» Digitized by the Internet Archive in 2016 https://archive.org/details/forthbridgeOOwest PLATE I. From a photo jraph by the London Stereoscopic Company. PLATE II, From a photograph bg Baisano. ! Feb. 28, 1890.] ENGINEERING. 213 THE Historical. It has at all times been a subject for contro- versy and a matter of difficulty to fix the precise boundary line between the river and the sea, that is to say exactly where the sea ends and the river commences. With regard to the Forth and its estuary, the same discussion has been carried on in Parliament and elsewhere with considerable warmth, but does not appear at the present moment to have got any nearer to settlement than in 1882. Taking, however, a point, say Anstruther, in Fife- shire, and another, say Dunbar, in Haddington- shire, and drawing a line across which, rougldy speaking, passes near the May Island and the Bass Rock, we may call it the Forth within and the sea without this imaginary boundary line. Starting westward from it we have 32 miles to Queensferry and 30 miles further to Stirling. On both sides of this great watershed are situated hundreds of square miles of some of the most fertile and best cultivated laud in the three kingdoms. There are great coal- fields, there is mineral wealth and, besides, an im- mense supply of food and other commodities which the inhabitants of these districts would wish to ex- change or barter. But a serious barrier stood in the way, and stands even to this day, for the only means of intercommunication and of transport be- tween the two shores is afforded by steam ferries or by sailing craft. Of the former there are three ; the most seaward is that from Granton to Burnt- island, five miles long, and 24 miles up the Forth ; the next is that between South and North Queens- ferry, 32 miles from the boundary line ; and the third at Kincardine, about 15 miles west of Queens- ferry. The first bridge for railway traffic is at Alloa, 20 nnles from Queensferry, and the next at Stirling. The Granton-Burntisland passage (see map on the next page) is seriously affected by the weather in the winter months, is often impassable during strong gales, andatthebestof timesthe disembarkation from train to boat and from boat to train is a source of con- siderable discomfort to passengers, and what is worse a great waste of time. The same holds good, though in a minor degree, at Queensferry .and at Kincardine, and the traveller who requires to go from Dunbar to Anstruther, to put an extreme case, and who objects to either of the sea passages, has no choice left him but to go round by Alloa or Stirling, and to pass over about 150 miles of railroad, when the distance between the two towns mentioned is, as the crow flies, less than 18 miles. That under such conditions the commercial and agricultural inter- course and traffic between the eastern counties of Scotland suffered a serious check, and became reduced to a minimum, was but to be expected. The same disadvantages existed in the case of all those travellers, bent on business or on pleasure, from north to south or vice versa, who desired to pass through Edinburgh on their way, and who had either to cross by one of the ferries or make the long detour by Stirling, being in either case compelled to submit to a loss of valuable time. Finally, the principal railway companies whose systems are situated in the eastern and midland counties of England and the south of Scotland, could get no access to the northern parts of Scotland except by passing over the lines of a company whose interests were hostile and in opposition to their own. This brought about a most intolerable state of things, and is an easy FORTH BR By \Y. WESTHOFEN. explanation of the many struggles and attempts made by the East Coast lines to obtain a separate access to the counties north of the Forth. How great the necessity was of having means of com- munication between the two shores, and how largely even the inadequate provisions made hitherto were taken advantage of, is proved by the fact that in 1805 — before a steamboat existed or a railroad was thought of — the right of running ferryboats between South and North Queensferry was let at a yearly rental of 2000k, and it is stated in the Parliamentary evidence then taken that the revenue derived by outsiders who run goods and passengers across in yawls and small boats amounted to fully 5000k per annum in addition. It must be admitted that the F orth Bridge crosses the river at a point which leaves the eastern counties still somewhat in the same difficulty, but it reduces many of the local distances to be traversed by more than one-half, and the gain in time is con- siderable. Going by the Forth Bridge and its connecting lines the traveller will now be carried to and safely landed at Perth, Dundee, or Aberdeen, as the case may be, in a comparatively short time after leaving Edinburgh — in one and a quarter hours, one and three-quarter hours, and four hours respectively — independent of wind or tide and without difficulty and discomfort. In speaking of the new lines in connection with the bridge this matter will be further referred to. The justification for the construction of so great a work must, however, be sought in the desire to serve larger interests than those of local traffic merely. In these days of high pressure, of living and working and eating and drinking at top speed, the saving of an hour or two for thousands of struggling men every day is a point of the greatest importance, and every delay, however excusable and unavoidable, is fatal to enterprise. Nor must the bridge be looked upon as a thing standing by itself, but rather as a portion — certainly a some- what expensive portion — of a gigantic system of railway lines converging from all directions upon the capital of Scotland, affording means not only of more speedy and more comfortable travelling, butalso giving facilities for the provision of a larger number of those through trains which are constantly be- coming more necessary by the yearly addition of many miles of both main lines and branch lines. Altogether those concerned in this great undertak- ing are sanguine that within a very few months the courage, the foresight, and the wisdom of the directors of the Forth Bridge Railway Company, and of the other interested railway systems, will be fully proved by results which it is impossible to estimate even approximately just now. When and with whom the idea of bridging the Forth first originated is now a matter of pure con- jecture. The Roman leader bent on exploration and conquest, probably conjured up in his mind’s eye the faint outlines of a bridge as he trudged the weary miles along the south shore and found neither boats to carry him across nor ford to traverse — so must often have the sainted Margaret, the wife of Malcolm Caen-Mohr, on her frequent pious pilgri- mages between Edinburgh* Linlithgow, and Dun- fermline about the time of the Norman Conquest, and so probably her son Alexander the First of Scotland, who in attempting to cross from South to North Queensferry was overtaken by a gale and I DGE. beaten down the Firth, and had finally to land on the island of Inchcolm, five miles away. He founded a priory on that island as a thanksoffering to Providence for a very narrow escape and in view of a warmer reception and more substantial enter- tainment should a similar misfortune again befall him. So must also many of the poor wayfarers who got drenched to the skin and suffered the horrors of sea-sickness during the crossing, and so must finally — if there was time for them to do so — the unfortunate party of people who were driven down the Hawes Brae at so rapid a pace that horses, carriage, and passengers went right off the pier into the water and none of them came out alive. The idea thus floated through many minds until about 150 years ago, when a bridge was first spoken of, but particulars as to design, site, or probable cost do not seem obtainable. In November, 1805, a proposal was made to con- struct a double tunnel — 15 ft. wide and about the same in height — quaintly described as one for comers and one for goers — under the bed of the Forth, at some point to the west of Queensferry. The project was evidently seriously entertained, fer in July, 1800, a prospectus was issued by “a number of noblemen and gentlemen of the first respect; - bility and scientific character,” inviting the pubi c to subscribe — the shares being fixed at 100k each. Further, in 1807, a pamphlet of about 120 pages was published in Edinburgh, entitled “Observatioi s on the Advantages and Practicability of making Tunnels under Navigable Rivers — applicable to the proposed Tunnel under the Forth. Illustrated with a section and map.” Nothing, however, seems to have come of the project, whether owing to diffi- culties of construction or of financing is not known — most probably both. Within eleven years another effort was made, and we come upon a pamphlet entitled “ Report relative to a Design for a Chain Bridge thrown over the Firth of Forth at Queensferry By James Anderson, civil engineer and surveyor, Edinburgh, 1818.” There were three elevations, differing as to height and length of clear span, but all equally bold and equally primitive; we give on the next page but one a reproduction on a smaller scale of the diagrams accompanying this report. The site was to have been nearly the same as that of the present bridge, starting from the same point at North Queensferry, passing very nearly over the centre of Inchgarvie, and terminating on the south shore about one-third of a mile east of the Hawes Pier, joining the Edinburgh Road just under Mons Hill. The clear height above high water was to have been either 90 ft. or 110 ft., the main spans 1500 or 2000 ft., the width for carriage road and footpath 33 ft., and the cost 175,000k or 205,000k The time required for com- pletion was stated to be four years. A revenue of 10 per cent, on the capital expended was considered a very moderate estimate, which proves that the art of writing a highly coloured prospectus is of older date than most people would have thought. To judge by the estimate the designer can hardly have intended to put more than from 2000 to 2500 tons of iron into the bridge, and this quantity distributed over the length would have given the structure a very light and slender appearance, so light indeed that on a dull day it would hardly have been visible, and after a heavy gale probably no longer to be seen on a clear day either. 2 I 4 ENGINE E RING. [Feb. 28, 1890. This scheme also proved abortive, and for forty years more the travelling public put up with what they could get, but at last in 1860 the North British Railway fixed upon a site about six miles to the west of South Queensferry as suitable for the con- struction of a railway bridge. The bridge was to have consisted of a number of large spans of 500 ft. each in the centre, with approaches in shorter spans at either end. The exact centre line was to have been from a point near Blackness Castle on the south shore to Charleston on the north shore, and connecting lines from near Linlithgow, on the dredgers to keep a channel clear, although the ferry steamer draws little more than 4i ft. of water. These conditions are a source of much discomfort to the passengers by this route — for the light draught steamer can hardly hold its own against a gale of wind broadside on, and many people become sea- sick during a passage lasting at the worst of times barely twenty minutes. In 1873 the Forth Bridge Company was formed for the purpose of carrying out the design by Sir Thomas Bouch of a suspension bridge with two large spans of 1G00 ft. each. The capital was side. The piers at Queensferry and on Fife were very nearly in the same position as those of the present bridge, and there were two approach viaducts to reach the high ground upon either side. The bridge was to have been constructed entirely of steel. Offices and workshops — which are now standing — were built at Queensferry, and extensive brick- works near Inverkeithing laid out and started. A brick pier — one of eight, which were to form the base of the great Inchgarvie tower — was built at the extreme north-west corner, after a foundation Edinburgh and Glasgow line on the one side, and from Charleston to Dunfermline on the other side, would no doubt have established a very good through line to the north. Borings were taken and other ! investigations made. A design had been drawn out by Sir Thomas (then Mr. ) Bouch, and Parliamentary powers for the construction of the bridge were obtained by an Act in 1865. The river here is about 2J- miles wide, and the greatest depth of water about GO ft. — but the