. HOLLEY, C.E., and J. K. FISHER, Engineee, 
 NEW YORK, U.S.A, 
 
 1860. 
 
 Forwarded post free, on receipt of Post-Offioe Order for 12s. 6d., payable to 
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 BBB OPINIONS as THE PEESS ON OTHEE SIDE. 
 
OPINIONS OF THE PRESS. 
 
 " Mr. Young's work, apart from its merits as an able exposition of the scientific 
 views of the subject of which it treats, possesses very considerable interest for the 
 general reader." — Atlas. 
 
 "We cordially commend the book before us to our readers as a highly useful 
 treatise on a highly important subject." — Engineer. 
 
 " One of the most interesting treatises upon a purely scientific subject which we 
 have ever met with. We doubt not that, public attention once thoroughly aroused. 
 Brother Young will not be long in again coming before us with fresh arguments and 
 illustrations, pleasantly put together, as in the present volume." — Freemason's 
 Magazine. 
 
 " We recommend the book to all interested in its special subject, containing as it 
 does a large amount of information laboriously collected, and the publication of which 
 at this moment is particularly opportune." — Civil Engineer and Architect's Journal. 
 
 " One of the most interesting and practical works we have for a long time seen. 
 It gives us great pleasure to commend Mr. Young's work to the serious attention of 
 our readers, as being plain, practical, and highly instructive." — Artizan. 
 
 " Evidence is abundantly supplied in the pages of Mr. Young's interesting and con- 
 cise work, that the wear and tear of roads by steam carriages would be less than by 
 the horse traffic of the present day. Whoever doubts had better send off at once for 
 a copy of the treatise on the ' Economy of Steam Power on Common Roads.' " — City 
 
 " The very interesting volume of Mr. Young, which is the first of its order, at least 
 for five-and-twenty years. Mr. Young's book is a very timely one, and, so far as we 
 have noticed, does fair justice to the subject, and is ably written, forming an interest- 
 ing as well as important volume at the present moment." — Suilder. 
 
 " The whole question of steam locomotion is very fully discussed, with a keen per- 
 ception of the requirements of the present age, and a no less intimate acquaintance 
 with the history of the subject. We are unable within our limits to give an adequate 
 idea of the contents of Mr. Young's book j but we have said enough to direct atten- 
 tion to a work which, to use a stereotyped phrase, should be in the hands of all inte- 
 rested in the subject of which it treats." — Suilding Sews. 
 
 " A valuable illustrated work has just issued from the press treating the question 
 ably in all its bearings, and furnishing an interesting history of the practical applica- 
 tion of steam to ordinary road traffic. Should a decided movement for practical 
 application at any time henceforward result, the author of this interesting and ad- 
 mirable work may congratulate himself on being the medium for its inauguration; 
 and in reward for his laudably directed labour and ability, independent of the boon 
 derivable therefrom by the public, we earnestly hope for a successful consummation." 
 — Dnllin Builder. 
 
SUPPLIED BY THE LONDON DRAWING ASSOCIATION, 
 
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 In One Vol., demy 8to, cloth, 534 pages, with Sixty-seven Wood Engravings, 
 and Two large Folding Lithographs. 
 
 FIEES, EIEE ENGINES, & FIRE BRIGADES, 
 
 A HISTOET OF MANUAL AND STEAM FIRE ENGINES, 
 
 THEIR CONSTRUCTION, USE, AND MANAGEMENT; 
 
 EEMABKS ON riBE-PROOP BTTILDINGS, AND THE PEESEBVATION OP LITE PEOM PIKE ; 
 
 STATISTICS OP THE PIEE APPLIANCES IN ENGLISH TOWNS ; POBEIGN PIBE 
 
 SYSTEMS ; HINTS POE THE FORMATION OP, AND EULES FOE PIBE 
 
 BEIGADES ; BEMAEKS ON AND STATISTICS OF THE 
 
 VOLUNTEEE PIEE SYSTEM ; AND AN ACCOUNT 
 
 OP AMERICAN STEAM PIRE ENGINES. 
 
 CHAS. r. T. YOUNG, O.E., 
 
 MEM. SOC. ENGINEEBS ; ASSOC. I.K.A. ; 
 
 AUTHOR or 
 
 *THK ECONOMY 01" STEAM POWER ON COjIMOH ROADS;* 'THE BEST MODE Of 
 PROTECTINO LONDON FROM THE RAVAGES OE FIRE.' 
 
 1866. 
 
 Fonttorded post free, on receipt of a Poat-Office Order for 2418., payable to Fbbdebio 
 YouNa, at the Post-Qffice, Charing Cross, London. 
 
 SEE OPINIONS OP THE PEBSS ON THE OTHER SIDE. 
 