bottom is loose and uncertain, and it was decided to build up and sink an experimental pier before proceeding further. But troubles inter- vened, and during the re-arrangement of the North British Railway Company in 1866-18G7, the project was abandoned through various causes. F or it were substituted improvements in the Queensferry passage by the construction of the railway slips at North Queensferry and Port Edgar. It was at first intended to have swinging landing-stages at each end, rising and falling with the tide — the trains by means of these to be run on and off the ferry steamers. The latter portion of the scheme was not carried out however, owing to the insufficient depth of water and the gradual silting up near the piers, which necessitates the periodical assistance of raised by the four principal railway companies interested in the East Coast traffic — namely, the Great Northern, the North-Eastern, the Midland, and the North-British, and the companies came to an understanding among themselves that they would between them send so much traffic across the bridge as would suffice to pay a dividend of 6 per cent, per annum on the contract sum. The Act authorising the construction of the bridge was passed in the same year, 1873, and a contract signed with Messrs. W. Arrol and Co. , of Glasgow. An illus- tration showing elevation and plan of Sir Thomas Bouch’s design is shown in Fig. 2. The central towers from which the main chains are suspended were to have been 550 ft. above high water, while the rail level would be at such height as to leave a clear head-room of 150 ft. above high water between the piers. The central tower on Inchgarvie was over 500 ft. long, which brought the foundations upon the sloping rock down to a depth of over 110 ft. below high water. There were two lines of rails carried at a distance of 100 ft. from each other, each line being supported on a pair of strong lattice girders, and these were laterally stiffened by single diagonal bracings reaching from side to stone had been laid with great ceremony. But the collapse of the ill-fated Tay Bridge in December, 1879, stopped the further progress of the work, and the investigations into the causes of that disaster, and the disclosures ''made, shook the public confidence in Sir Thomas Bouch’s design, and rendered a thorough reconsideration of the whole subject necessary. As a first result of this, the suspension bridge was abandoned, and the four railway companies above named instructed their consulting engineers — Messrs. Barlow, Harrison, and Fowler — to meet and consider the feasibility of building a bridge for railway purposes across the Forth, and assuming the feasibility to be proved, to decide what description of bridge it would be most desirable to adopt. It was fairly well known how many types of bridge there were to select from for such a site ; these were (1) Mr. Bouch’s original design (Fig. 2) ; (2) three forms of sus- pension bridges with stiffening guides and braced chains (Fig. 3) ; and (3) a cantilever bridge (Fig. 4). The inquiry was most comprehensive. It embraced ! not only bridges as set forth, but also tunnels, and I both of these for different sites. With regard to tunnels, it was considered that Feb. 28, 189c.] the great depth of water in the two main channels — above 200 ft. — and the high ground upon both shores, would necessitate very steep gradients and long approaches — making the tunnel many miles long, irrespective of the uncertainty of the nature ENGINEERING. expedient to construct a bridge with shorter spans than those which are indicated by the natural con- figuration of the ground. The original design for a continuous girder bridge (see Fig. 4) — on the cantilever and central girder finally adopted, and Messrs. Fowler and Baker were appointed engineers to carry it into execution. In July, 1882, an Act of Parliament was obtained, authorising the construction of the bridge, and sanc- tioning the new financial arrangement by which the Stretch i Machine, nch Garvie 'ROUND PI AN Of me BRIDGE Garvie lslan< Southern Abutment lem Abutment north queensfekry WGarvic Island Foundation luFeet under Low Watej PlUARt Superintendent & mjjuse Newhalls Pier or, Landing Place/ , Newhcdls Inn ■H QUEENSFERRY Transverse Elevation of a Pillar Ground Plan m LONGITUDINAL SECTION. Southern Abutment Fig. 1. Anderson’s design for bridge over, the forth, 1818. Northern Abutment 3838 A of the ground through which the tunnel would have to be cut. All things considered, the most suitable site for a bridge was held to he that at Queensferry ; and, owing to the great depth of water and the nature of the bottom of the estuary, it was not considered I principle which had been submitted by Messrs. F owler and Baker — was in some particulars modified j to suit the conflicting views of the other consulting engineers, and was then submitted to the directors in May, 1881. After consultation with the officers [ of the Board of Trade, this design (see Fig. 5) was capital ol the F ortli Bridge Company was guaranteed with interest at 4 per cent, per annum, each of the four contracting railway companies undertaking to find its share of the capital expenditure and pay its share of the interest. It is also agreed that the North British Railway Company will maintain the per- 2 1 6 ENGINEERING [Feb. 28, 1890. THE FORTH BRIDGE, CANTILEVER TYPE; ORIGINAL AND FINAL DESIGNS. MESSRS. HARRISON, BARLOW, FOWLER, AND BAKER, ENGINEERS. Feb. 28, 1890.] ENGINEERING. 2 1 7 o r-X ! -t-3 0 » 68 r-O ,K' 0 ce 0 O O u § w -b b o 0 £ £ bD b O ^ 5 '-b 05 'g b A ce 5 9 4J W r ■g £ -g f r-J CD .'r 0 JH^KCOO)- Q fl ^ h CQ J 0 g -b .g ■ rH ' ■ H « bD 02 £ 08 ° .JfA g oOPo2C'l r ' : OcZ2-b02 53 p th . ^ 02 CD ffi +3 ts b o ce 02 C'l ■ O'! rA C'-J 5 A •5 &> 2 £ rH^l bD .2 PP „ o b ce CD r 1 a b r 7‘ l oV O $ g 2 S 14 s ® i2 bD^ ~ ° a .t o bi)S - g d -g 1-1 ^ q 5 ^2 .r^ o ^ ^ c CD 3 ® ar bo rS ■d £ - 0 © ° o ?*— Sr— 2 lH 5 jj * S'S ° -^^r-s^roSPejce a, »ooo$2 2^ a «S.2 rp pL, © m m r*^ ' 02 CD 02 1- ""* bD b LO b ° 02 o (M ce H ^ o lo : 00 *? b/D C , , ^ O 02 . P 2 I ^ 02 .b ' "cC ^ ft 02 F ^ ' ’ 02 ,>i O r? !h 02 ce c ib o ce ^ t oj p ^ ^ 5o 02 p 7 ^ 02 o S -2 r ce s 02 02 o ^ ^ Db 02 02 _bp^ E 1 o 02 - 02 f>j 02 ^-43 — < ^ ' C < — < I-* p_, ce o ■ 02 02 k S' 02 .g 02 qb ;> 02 bJD 02 -P 5 ^ b r r r^io r M- r “ ! ^ 02 4^^ | 0 o : ' 02 02 02 1 n 5 g ^ r! n o X o g b/D 02 02 l CO , 8 ^ p 4-t . o k* - O 02 b/D 02 02 • 0 ce 'b 02 " 02 bp £ ■S § >lii Mr |- ^ "»'E 68 g bT b ^ p r Sai’s§l§l £: 5 S S ® i b/D vr , b o ^ I p C2 0 02 b/D 68 fcj -g h02 ■ .gd-^^ 02 £5 ce gb/D* r P '02 .?. _ X A3 b/D G) pp .-** uj 1 ^, O r*~a C-i -...„ . ^ ^ O ^ Ph b/D Q 2 a^ oogr-Pce^PnOrrtg 943 • Cli P 02 -4-3 ^ 0 o g b 0 0 r -P H b CC 02 bi" ^' - ^ CD "bi : b-rHO gfieShM^^S'SflS 3 ^ lA'S - ^ I 15 '" g - 0 ^ 02 M O PP g -g • PH rd 02 . J « 0 0 O 0 02 T 0 ; b/D 0 0 0 4H ■ "a, 0 02 ^ S 'gW. ! CO I t*i 10 lo ^ 00 43 , ,q ; o ce : H £l 02 g 'r b/D. 02 0 0 # n O 0 b/DA^ oT' o 0 b P s O O p ^ g 0 7 : b ^ o o ^ | 43 o 0 1 .4U .3 02 r* 0 J ■£ g 0 ^ H 0 1e © bc — 02 .b P P b rA b-2 P 3 cd " rH 5e >4 > b/DrL r- JP g 02 b O , ^ 0 0 0 0 bP ’b/D bD ; r-i 0 .3 g ^ 4 h r-.S S ° 0 b/D g b "2 0'4‘5 !r20 g - 02 -— ; 02 ' ■ 2 A pH 02 02 CD ^ b A o 02 0 0 02 ce 0 b O b ^ cq o >: oq 0 » ce - 4-3 !q 02 -4-3 go ce ce h b/D o 0 r ■h ^ 43 • g 0 0 02 b/D* b/D ce 02 h b r /)b rb>f- o p 02 • b bD A 0 : Pq 1 0 hPrb o b 0 rX £ is a? pq o &JD “ pj ^ |f 8S - b a J b2 b -r- , 0 *b 50 S-S § 3=! 'rt j e [c . . _ - n, e. 0 O GO o bD o A bD , 0 o ce 1 ce 0 0 0 1 ^ ^ .bp 0 g P ^0 M 2 t A ceP5 §1 b g ^ c g - b 0 *• b s - 5 1 . ^ ft r bo o c • Pq ' 02 P b 0 . < g ce ce bD < bD m 1 0 Kf^r— ( 43 b-t c c H g g; C2 O 0 02 b O <-1 0 0 43 0 g , 43 02 b 43 02 02 ^ b 0 0 , O g : bD g 02 ce V3 -x .2 CL ® 34 b ^ 0 ce 1/2 ^ 0 A CD ,p- kA ^ p ^ 02 CO g 44 .j- IN pl *3 j A CO O ' o co ib, l ” ib O CO bj b/D .g ^ b co "d O co a 0 g a 0 5 r “ >-> b eg H 2 1 8 ENGINEERING. [Feb. 28, 1890. Bridges” (Engineering, vol. iii.) which went through three editions in this country, were republished at Philadelphia, and translated into German and Dutch, and published in the Trans- actions of the Austrian and Dutch engineers re- spectively. In 1871 Mr. Fowler and Mr. Baker made designs and estimates for a bridge across the Severn, com- prising two girder spans of 800 ft. each, and in 1873 Mr. Baker, at the request of the Corporation of Middlesbrough, designed the superstructure for a proposed ferry bridge across the Tees, which included a 650 ft. span on the same system (Engineering, vol. xvi., page 60). In 1876 nine competitive designs were submitted for the proposed New York and Long Island Bridge, comprising one span of 734 ft. and one of 618 ft., and of these three designs, two were on the aforesaid system (Figs. 13 and 14). The first was that of the Delaware Bridge Company, and the second of Colonel Flad, the very able engineer who, under Captain Eads, carried out the great St. Louis steel arch bridge. In the same year was built the first, and, so far as we know, the only railway bridge of the type under discussion (Fig. 15.) This is a bridge of 148 ft. span across the Warthe, near Posen. It might appear strange at first that the application to railway purposes of so well-known a system should have been deferred until 1876, but the explanation is that there are thousands of bridges in existence on the continuous girder, or in other words cantilever and central girder principle, but engineers as a rule have elected not to sever the bridge at the point of contrary flexure, or to make the girders of varying depth. A glance at the annexed illustrations and descrip- tion will satisfy our readers that there is nothing novel or untried in the principle of the structure designed for the F orth crossing. Thereasons dictat- ing the design in the case of the Forth Bridge are those which probably influenced the Red Indians in making the structure illustrated by Fig. 8 — economy of material and facility of erection. It must be conceded, however, that except as regards prin- ciple the design is essentially novel, but the novelties are dictated by the unexampled size of the structure, and are due simply to the perfect adaptation of the principle of the com- tinuous girder and the general laws regarding the strength of materials to the special conditions of the case. Thus it will be observed that the structure is a continuous girder of varying depth on plan as well as elevation, the central girder portion being of the ordinary width required for a double line of rails, and the cantilevers spreading out to an extreme width of 120 ft. at the piers. By this means the stresses 011 the horizontal bracing from wind pressure are much reduced, and lightness and compactness are attained. To further the same ends the whole of the vertical members are made of two struts inclined towards each other from base to summit and braced together. To reduce the extreme height of the structure, and bring the centre of gravity as low down as possible, the bottom members of the continuous girder are curved, springing from solid masonry piers at a height of 18 ft. only above high water, whereas in the design for the suspension bridge the main chains, carrying of course all the weight, were supported at a height of 550 ft. above the same point ! The main compression members are steel tubes ranging up to 12 ft. in dia- meter, the tubular form being adopted for two reasons, firstly, because experiments have shown that inch for inch the tubular form is stronger than any other, and, secondly, because the amount of stiffening and secondary bracing is thereby reduced to the lowest percentage. It might lie thought that columns 350 ft. in length were an untried novelty, but this is not so, as we have the precedent of the Saltash Bridge oval tubes 16 ft. 0 in. by 12 ft. 3 in. in diameter and 460 ft. in length, the strain upon which under the test load was higher per square inch than will be that on the steel columns of the Forth Bridge. The central girder portion is simply an ordinary double-line railway bridge of 350 ft. span with girders of a type intermediate between the girder of parallel depth and the bowstring. This is an economical type, and many Continental bridges have been so constructed. When lecturing some years ago, Mr. Baker, with a view of presenting in a form easily understood and popularly remembered, a simple diagram of the manner in which the principal stresses of a canti- lever bridge are distributed, devised the following arrangement of a human cantilever, or a living model of the Forth Bridge. (See Fig. 15a.) Two men sitting on chairs extend their arms, and support the same by grasping sticks which are butted against the chairs. There are thus two complete piers, as represented in the outline draw- ing above their heads. The central girder is repre- sented by a stick suspended or slung from the two inner hands of the men, while the anchorage pro- vided by the counterpoise in the cantilever end piers is represented here by a pile of bricks at each end. When a load is put on the central girder by a person sitting on it, the men’s arms and the anchorage ropes come into tension, and the men’s bodies from the shoulders downwards and the sticks come into compression. The chairs are representative of the circular granite piers. Imagine 3. That no untried material be used in its construc- tion, or in other words that no steel be employed which would not comply with the requirements of the Admiralty, Lloyd’s, and the Underwriters’ Registry, as determined by the experience ga ned in the use of many thousands of tons of steel plates, bars, and angles for shipbuilding purposes. 4. That the maximum economy be attained consistent with the fulfilment of the preceding con- ditions. We think it will be apparent to most engineers and bridge builders that the original sus- pension-bridge design complied with none of these conditions, whilst the girder design complies with all. Of the present design it may be truly said that all anticipations have been most brilliantly realised, and its merits can now, in the light of practical ex- perience, and of actual facts, be more easily pointed Fig. 10. Fig. 14. Fig. 9. TYPES OF CANTILEVER BRIDGES. the chairs one-third of a mile apart and the men’s heads as high as the cross of St. Paul’s, their arms represented by huge lattice steel girders and the sticks by tubes 12 ft. in diameter at the base, and a very good notion of the structure is obtained. The chief desiderata in the Forth Bridge, which is the largest railway bridge ever yet built, were clearly as follow: 1. The maximum attainable amount of rigidity, both vertically under the rolling load and laterally under wind pressure, sothatthe work when completed may by its freedom from vibration gain the confi- dence of the public, and enjoy the reputation of being not only the biggest and strongest, but also the stiffest bridge in the world. 2. Facility and security of erection, so that at any stage of erection the incomplete structure may be as secure against a hurricane as the finished bridge. out. In the first instance the distribution of weight not only offers the advantage of having the greatest proportion, nearly one-fourth of it, immediately over the main supports, where it is most easily erected, but it offers in those places where the wind pressure would act with the greatest amount of leverage, the least amount of surface to act upon. Thus, while in the central tower of the Inchgarvie pier, the most exposed to storms, the weight per foot run is 23 tons, and in the first bay of canti- levers 21 tons, in the central girders of 350 ft, length it is only a little over 2 tons per foot. In a similar manner the structure decreases rapidly in height and breadth of girders, as it extends from the massive central towers towards the extremities of the cantilevers. Again, for purposes of erection every portion of the structure, as put in position, offered itself as a staging for carrying operations further Feb. 28, 1S90.] ENGINEERING. ahead, or afforded every means of suspending tempo- rary staging from it. The greater portion of the work as erected could be securely fixed at once and rivetted up, and this close up to places where new parts were in course of erection. Great rigidity was thereby insured, and less temporary work required than in any other mode of construction, while it gave confidence to the workmen engaged, and offered every facility in providing for their safety, and for that of the structure itself. Great stability is obtained by straddling the sides of the structure, as viewed in cross-section — that is, making it considerably wider at' the base than at the top. In the central towers, the width at the base is somewhat more than one-third of the height, and a uniform batter is maintained throughout the structure. This feature conveys a sense of great security against the action of violent gales tend- ing to overturn the bridge. Finally, the arrange- ment of cantilevers and central girders admits of the simplest and most effective form of expansion- joint, and this problem is solved here in the happiest manner, as will appear from the detailed descrip- tion given later on. On December 21, 1882, the contract for the con- struction of the Forth Bridge was let to the firm of Tancred, Arrol and Co. Both the contract sum and the time specified, have been exceeded, for reasons which will be fully apparent to the reader who follows attentively the development of this work, and who gives intelligent consideration to the conditions under which it had to be carried out. Site of Bridge and Profile on Centre Line. Surrounding Countrv. The site which was finally fixed upon as the most suitable in all respects for carrying the bridg across, is in its natural features singularly wel^ adapted for that purpose. The general level of the country on both sides of the Firth lies at about the height at which it was required to carry the rails in order to afford sufficient headroom for the largest vessels in the Navy or merchant service. Should the project of making a ship canal between the F orth and Clyde — lately brought to the notice of the public — ever be carried into execution, and should the Forth thus become an international highway, as well as one of the finest natural harbours of refuge in the world, the largest vessel yet built would have to do no more than strike its topmasts should it happen to pass at the hour of high water of an extra high spring tide. The river bottom, in all places where the foun- dations of piers had to be laid, consists of either the hard whinstone rock or of hard boulder clay, both of great soundness and solidity. At no point where foundations had to be placed is there a greater depth of water than that well within the capabilities of sinking caissons by pneumatic pro- cess. The only contraction in nearly 50 miles of river is to be found here, and it reduces the width, elsewhere never less than fully two miles to one mile and about 150 yards. (See Fig. 10.) On the North or Fife shore, a rocky promontory, somewhat triangular in shape, projects southwards for fully a mile and a quarter into the river, and affords not only sound building material in its bedrock, but also sheltered corners for discharging vessels and anchorages for a small fleet of barges and launches connected with the works. From the apex of this promontory, nearly due south, the small island of Inchgarvie lies distant exactly one-third of a mile, and between the two runs the Main or North Channel with a depth of over 200 ft. This is the channel almost exclusively used by shipping, because it is safer and easier to navigate than the South Channel, and also because it is the shorter road of the two. Inchgarvie is a peak of basaltic trap-rock or whin- stone, and lies to the east side of the centre line of the bridge. It rises abruptly from the bed of the Firth except at its western extremity, where it widens into a broad toe with a tolerably regular slope to S.W. of about 1 in 7. On the south side of Inchgarvie lies the South Channel, which is of about the same depth and width as the North .Channel. Its southern edge, however, lies still about 30 ft. under water, and from it to the South or Queensferry shore there is a distance of 2000 ft. , one-fourth of which becomes uncovered at low water. In the South Channel the whinstone rock dis- appears about the centre, being from that point forward overlaid by a bed of very hard boulder clay of great thickness, this being in turn overlaid by about 40 ft. of a softer clay, gravel, silt, and soft mud. The ground rises from the edge of the deep water channel towards the shore with a gentle slope, the clay disappearing about half-way up, and giving place to ledges of freestone rock. It will thus be seen that the natural configuration of the ground on the centre line of the bridge, offers points for three main supports, of which the two outer ones are about equidistant from the central one, thus indicating two large spans of equal length, while the remaining spaces to be traversed on both shores, offer every facility for the construction of satisfactory foundations. As a matter of fact there has been no single instance of the ground on which the foundations were placed being uncertain or in any way doubtful, and no anxiety need be felt in regard to this part of the Forth Bridge. Indications of the nature of the ground on the centre line of bridge are given in Fig. 2 on Plate III. A general view across the river is shown in Plate Y. , from a photograph taken on September 11, 1883. The latter view shows the Hawes Inn and garden in immediate foreground, also the Hawes Pier, the Queensferry jetty, with the half tide cofferdam of No. 6 pier, and the commencement of the large cofferdam for the South cantilever end pier. It also shows the commencement of staging on Inch- garvie, and the same on Fife, with the new coast- guard houses on the first elevation to the right. The country immediately surrounding the site upon which the bridge now stands is strikingly beautiful. Whatever opinion may be held in regard to the lines of the bridge itself, it must be conceded that this bridge or any other bridge must be a discordant feature in a pastoral landscape. Standing on Mons Hill in Dalmeny Park, and looking down over its thickly wooded slopes into the broad exjianse of the Forth, with the island of Inchgarvie and its old castle breasting the swift current and cutting it into two arms, which below it, unite again in a whirl- pool glittering in all the colours of the rainbow, the whole backed by the Fifeshire Hills, the Ochills, and the great peaks in Dumbarton, Stirling, and Perthshire, is a view hard to be excelled in any part of the world. Hardly less fine and perhaps more grand still is the view down the estuary into the limitless ocean, from the grounds round Hopetoun House. In the last case the horizon falls in with the line of the rails of the internal viaduct, and thus shuts out all view most completely, while the lines of the bridge itself in geometrical repetition — with severe regularity — of triangles and squares, cannot be made to harmonise in the least degree with the soft and undulating lines of the adjoining landscape. Thus the best view of the landscape is from the bridge, because the disturbing element is left out, while by far the best view of the bridge is obtained from the river, whether above or below, at a distance of a mile or so, the structure rearing itself to a great height, and being backed only by the sky. Thus viewed, its simple lines, its well-proportioned parts, its impressive air of strength and solidity and yet of lightness and grace, never fail to strike the mind of the beholder. Four-square to the wind and immovable it stands ! The view from the. summit of the central tower on a clear day is magnificent. The broad river itself, with craft of all sorts and sizes, hr steam or under sail, running before the wind, cutting, across the current on the tack, or lazily drifting with the tide, is always a most impressive spectacle upon which one can gaze for hours with an admiring and untiring eye. And such it is, whether viewed in the glory of sunrise or sunset, in broad daylight with tlie cloud shadows flying over the surface, and a thousand ripples reflecting the sun’s rays in every conceivable shade of colour, or in the soft haze of a moonlight night. The sunsets in summer arc always magnificent, whether due to Krakatoan volcanic dust or to the vapours of the distant Atlantic, but there have also been many sunrises in early autumn when a hungry man could forget the hour of breakfast, and one could not find the heart to chide the worker who would lay down his tools to gaze into the bewildering masses of colour sur- rounding the rising light of day. An unbounded view more than 50 miles up and down river! Far away to east the May Island, often so clearly defined, though 35 miles distant, that the sun- lit cliffs are clearly visible, the Bass Rock and North Berwick Law, and the coast lino of Hadding- tonshire with the Lammermuir range fading into the sky, nearer Inchkeith with the white walls of the coastguard station and the lighthouse, Inch- j mickry and Cramond Island, the long jetties of 2 l 9 Leith Harbour and the shorter of Grr.nton and Newhaven, the roads full of shipping, the masses of houses in the marine suburbs of Edinburgh, Arthur’s Seat and Corstophine