OPINIONS OF THE PRESS. 
 
 " A large well-fiUed and useful book upon a subject which possesses a wide and 
 increasing public interest. It gives the most complete account ever written of the 
 history, introduction, and construction of steam fire-engines. It is really the only 
 English work we now have upon the s\xhiect." ^Engineering. 
 
 " A volume which must be regarded as the text-book of its subject. The style of 
 the work is admu'able. It has the surpassing merit of beiiig thoroughly reliable." — 
 Insurance Mecord. 
 
 " Mr. Young's valuable work, a copy of which ought to be in the hands of every 
 Fire Insurance Agent." — Post Magazine. 
 
 " Mr. Young's excellent book." — AtTienceum. 
 
 "Mr. Young has produced a really exhaustive work. The reputation of Mr. 
 Young (who is the author of the ' Economy of Steam Power on Common Roads,' &c.) 
 will certainly not suffer from the production of the present volume." — City Press. 
 
 " A work which is an important addition to the history of Mechanical Engineering 
 in the present day, and the observations which he has made respecting fire-engines 
 and their uses will give him an additional claim to be regarded as a most pains- 
 taking compiler of facts, and as an intelligent and careful observer upon any subject 
 which he takes in hand." — Observer. 
 
 " Mr. Young's book is in every way entitled to be closely studied by all who would 
 claim anything approaching a thorough knowledge of the subject." — Mining Journal. 
 
 " We recommend this work, as it concerns everybody, to everybody's perusal." — 
 Court Journal. 
 
 " Mr. Young deserves hearty thanks for the elaborate pains, benevolent spirit, 
 scientific knowledge, and lucid exposition he has brought to bear on this subject ; 
 and his substantial book should meet with substantial success : for it concerns every- 
 one who has even a skin which is not fireproof." — Illustrated London News. 
 
 " The author of this work is evidently a man thoroughly conversant with fire- 
 engines and fire-brigades, and indeed the whole history and arcana of steam and fire- 
 engines ; and their proper management and construction have been laid open in the 
 pages before us." — Colliery Guardian. 
 
 " It may be called a useful compendium on all branches of the exciting subject of 
 fire." — Suilder. 
 
 " Mr. Young's book will take its place in bur literature as a standard history of 
 manual and steam fire-engines, and will be universally referred to for the statistics 
 of fire-appliances, and the means of preserving life and property. Mr. Young may 
 well 'he congratulated on the good reputation his book is sure to obtain, as the 
 
 15 
 
recognised manual of reference and consultation upon all that concerns fires, fire- 
 engines, and fire-brigades, and the practical details and statistics of these subjects." — 
 /Standard. 
 
 " Mr. Young's work, which is written throughout with an evident desire to throw 
 a clear light upon what has hitherto been but an imperfectly understood subject, 
 commences with a chapter upon ' Fires ' generally, and hints most excellent in cha- 
 racter for their prevention. This is followed by instances of large conflagrations. We 
 then have an excellent chapter on ' Fire Brigades,' followed by others on ' Subduing 
 Fires,' 'Fireproof Structures,' 'Manual Engines,' 'Steam Fire-engines,' 'Trials,' &c. 
 We cannot enter at length into a discussion of all the features of Mr. Toung's work, 
 which touches upon almost every detail of fires and their prevention, showing not only 
 what has been done in our own country, but in other parts of the world, and giving 
 numerous suggestions which can only have arisen from a careful consideration of the 
 subject, and a sincere desire to advance the ends of truth. To all those who may 
 feel an interest in a subject of such importance to us all, we cannot do better than 
 recommend an attentive perusal of this laborious work, which we feel assured will 
 direct attention to many points of importance not hitherto either properly understood 
 or fairly appreciated." — Civil Engineer and Architect's Journal. 
 
 "Mt. Young has proved by his present work that he is a good engineer and pos- 
 sessed of sufficient literary skill and energy to produce a very readable and interesting 
 volume." — Engineer. 
 
 " Mr. Young's book is thoroughly practical." — Seader. 
 
 " He is evidently in earnest in dealing with his subject, and has taken great pains 
 to collect information of every kind, and from every quarter, in connection with it." 
 — Spectator. 
 
 " If Dr. Sestier or his editor warns us that the fires caused by lightning • are 
 generally remarkable for their rapidity and violence,' Mr. Young will tell us of the 
 best methods of constructing engines and organising brigades of firemen to put them 
 out ; and it will astonish many of our readers to find how much interesting matter 
 can be brought together on such a subject. Mr. Young strongly maintains the neces- 
 sity of greatly increased fire-subduing force in this country, and especially in our 
 larger towns and cities, and expresses himself in favour of the volunteer principle in 
 forming brigades." — T/ie Westminster and Foreign Quarterly Review.