Tower just peeping over Mons Hill and the woods of Dalmeny Park. To the south, the fertile districts of the Lothians gradually rising to the imposing range of the Pent- land Hills, and to south-west Dundas Hill and Castle, Hopetoun House, and the old palace and church of Linlithgow, the harbours of Bo’ness and Grangemouth and the Campsie Hills closing in the upper Firth, still many miles wide with beautifully wooded shores, and many towns and villages upon its banks. Nearly GO miles to the west, as the crow flies, stands the massive cone of Ben Lomond, and behind it a formidable array of hills and moun- tains, clothed in the summer-time in the tenderest shades of purple and blue, in the winter showing forth boldly in a coat of purest snow. In the north- west appear the Ochills, in the north and north-east the Fife Lomonds and the beautiful coast of Fife running down into the horizon, where, glancing over the old priory on Inchcolm, the eye catches the May Island again. At night too a sight is presented not easily for- gotten ; the flashing lights of the May and of Inch- keith, and many others stationary, such as the harbour lights of Granton, Leith, Newhaven, and Burntisland combine to form a beautiful picture. At times of continued east wind, when large and small craft run for shelter in the Firth, it is not unusual to see from 150 to 200 vessels anchored in the roads, and the long straggling lines of their masthead lights give the appearance of abusy town of many streets having suddenly risen from the waters. On Jubilee night (21st June, 1887), although the atmosphere was somewhat thick, G8 bonfires could be counted at one time on the surrounding hills and isolated points, while the great masses of the central towers of the bridge lighted up by hundreds of electric arc lights — Lucigen and other lamps — at various heights where work was carried on, formed, with their long-drawn reflections in the waters of the Firth, three pillars of fire, and afforded a truly wonderful and unique spectacle. Tides, Wind, Wind Pressures, and Gauges. Climate Generally. The tidal rise at Queensferry, that is, the dif- ference between high water and low water during ordinary spring tides, is 18 ft.., rising occasionally to 21 ft. and even 22 ft. Owing to the contraction in the river, already spoken of, the velocity of the tide flow is considerable, more especially so in the North Channel. The strong currents running to each side of Inchgarvie have given a good deal of trouble, both during the erection of the extensive iron girder staging between the four main supports, and between them and the rock, and during the founding of the piers. Still more was this diffi- culty felt during the erection of the Inchgarvie north cantilever, when it was necessary to lift all material out of steam barges up to the structure direct, and when the combined influences of tide flow, set of current and wind, made it next to im- possible to keep the barges in place for a sufficient time to allow the lifting tackle to be attached even with a most skilful and experienced skipper at the helm. The only other drawback due to tidal action, was due also to the want of proper pier accommodation upon all three points. Until the timber stages and jetties were built, none of the landing places could be approached at low water except by small boats, and there was consequently a grievous waste of time from that cause in the early days. The prevailing winds are from the S.W. and the highest pressures recorded upon the wind gauges have invariably proceeded from that quarter ; next in point of frequency occurs an E.N.E. wind, which brings up heavy seas from the German Ocean, and which is as unpleasant to the senses and as trying to the temper as the proverbial east wind in London. From the N.W. come occasional blasts which have the effect of completely clearing the atmosphere, so that the most distant mountains show with considerable distinctness their every form and detail. S.E. winds bring rain and dirty weather invariably, and are fortunately not of frequent occurrence. It is a curious fact that while in spring and summer the east wind brings with it an icy chill, while the west winds are warm and genial, the latter in the winter time bring whatever frosty weather comes to pass, which is immediately broken up into thaw by a change in the wind to east. 220 ENGINEERING. [Feb. 28 , 1890 . East winds are prevalent generally in April, May, and June, but sometimes continue right through the summer, but for the remainder of the year, often for many weeks without change, the south-west wind keeps in possession. The variations in temperature are not excessive, and may be said to range between 20 deg. Fahr. and 85 deg. Fahr. minimum and maximum in the shade , respectively. Far greater than storms to the sailing craft pass- drift about helplessly in the powerful currents. At such times the barges and launches belonging to the works were on the look-out to run to the assistance of any shipping becalmed and tow them into mid- channel. To ward off all craft from the iron staging Fig. 5a. Living model illustrating principle of the forth bridge. On three or four days during the year gales blow with such violence as to stop even large paddle boats from attempting the passage. On many other days the smaller barges and launches have to keep within shelter. During such times all outside work was necessarily stopped owing to the impos- sibility of handling material by the derrick cranes, or of getting about on the exposed stagings. From twenty-two to twenty-three full working days in the month must be considered very satisfactory in this climate ; on many days only an hour or two need have been lost but for heavy rains in the early hours, which drenched the men and sent them to their homes. When such happened no power of persuasion was great enough to bring them back to work again, even if the weather turned fine and con- tinued so for the rest of the day — a curious fact not easy of explanation. Of snow there was but little during the seven winters, and but few days were lost through its covering the ground, but the frost caused much stoppage in a work where hydraulic appliances were so largely used, and where, owing to the enormous extent to which pipe leads had to be carried, it was impossible to effectively protect them all. It was thus the practice to break a number of joints and allow all pipes to drain dry after work stopped at night. Some of these joints were on deck, others on the very top of the structure, and a fire which occurred one night, F ebruary 13, 1889, on Inchgarvie spread to an alarming extent, and might have had most serious consequences to the lower portions of the steelwork as well as to the granite piers before the joints could be closed and the pumps made effective. The danger was all the greater that a furious gale was blowing from the south-west, which made it a matter of some danger to get to the island at all, or when there to ascend to tire top of the superstructure to find the broken joints. Fig. 1C. Map of the firth of forth. ing the bridge is the danger from sudden calms , on Inchgarvie, where they would certainly have come which frequently occur during spring tides when a to grief, but where they also might have done con- strong ebb is running, and which cause them to 1 siderable injury to the structure in the early day? Feb. 28 , 1890.] ENGINEERING. 22 t of erection, three timber booms, each boom consist- ing of three heavy Oregon pine legs, were moored to the west of Inchgarvie. The logs were octagon section, from 2 ft. to 2 ft. 6 in. across, and about 100 ft. long, and were strongly bound together by three heavy iron belts to each boom. Mooring blocks weighing nearly 40 tons each were laid down in the bed of the Firth, some 120 yards west to the booms. On the side of the island heavy iron stakes were fixed in the rock, and to these or else to some of the iron columns, lj in. cable chains were attached. The other ends of these chains were shackled to the pointed ends of large floating buoys, and the same shackles received similar chains comingfrom the large mooring blocks. On the tops of the buoys were large rings, and to these were attached the chain bridles from the ends of the floating booms, orratherfrom the as to register for any direction of wind. There was no provision made for registering intermediate pressures, nor particulars as to direction of wind or times of occurrence, except in so far as the records were taken generally at 9 a.m. every day. The principal gauge (Fig. 17) is a large board — 20 ft. long by 15 ft. high, or 300 square feet area — set vertically with its faces east and west. The weight of this board is carried by two rods suspended from a framework surrounding the board, and so arranged as to offer as little resistance as possible to the passage of the wind, in order not to create eddies near the edge of the board. In the hori- zontal central axis of the board there are fixed two pins, which fit into the lower eyes of the suspen- sion-rods, the object being to balance the board as nearly as possible. Each of the four corners of the order to ascertain, to some extent, how far great gusts of wind are quite local in their action, and exert great pressure only upon a very limited area, two circular spaces — one in the exact centre, and one in the right-hand top corner — about 18 in. in diameter, were cut out of the board, and circular plates inserted which could register independently the force of the wind upon them. By the side of this large square board, at a dis- tance of about 8 ft. , another gauge — a circular plate of I),- square feet area, facing east and west — was fixed up with separate registration. This was in- tended as a check upon the records given by the large board. Another gauge of the same dimensions as the last, but with the disc attached to the short arm of a double vane, so that it should face the wind from iron bolts near the ends. Sufficient slack was allowed in all chains for rise and fall of tide. These timber booms have been the means of saving many small boats and sailing schooners from certain shipwreck. With the calm weather in winter and early spring the sea fogs or eastern haars occu 1 ’ with tolerable frequency, and have caused much anxiety on account of the necessity of having to carry large numbers of workmen — many hundreds every morning and night — from either shore to their destinations. These fogs come up the Firth like a solid wall of dazzlingly white cloud, sometimes leaving the tops of the towers standing out clearly in the sunshine, at other times hanging some 50 ft. to 100 ft. up in the air, and leaving the lower por- tions quite clear. The effect is well shown in the illustration from a photograph given on Plate XII 1. Wind Pressure and Wind Gauges. The wind pressure to be provided for in the calcu- lations for bridges in exposed positions is 50 lb. per square foot, according to the Board of Trade regula- tions, and this twice over the whole area of the girder surface exposed, the resistance to such pressure to be by deadweight in the structure alone. The most violent gales which have occurred during the construction of the Forth Bridge are given with the pressures recorded on the wind gauges in the annexed Table, No. I. It is worthy of observation that only one gale from easterly direction is recorded — January 5, 1888 — but there have been a number of gales from that quarter registering between 15 lb. and 16 lb. and up to 20 lb. per square foot, and, of course, the same from other directions. The pressure gauges which were put up in the summer of 1882 on the top of the old castle on Inchgarvie, and from which daily records have been taken throughout, were of very simple construction. As the object was to ascertain only the maximum pressures which the structure would eventually have to resist, the maxima only were taken. The most unfavourable direction from which the wind pressure can strike the bridge is at right angles to the longitudinal axis, or nearly due east and west, and two out of the three gauges were fixed to face these directions, while a third was so arranged TABLE No. I,— Records of Wind Gauges on Inchgarvie during Violent Gales. Pressure in Pounds per Square Foot. Year. Month and Day. Right- Direction Eevolv- Small Large In Centre hand of Wind. ing Fixed Fixed of Large Top of Gauge. Gauge. Gauge. Gauge. Large Gauge. 1883 December 11 33 39 22 SAVA 1884 January 26 65 41 35 — — SAVA 1884 October 27 29 23 18 — — SAV. 1884 ,, 28 26 29 19 — — SAV. 1885 March 20 30 25 17 — — W. 1885 December 4 25 27 19 — w. 1886 March 31 . . . 26 31 19 — — SAV. 1887 F ebruary 4 26 41 15 — — SAV. 1888 January 5 . . . 27 16 7 — — S.E. 1888 November 17 35 41 27 — W. 1889 2 27 34 12 — — SAV. 1890 January 19 27 28 16 — — SAV. 1890 21 26 38 15 — — W. 1890 „ 25 27 24 18 23 h 22 SAV. by W. * These data are unreliable, owing to faulty registration by the indicator needle, as will presently be explained They were altered after this date. The barometer fell to 27.5 in. on that occasion — over $ in. within an hour. board is held between two spiral springs, all care- fully and evenly adjusted so that any pressure exerted on either face will push it evenly in the opposite direction ; but on such pressure being I removed, the compressed springs will force the j board back to its normal position. To the four corners four u'ires are attached, uniting in pyra- 1 midal formation in one point, whence a single wire passes over a pulley to the registering apparatus below. This in the original arrangement consisted of two levers at right angles to one another, the shorter one — about one-third of the other— being acted on by the wire from the windboard, the longer one witli an index pointer registering the amount upon prepared paper slips. The indication by the pointer was thus about three times the amount of travel of the wire up and down. In whatever direction it might come, was set up (see Fig. 18). This also had a separate registering appa- ratus arranged in the same manner as the two first described. Fig. 17 gives tw r o views of the large wind-board with the tw r o independent gauges at A and B. Fig. 18 shows the revolving wind gauge, consisting of a circular disc hung in four bent springs, and rods which centre in the point M. Here a horizontal crossbar connects the two opposite springs, and to this bar, immediately opposite the centre of the hollow vertical spindle P, a small chain is attached, which passes through a slot in P over the pulley N, and right down the centre to the registering appa- ratus below. The double vane is fixed upon P, which revolves in the socket column R. The small fixed gauge is of the same construction and area, O') ) the only difference being that the vane is absent, and P is a fixture in R and cannot turn. The circular disc of course faces west. It is needless to say that these gauges were not expected to give very accurate records of the wind pressures which occurred since they were put up, but they give a sufficiently approximate idea of what the structure will hereafter have to encounter in the way of wind. Upon one occasion the small fixed board appeared to register 65 lb. to the square foot, a registration which caused no little alarm and anxiety. Mr. Baker, however, declined to accept the figures re- corded, and on investigation found that, with the lever multiplication-pointer, it was not difficult to obtain high figures, owing to the lever acquiring momentum from a suddenly applied force such as a strong gust of wind would produce, thereby over- shooting the mark. Thus a blow of about 20 lb. applied smartly to the gauge would register 65 lb., and would probably have registered more but that the pointer could go no further. This occurred in January, 1884, and since then the recording appa- ratus has been altered, the horizontal lever being done away with, and a vertical bar — suspended directly from the wire of the gauge — being substi- tuted. Since then the highest pressures recorded have only been 35 lb., 41 lb., and 27 lb. respectively. A gale on March 31, 1886, gave the following results : — Upon the small fixed gauge 31 lb. to the sq. ft. ,, revolving ,, 26 ,, ,, In the centre of the large board 281 ,, ,, ,. upper corner ,, 22 ,, ,, All over the large board It) ,, ,, These figures seem to indicate that the higher wind pressures come more in gusts and sudden squalls than in a steady and even pressure extend- ing over a large area. After the central towers had been carried up to the full height, two additional revolving gauges — one at the north-east and one at the south-west corner of each tower — were put up and records taken and compared with those given by the other gauges. The records confirm most distinctly the results of the smaller gauges inserted upon the large board — for the pressures recorded vary as much as 10 lb. and 12 lb. between the different piers — sometimes the one, sometimes the other, showing the higher registration. Experiments on Wind Stresses. The scanty information existing on the very important subject of the action of wind pressure on the surfaces of structures, whether flat or curved, induced Mr. Baker to make a series of experiments, upon the results of which it would be possible to form some definite conclusions. These experiments are so interesting, and the appli- ances by which they were obtained were so inge- nious, that no apology is needed for their repeti- tion here. Realising the difficulty of working with models in actual wind, which is never, so to speak, of the same intensity or direction for two consecutive moments, and labouring under the disadvantage of not having an instrument which would reliably indicate the actual pressure at any time, Mr. Baker simply reversed the order of things by making the wind stationary and the apparatus movable. The latter then consisted of a light wooden rod, suspended in the middle, so as to balance correctly, by a string from the ceiling. At one end of the rod was attached a cardboard model of the surface the resistance of which was to lie tested, be it a portion of a round tube, a flat- tened strut, a piece of top member, or of the internal viaduct, or even of a whole cantilever. On the opposite end of the rod was placed a sheet of cardboard facing the same way as the model, so arranged that by means of another and adjust- able sheet, which could slide in and out of the first, the surface at that end could be increased or decreased at the will of the operator. The mode of working this contrivance is for a person to pull it from its perpendicular position towards himself, and then gently release it, being careful to allow both ends to go together. If this is properly done, it is evident that the rod will in swinging retain a position parallel to its original position, supposing that the model at one end and the cardboard frame at the other end are balanced as to weight, and that the two surfaces exposed to the air pressure coming against it in swinging are exactly alike. Should one area be greater than the ENGINEERING. other, the model or the cardboard sheet, whichever it may be, will be lagging behind, and twist the string. By now increasing or diminishing the area of the cardboard sheet and repeating the experi- ment over and over again, a point will be reached when the whole mass will swing without twisting being produced. The area of the cardboard will then represent the exact area of the model which is affected by wind pressure. The experiments carried on in various ways by different people and at different times are generally in agreement with each other, and not very dif- ferent from those arrived at by scientists with most complicated apparatus, and by laborious and pains- taking processes. The points on which reliable information was more particularly wanted were in respect of surfaces more or less sheltered by those immediately in front of them. In the case of any box lattice girder, for instance, assuming that the wind was blowing fully square at it, it might also be assumed that the side nearest the wind would cover the side of the girder lying behind; but if the wind blows at an angle to the girder, it is certain that the second surface receives its proportion of full pres- sure of the wind ; and in cases where two lattice box girders are close together — as, for instance, in the top member — all four surfaces will receive a pro- portionate amount of wind pressure. It may easily be understood that the distance from each other of these surfaces has a great deal to do with the amount of wind stress they receive, and it was with a view of obtaining some useful data with regard to this question that Mr. Baker’s experiments were carried out. Information exists about flat surfaces and curved surfaces, and also about cubes — that is, two or more sides of any rectangular box or girder upon which the wind acts in a more or less diagonal direction. In all these Mr. Baker’s experiments agreed with those of other observers, and obtained with different apparatus ; but in the case of shel- tered surfaces the results were somewhat different. On the whole, however, Mr. Baker satisfied him- self that in no case was the area affected by the wind in any girder which had two or more surfaces exposed more than 1.8 times the area of the sur- face directly fronting the wind. As the calcula- tions have been made for twice this area, the stresses which the structure will receive from this cause will be in all cases less than those provided for. Mr. Baker also tested models of girders built of metal, both in air and in water, and although some slight differences with the former result were found, yet on the whole they fully confirmed the general conclusions arrived at. The observations now made on the completed structure will no doubt help to throw further light on this subject of great importance to engineers, since in large structures the wind stresses are of considerably greater moment than the train loads, and should therefore, for economical considerations, be reduced to the narrowest limits compatible with absolute safety. General Description of the Structure. (See Plate III., Figs. 1 to 29). From the general view of the bridge in profile it will be seen that it consists of two approach viaducts and of the cantilever bridge proper. The viaducts only dift’er in extent ; the height above water and the lengths of the spans being the same. It will also be seen that a similar viaduct which forms the railroad or permanent way is carried through the cantilevers and central towers at one uniform level. Commencing at the south end there are four granite masonry arches which terminate in the abutment for the South Approach Viaduct. Here the girder-spans commence — 10 in number — the end of the last being supported in the south cantilever end pier. On the north shore there are three similar masonry arches, terminating in an abutment, and five girder-spans to the north cantilever end pier. The bridge proper consists of three double cantilevers and two central connecting girders. Each double cantilever consists of a central tower supported on four circular masonry piers — a canti- lever projecting from each side of it. The two outside piers — the Fife and Queensferry — have, in addition to the four supports of their central towers, a further support, inasmuch as their outer cantilevers rest in the cantilever end piers. No [Feb. 28, 1890. such additional support was available in the case of the Inchgarvie pier, and the length of the base has here been nearly doubled. The reasons for this are given further on. The length of the cantilever bridge is 5,330 ft., consisting of the central tower on Inchgarvie, 260 ft. ; the Fife and Queensferry central towers, 145 ft. each ; the two central connecting girders, 350 ft. each; and six cantilevers of 680 ft. each. The cantilever end piers are apart 5,349 ft. 6 in. from centre to centre. The South Approach Viaduct is 1,978 ft. long from centre of cantilever end pier to end of arches, consisting of ten spans of 168 feet each ; four arches of 66 ft. each centre to centre, and 34 ft. made up by abutments. The North Approach Viaduct is 968 ft. 31r in. long to end of arches, consisting of five spans of 168 ft. long; three arches of 37 ft., 31 ft., and 46 ft. centre to centre respectively, and 14 ft. 3^ in. made up by abutments. The total length of the structure is therefore 8,295 ft. 9) A in. The two main spans are 1,710 ft. from centre to centre of vertical columns, made up of two cantilevers of 680 ft. each, and one central girder 350 ft. The waterway to be crossed is about 5,700 ft., extending from the south circular piers on Fife to Viaduct Pier No. 3 at Queensferry. The rail level has been fixed at 157 ft. above high water, which leaves for a total length of 500 ft. in the centre of each channel a clear headway of 151 ft., no train load being on the bridge. The ordinary load of two trains is not expected to diminish this head- way by more than about 3| in. The Fife and Queensferry Piers are alike and identical in every respect, and only reversed with regard to their outer cantilevers. All six canti- levers are the same in length — namely, 680 ft. from centre of vertical columns to centre of endpost — and are also of the same height and width, namely, 330 ft. high at the central towers, by 120 ft. wide at bottom, and 33 ft. wide at top, and 34 ft. high at the endposts, with a width of 32 ft. at bottom and 22 ft. at top. The only difference in the can- tilevers lies in the arrangements of the endposts, and further in the fact that the two outside or fixed cantilevers of Fife and Queensferry are somewhat heavier in construction than the others. E ich can- tilever consists of a bottom member, or compres- sion member, and a top member, or tension member — these being braced together vertically by six pairs of cross-bracings on each side, and being closed at one end by the vertical columns, at the other end by endposts. The space occupied by each pair of side-bracings is termed a bay, of which there are six in each cantilever. The bottom mem- bers are connected together by twelve sets of hori- zontal diagonal bracings intersecting in centre line, and further by the trestles and cross-girders, which carry the internal viaduct. The side bracings connecting top and bottom members consist each of a strut or compression member and a tie or tension member intersecting one another, and being connected at the intersections by strong gusset-plates and other stiffening. Each pair of opposite struts is connected by diagonal wind- bracings both above and below the internal viaduct, and by a cross-girder at top between the top mem- bers. F rom the intersection of struts and ties in the sides of the cantilevers, lattice girders, called vertical ties, are carried downwards and attached to the bottom members, relieving the latter of deflec- tion between the junctions. Cross-sections of the cantilevers at each pair of struts and each pair of vertical ties are given in Plate III., Figs. 11 to 29. Each central tower is formed of four columns, each column resting on a circular granite pier. Transversely all these piers are 120 ft. from centre to centre, or 60 ft. on each side of the centre line of the bridge. Longitudinally these piers are 155 ft. apart from centre to centre in the Fife and Queensferry Piers, and 270 ft. in the Inchgarvie Pier. It follows that the central tower on Inch- garvie is much heavier in construction and different in several features from the other two. All the circular granite piers are carried to a height of 18 ft. above high water, and the height between the centres of bottom members and top members is 330 ft.., measured vertically, which gives an extreme height of the central towers above high water of 361 ft. The vertical columns — so called for distinction — are vertical only in one sense ; that is, when look- ing broadside on. In the other sense, looking along the centre line of the bridge, they have an inclination of about 1 in 7A, being apart, centre to Feb. 28, 1890.] ENGINEERING. centre, 120 ft. at bottom and 33 ft. at top. This batter of the vertical columns is maintained through- out the cantilever bridge. It had been intended to so arrange the sides of the cantilevers that the batter of 1 in in the central towers should gradually decrease until a vertical position was attained in the endposts and the central girders ; but this plan would have led to considerable com- plications in the junctions both in top and bottom members, and in the intersection of struts and ties, and would have produced a twisted toj> member. There can be no doubt that the arrangement of a uniform batter throughout the structure adds materially to its appearance, by giving it harmo- nious and simple lines, and heightens the impres- sion of stability and resistance to lateral wind pressure. The investigations and experiments made by Mr. Baker, and extending over several years, have led to the decision that all members under compres- sive stress should be of tubular form — circular by preference where admissible — this form being the strongest, weight for weight. This rule is, for structural reasons, only departed from in the struts of Bay 6 of the cantilevers and in the struts and top member of the central girders. All members under tensile stress are open lattice girders. Thus the bottom members — the vertical columns and the struts in cantilevers are always under com- pression and are tubular in form, while the top members, the inclined ties in cantilevers and vertical ties are invariably in tension, and are of open lattice-girder form. The diagonal struts in the central towers again, although always in com- pression from dead load or wind pressure, receive an alternate tensile or compressive stress, and vice versa, according to the direction from which the live load or train load enters on the pier. In a similar way the diagonal wind bracings between bottom members, the vertical columns and inclined struts in cantilevers, are exposed to varying stresses according to the direction of the wind, and they are likewise affected to some degree by the position of the sun. In order to preserve balance so far as dead load is concerned, it became necessary to load the ends of the outer or fixed cantilevers to the extent of half the weight of a central girder. To this end the endposts of these cantilevers ate formed in a large box built of plates and filled with dead weight to the required extent. Thus far then the conditions would be alike for all six cantilevers in the state of rest, and in the absence of wind pressure and train load. Any introduction of the latter would at once disturb the balance, and, therefore, additional weight was placed in the ends of the fixed cantilevers large enough to counterbalance any possible train load which is likely to pass over the opposite end and leave a couple of hundred tons to the good. Under these circumstances the ends of the free cantilevers in the Fife and Queensferry Piers cannot deflect except in so far as deflection is due to the elasticity of the steel. On the other hand the fixed end will receive a downward pressure of, in the case of the maximum, the weight of the counterpoise, plus the maximum train load, and in the case of the mini- mum, the weight of the counterpoise minus the maximum train load, and of course any number of loads varying between the two. It will thus be seen how changeable are the conditions of load in the cantilevers, and the stresses upon the different members. I 11 the central or Inchgarvie Pier the conditions are different. There the weight of half a central girder is carried at each end, and so far as dead load is concerned the balance is absolute. But every ton of train load introduced from either end will upset this balance at once, and it was therefore essential to provide for every contingency. The worst con- dition that can be assumed would be for two trains to meet in the central girder at one end. The tendency would then be to form a fulcrum of the two nearest circular granite piers and lift the struc- ture off the two furthest piers. As it was not intended that the anchorage in these piers, that is the holding-down bolts, should ever be brought into play except under the most improbable conditions of hurricane pressure, it was necessary to make the base of the central towers so great that the con- tingency stated above could not possibly arise. It is for these reasons that the central tower of the Inchgarvie pier has so much longer a base than either the Fife or Queensferry. The four vertical columns are combined together and are braced in various ways. Longitudinally they are connected at bottom by the horizontal { portions of the bottom members, and at top by those of the top members, both of these being carried through in unbroken section. The four corners of the rectangle thus formed are connected by a pair of diagonal struts intersecting eacli other at the centre. In order to facilitate the intersection these struts — and for similar reasons the struts in the canti- levers — are flattened throughout on both sides, and at the points of intersection are considerably stiffened and almost doubled in the plates. At this point a horizontal bracing girder is carried across and attached to the vertical columns on either side. In the case of the central tower on Inchgarvie, owing to the greater distance between the piers, the top and bottom members cannot be carried for the whole distance without deflection, and a vertical tie is therefore brought down from the intersection of the diagonal struts and attached to the bottom member, while a vertical supporting column is carried up from the same point to take up the deflection in the top member. In the lateral sense at the base of the columns there are two horizontal bracing girders and one pair (in the case of Inchgarvie two pairs) of hori- zontal diagonal bracing girders of great strength and stiffness, thus forming with the horizontal bottom members a very rigid framework imme- diately over the circular masonry piers. A similar double set of cross-bracings — though of much lighter section — is placed at the level of the inter- section of the diagonal struts, thus bringing these points into direct connection with the four vertical columns half way up the towers. Between the vertical columns are placed four sets of vertical cross-bracings, the lowest of which also assist in carrying the internal viaduct at these points, and horizontal bracings at top between the top members. A similar bracing is placed between top members at the top of the central supporting columns and the vertical central ties on Inchgarvie above described. All these members combined together form a tower of immense strength and w r eight, well able to take ujj and resist the enormous stresses resulting from the combined influences of dead load, live load, and wind pressure upon the tower itself and upon the cantilevers projecting from it. All these stresses, however, must ultimately resolve them- selves in those portions immediately resting on the circular masonry piers, which are called the skew- backs or main junctions. These junctions are the gathering points of five tubular and five latticed girders, and as their construction will be described in detail further on, it is only necessary to mention here that they terminate at foot in a flat plate called the upper bedplate, which is so arranged that it rests on, and, in some cases, can slide or move on another bedplate, the lower bedplate, which is fixed to the masonry pier. The functions of these bedplates in resisting and yet partially yielding to the wind-pressure and in taking up the expansions and contractions in the central towers are of so important a nature that they have received a very large amount of care and thought on the part of the engineers. The diffi- culties were avoided in the original design of Messrs. Fowler and Baker, and were consequent upon the modifications introduced by the other consulting engineers. It had been the intention originally to make the skewbacks an absolute fixture upon the piers, after having given an initial compressive stress to the horizontal tubes between the piers, also to clothe these tubes inside and outside with some non-con- ducting material which would practically neutralise the effects of heat or cold upon them. On re- consideration, however, it was decided to only fix one skewback out of the four comprised in each pier, and to allow the other three to yield to a limited and well-defined degree to the influences of tem- perature, and to the lateral deflections produced in the cantilevers by wind pressure, and to some degree also by the heat of the sun. It suffices for the moment to say that, for various reasons, the south-east pier on Fife, the north-east pier on Inchgarvie, and the north-east pier on Queensferry, were chosen as the fixed points. The arrangements of the bedplates, and the reasons for these arrangements, will be stated further on in connection with the provisions made for expansion and contraction in the main spans, and for distor- tions produced by wind pressures. '■ It will be noticed that the bottom member in the 2 2^ j cantilevers is not arched or curved, but polygonal in form, each portion from junction to junction being o. straight line and passing into the next portion with a nick or kink. Apart from the fact that a piece of straight tube is stronger than a bent one, some consideration was given to the manufac- ture of the plates for these tubes. Had they been curved, nearly every plate on the circumference would have had to be shaped in a different die — a difficulty still more increased by the decreasing diameter of the tube from 12 ft. at the skewback to 65 ft. at the end of the fourth bay, after which the member becomes gradually rectangular in form. The top member, being always in tension, is straight from the top of the vertical columns to the top of the endpost which closes the cantilever. It is carried uninterruptedly through all the junc- tions with struts and ties, though its cross section decreases gradually towards the point of the canti- lever. The central connecting girder consists of a top compression member, polygonal in form, and a straight bottom or tension member, with eight sets of vertical cross-bracings to each side, consisting of struts and ties, the struts being, as in the canti- levers, provided with diagonal wind-1 tracings. The top members are also connected by sixteen sets of diagonal horizontal wind-bracings. From the points of intersection of struts and ties a vertical lattice tie is brought down to carry the bottom member midway between junctions. The bottom members are connected by solid plate girders going right across — these carrying the rail troughs; and they are further stiffened by diagonal T bracings and by the solid floor of buckle plates. The internal viaduct which carries the permanent way of a double line of rails and a footpath on each side, consists in the main of two lattice girders, set 16 ft. apart, centre to centre, and of varying depth, according to the length of span. Both top and bottom booms are trough-shaped, the top booms receiving the longitudinal sleeper and rails. A cross-bearing girder occurs about every 11 ft., and upon this are laid the two inner rail-troughs, leaving the 6 -ft. way between them. The main girders differ in their construction from those in the approach viaducts, in so far as they have vertical struts and diagonal ties. They are also continuous and without break from the end of one cantilever through the central tower to the end of the other cantilever. A footpath about 4 ft. 6 in. wide on the outside of each outer rail-trough is carried on brackets attached to gussets both to the top and bottom booms of the main girders. The footpaths are formed by buckle plates, and buckle plates are also fixed between the rail-troughs and in the 6 -ft. way, thus making up a very stiff' flooring. The bottom booms of the main girders are connected by horizontal cross-bracings. It may be as well to mention that the footpaths are to be used only by the railway officials. The trains are intended to be run over the bridge at full speed, and it would lie neither convenient nor safe to admit the general public. The girders of the internal viaduct are carried between the vertical columns (and in the case of the Inchgarvie pier between the central vertical ties) by a plate-girder reaching right across, and by vertical supports carried upwards from the intersection of the first pair of vertical wincl-bracings between columns. The same mode of supporting the viaduct is adopted at the centres of the first and second bays in cantilevers, while at the ends of the first, second, and third bays, as also at the centre of the third bay, trestles, supported by the bottom members, are arranged. At the centre of the fourth bay a cross-girder carries the viaduct girders, and after this, the bottom member closely approaching the line of the viaduct, similar cross girders are used with short vertical supports. In bays five and six the girders are absent, and the rail troughs, stiffer in section, are there carried by cross-girders and by the diagonal wind-bracings alternately. In the central connecting girders the rail troughs, as already mentioned, are carried by solid plate- girders about every 22 ft. To each side of the internal viaduct a wind fence 4 ft. 6 in. high, and of lattice construction, is carried from end to end of the bridge, and on the approach viaducts. The viaduct girders and rail troughs are rigidly fixed to the cantilevers, and form an essential part of the latter, adding considerably to the stiffness laterally of the bottom members, The only breaks 224 ENGINEERING. [Feb. 28, 1890. occur at the junctions of cantilevers with the central girders. _ The viaduct must therefore expand and contract and move in every way with the cantilevers, and these movements will be considered presently. It remains to mention the various influences to which the structure or portions of it are likely to be exposed. 1. Expansion and contraction by changes of temperature, acting in the direction of the longitu- dinal axis of the bridge, and to some extent also transversely upon the circular masonry piers. 2. Influence of the sun’s rays to one side or the other of the structure. 3. Wind pressure, acting at right angles or nearly so to the centre line of the bridge. Provisions for the first are made in the sliding as distinguished from the fixed bedplates, in the joints between the ends of cantilevers on Inchgarvie Pier, and in the cantilever end piers at Fife and Queensferry. Provisions for the second and third are made in the sliding bedplates of the two outer or fixed cantilevers, and in all the joints between ends of free cantilevers and central girders. All these movements are horizontal and are controlled and confined within specified limits. The arrangements to meet these will be described in detail further on. The vertical deflections due to dead load, live load, and wind pressure, whether acting singly or in combination, have already to some extent been described, and will be further considered later. Expansion joints are also provided in the ap- proach viaduct girders upon every second pier, two spans being made continuous, the intermediate fixed joints being, however, placed on sliding bed- plates identical with the movable ones. In the two large spans of the cantilever bridge, longitudinal movements are only possible at the Inchgarvie ends of the central girders, the Fife and Queensferry ends of the girders being fixed so far as this movement is concerned. These ends there- fore move with, and in the same direction as, the cantilevers upon which they are resting. It has already been stated that the south-east circular pier of Fife, the north-east on Inchgarvie, and the north-east on Queensferry, are the fixed points of the structure. The movements due to longitudinal expansion or contraction are controlled and limited by these fixed points, and extend from them as pivots to the various extremities of the cantilevers and central girders. The lengths affected are as follows. (See Fig. 19.) 1. The Fife central tower, 145 ft., plus outer or fixed cantilever, 680 ft., total, 825 ft. in length, the expansion of which must be provided for in the north cantilever end pier. 2. Fife south or free cantilever 680 ft., plus length of north central girder 350 ft., total 1030 ft., the expansion of which will go towards Inchgarvie, while the expansion of the Inchgarvie north canti- lever, 680 ft., will go towards Fife. The total amount of movement to be provided for at the Inchgarvie end of the north central girder where the two movements overlap, will be that due to the expansion of 1710 ft. of girders. 3. Inchgarvie central tower, 260 ft., plus Inch- garvie south cantilever, 680 ft.., total 940 ft., the expansion of which will go towards Queensferry, while the south central girder 350 ft., and the Queensferry north cantilever 680 ft., make up a total length of 1030 ft., the expansion of which will go towards Inchgarvie. The total movement at the Inchgarvie end of the south central girder where the two expansions overlap, is that due to a total length of 940+1030= 1970 ft. 4. The movement between the north piers on Queensferry and the south cantilever end pier is due to the same length as on Fife, namely 825 ft. So far as observations up to this time have gone it would appear that the expansion or contraction amounts to about T J 0 t.h of an inch for each degree of temperature for every 100 ft. of girder length. The changes in temperature have, however, been so slight, and so near mean temperature that the figures cannot probably be accepted as quite correct. Assuming for the moment their correctness, the movements would be, for 70 deg. of full range : 1. 3.61 in. 2. 7.6 in. 3. 8.62 in. 4. 3.61 in. These figures only give about 70 per cent, of the estimated amounts, and the provision made at the four points mentioned for longitudinal movement is more than double that given above. Commencement of Work. Soon after the contract was signed in December, 1882, a start was made with the preparatory and temporary work. Offices and stores as well as a workshop, hereafter known as No. 1 shed, had been erected by Mr. Arrol in connection with Sir Thomas Bouch’s suspension bridge, and these were taken possession of and considerably added to from time to time. To enable the contractors to make an early start with the permanent work, that is, the building of the masonry piers, it was necessary that the posi- tions of these should be fixed without delay. A possible, the correctness of the distances apart of the three principal stations on the centre line of the bridge, which had been obtained by calculation based upon the triangulation, a measurement of the north span of 1700 ft. from the centre of the north circular piers on Inchgarvie to the south circular piers on Fife was made in the summer of 1884. In a straight portion of the North British Rail- way a distance of 1700 ft. had been carefully measured and marked and transferred to high posts at the side of the cutting. Upon these posts notched knife-edges were placed at the two ex- tremities. A fine steel wire about ^ in. in thick- ness was laid along the span and drawn over the knife-edges with a certain amount of stress put upon it, previously agreed upon. Thus drawn up the wire left a certain amount of sag in the centre, base line about 4000 ft. in length was laid down along the high ground on the south shore, starting from a point in the centre line of the bridge, pass- ing along the North British Railway for some dis- tance and terminating opposite the east breakwater at Port Edgar. Along the breakwater a timber gangway was erected, and near the far end of it, at a distance of about 3000 ft. from the base line, an observatory was built. Three points on the centre line of the bridge, one on the Queensferry shore, one on Inchgarvie, and one on the Fife shore were marked down, and their distances stated by the Ordnance Survey of Great Britain. Various other stations, about twenty in number, were laid down as required, and by means of these a most careful triangulation was made and the centres of the three main piers finally fixed. Tu order to verify, if which was carefully measured by level and noted. Two narrow copper tags were then soldered on, to mark the end points. The wire was then coiled up and kept ready for use. The temperature also was noted. On the two shores immediately under the piers which marked the stations, places had been pre- pared for levels, by means of which the amount of sag in the wire could be fixed. On a calm, cloudy day, with the temperature about the same, the wire was taken across the north channel and laid down upon the prepared knife-edges on the piers, and with the same amount of stress put upon it, and with the same amount of sag allowed, the two copper tags soldered on should have coincided with the notches in the knife-edges, provided the dis- tance was correct. Feb 28. 1890 ] It was, however, found about 15 in. short, and, although carefully tried several times over, the result did not vary. Since the span has been completed the measure- ments made along the girders have reduced the error to about 9 in., which, to nearly the same amount, exists in the south span also, both being shorter than intended. The work of triangulation was carried out by Mr. R. E. Middleton, M.I.C.E., and a full record of his labours is given in a pamphlet published by E. and F. N. Spon, London, about two years ago. For several reasons the positions of the four circular granite piers on Fife were first fixed, and soon the work there was in full swing. The greater portion of the old coastguard station, which was situated on the site now occupied by the north-east pier, had to be removed, and an entirely new station built on the rock further to the north, and about 40 ft. higher. The rock extending over the site of the pier had to be levelled down to about 7 ft. above high water in order to obtain ground for laying down plant, machinery, and materials. The old battery slip, the ancient landing-place for the ferry boats which slopes down from above high water to a few feet above low water, was covered over with an extensive and substantial timber staging, on which cranes were erected for unloading and moving material, and which also served for landing the workmen and for mooring barges and steamboats. (See Plates IX., XI., XII., and XIII.) Further inland, in convenient situations, wooden huts for the accommodation of the workmen and their families were erected, to which were added, later on, a canteen, stores, and dining and reading-rooms. At South Queensferry the preparatory work was of a much more extensive character. The ground here rises rapidly from the shore at agradientof about 1 in 2 until it reaches an elevation of about 100 ft. above the sea, and thence continues to rise with a gentle slope in a southerly direction. As a great deal of level ground was required here for work- shops, drill roads, and spaces for temporarily fitting together portions of the steel- work, it became neces- sary to level the ground in terraces. Thus the general level of No. 1 Shed is about 12 ft. below the offices, while No. 2 Shed is about 6 ft. above these, the drill roads another 5 ft. higher, and so on. No. 1 Shed was considerably enlarged, and No. 2 Shed at once commenced, as were also the drill roads on which the tubular members had to be put together and drilled. Further to the south still some forty wooden huts were erected, together with stores for the sale of food and clothing, boots, and groceries, and a canteen with dining and reading- rooms. To these were presently added sixteen houses substantially built in bricks for the accommodation of foremen and members of the staff, and about sixty tenements at Queensferry for leading hands and gangers. Next to the drill roads a carpenter’s and joiner’s shop was erected with a saw-bench and a pattern shop, and a large drawing loft, 200 ft. long by GO ft. wide, with blackened floor upon which full-sized drawings were prepared and full-sized templates made for drilling, planing, bending, Ac., of portions of the superstructure. Telephonic communication between offices, stores, workshops, and the Queens- ferry, Inchgarvie, and Fife centres, was established by means of a cable laid across the Forth. On the west side, the ground was bounded by the North British Railway to Queensferry, which here runs in a deep cutting. Two temporary bridges — girders of the ill-fated Tay Bridge — were thrown across at a distance of about 200 yards apart, and as the progress of the work required further exten- sions, ground was taken on the other side of the lines, until finally between 50 and 60 acres were occupied by the works on both sides of the line and right up to the Edinburgh-road. All this ground during the busy years of 1886 to 1889 was covered with girder- work under construction, and presented a striking scene both day and night. Down by the shore to the east of tire central line of the bridge a sawmill was erected, and later on a large cement store. The Queensferry jetty was commenced early in 1883, and completed in the spring of 1884, shortly before the first caisson was launched. It is a little over 2100 ft. long, by 50 ft. wide. It runs parallel with the centre line of the bridge at a distance from it of 60 ft. to about 100 ft. beyond the cantilever end pier, whence it passes by a gentle S curve right into the centre line, and terminates in a strong crosshead which ENGINEERING. embraces the four masonry supports of the Queens- ferry Pier. Extensions of this jetty were made during the building of the foundations and lower portions of the approach viaduct piers, but were removed again after the girders had been completed. A similar extension with landing stage for steam- boats, and storage ground for building material was made round the cantilever end pier, and remained during the whole time. The jetty is built on piles driven in the silt and soft clay down to the boulder clay. Where rock occurs, the uprights are secured on level points by being bolted to stout iron pins which are sunk in holes drilled for the purpose. There are six piles mostly 12 in. by 12 in. baulks, set in a row trans- versely, three on either side being bound together by half-timber cross bracings on opposite sides and the whole connected by a full timber crownhead set on top. These trestles are set about 20 ft. apart, and are held together by raking struts passing from the top of one trestle to about low- water mark of the next. Passing from trestle to trestle are 12 in. by 6 in. rolled joists about 25 ft. long, weighing 56 lb. to the lineal foot ; these are set from 4 ft. to 5 ft. apart, according to position, and transversely on these the planking 3 in. or 4 in. thick, as the case may be, is laid, which forms the flooring. The level of the top of the planking is about 8 ft. above high water. The jetty was erected by means of an ordinary traveller carrying an overhanging pile- driver, which set out the piles 20 ft. in advance and drove them in. The uprights were then cut to level, the crownhead set on, the diagonal bracings and raking struts fixed, and the traveller moved forward on double longitudinals. The joists were laid down behind the traveller and the flooring made up. As this mode of working did not pro- gress as quickly as desired, a pile-driving barge was placed near the far end and worked towards the shore. In the position of the jetty forming the T head, the piles required to be very long, as the average depth at high water was about 32 ft. and the depth of soft mud or silt, some 24 ft., re- quiring piles of from 65 ft. to 70 ft. in length, spliced in the ordinary way. Pointed pile shoes made of malleable iron were fixed to the lower ends. The shore end of the jetty was connected with the under works by an inclined road laid on timber trestles, the gradient being about 1 in 6 b , with an iron girder bridge of about 65 ft. span across the Edinburgh-road. There was a single line of rails and a footpath to one side with a covered box run- ning alongside for carrying the hydraulic pressure pipes, and also a supply of water down the jetty to Queensferry Pier. The incline was worked by a wire rope, l j in. in diameter, drawn by a winding engine on the top. Down this incline all material was sent which arrived by North British Railway, whether fuel, oil, or other stores or plant and ma- chinery, or, finally, steel- work which had been pre- pared in the shops and yards. Upon the jetty itself a number of service lines were laid down with suffi- cient room between, to store immense quantities of building material. Along the east side two lines were laid down which conveyed all the material coming down the incline to three or four heavy steam cranes, by which it was lowered into the the barges and conveyed to the landing stages on Inchgarvie or Fife. While the jetty was in course of construction, launching ways were laid down in a sheltered bay about a hundred yards to the east below, and in front of, the sawmill. They consisted of parallel rows of timbers, of sufficient width to take two caissons of 70 ft. diameter side by side. They were laid to the natural slope of the ground, which is here part rock, part shingle, and lias an easy gradient of about 1 in 11. The launching ways will be further referred to in connection with the build- ing of the caissons. Machinery and plant of every kind and descrip- tion commenced now to arrive on the ground. A siding had been laid down from the works to South Queensferry station, about half a mile distant, and another siding in the cutting alongside the shops. Cranes were set up in all convenient positions, and thus a large amount of material arriving by train could be unloaded close to, and distributed among the different shops. By this arrangement the various sections of raw steel — whether plates, bars, angles, tees, or others — could at once be delivered near the heating furnaces or drilling fir planing ma- chines where they required to be dealt with. From this time forward for fully five years, the plant kept on increasing at an astounding rate, most of it being of a special character, and purposely 225 designed for these works. The list of the plant on the works towards the end of 1888 is a voluminous document, and is represented in the accounts by a very large sum, not far short of half a million sterling Inchgarvie . — The island of Inchgarvie, which Pro- vidence has so kindly placed in the middle of the Firth, is a peak of whinstone rock, about 850 ft. long at high, and 1500 ft. at low tide, and on an average not more than 60 ft. wide above water. The castle stands on the highest part of the rock about 40 ft. above high water, and the square keep is about 30 ft. high ; on the top of this the wind gauges are fixed. The distance from Inchgarvie to the Fife shore is about 1600 ft., while to the Queensferry shore it is rather more than double. Although owned by the Dundas family, whose seat is in Linlithgowshire, the authorities on the north shore claim it as belonging to the County of Fife. The castle was built some time subsequent to 1490, on the 20th of March of which year, King James IV. of Scotland granted a license to John Dundas of Dundas to erect a fortress on the island of Inchgarde, since corrupted to Inchgarvie. The object was to afford protection to all shipping seek- ing refuge from the pirates with which the North Sea seems to have been infested in those days, and for giving such protection, Dundas was authorised to levy a toll of 6d. per ton. One of those persons without belief in the good old days has suggested that the Laird of Dundas not only kept a garrison on Inchgarvie for the protection of the shipping, but that he also provided the pirates in the North Sea for chasing them up the Firth ; though with regard to this both history and charter are silent. The four circular piers are situated at the western extremity, wholly submerged at high water, although a broad ledge of rock is uncovered by the tide at low water. This portion of the island is called Craig Spurry, and upon its north-western point stands a brick pier, about 33 ft. square, and about 7 ft. above high water, the only piece of permanent work built in connection with Sir Thomas Bouch’s gigantic suspension bridge. Upon it was erected, some three years ago, a lighthouse with a revolving light giving flashes about every five seconds, visible for many miles both up and down the Firth. A spring of fresh water was said to have existed on the island, and some 40 yards east of the castle, a square well, partly cut out of the solid rock, partly formed by a brick wall, was found. It was pumped out and carefully examined, but no bore- hole or other inlet could be discovered, and it proved to be simply a storage tank in which the rainwater from the overlying portions of the rock collected. On Inchgarvie the first work in connection with the cantilever bridge was carried out in the erection, during the summer of 1882, of the wind gauges on the top of the castle, and already de- scribed. About the middle of April, 1883, the construction of a landing stage was commenced, of iron girders and iron columns pinned to the rock. At the same time the square keep of the castle, some out- buildings, and the whole of the battlements, were roofed in to afford space for the most necessary shops, offices, and stores, to which was added later on, a substantial cottage and a kitchen, and sleeping accommodation for ninety foreign workmen occu- pied in the sinking of the pneumatic caissons. All over the west end of the island, the rock was cut down to the general stage-level of 7 ft. above high water, and as much ground was made up as could be obtained, by filling up with the debris of excavation and of removal of rock Some 100 yards of sea-wall had to be built as a protection against the heavy breakers rolling in from the east, and every square foot of space thus gained was of great value thereafter, when an immense amount of material required to be stored. In the Act of Parliament authorising the erection of the bridge, the whole of the island had been included in the Parliamentary limits, but at first only the area within the four circular masonry piers, and a reasonable amount of ground for work- ing purposes was acquired. It was soon found that this was quite insufficient for the requirements of the works, and notice of compulsory purchase by the Forth Bridge Company, was given to the proprietor. The matter came to arbitration and was settled in 1884. A sum of 1500L had been paid to the pro- prietor for the right of placing four masonry supports on the island, and in terms of the arbitration a 226 further sum of 2800/.. was paid. The island is now, therefore, the property of the Forth Bridge Rail- way Company. It having been considered advisable to cover the whole area between the piers with staging, a com- mencement was made without delay. Owing to the nature of the bottom, which was all solid rock, it was found more expedient and safer in view of the exposed position, to make this staging of iron, and not of timber. The area of this staging ulti- mately amounted to more than 10,000 square yards, and the weight of iron used in its construction was between 1100 and 1200 tons. In view of this large expenditure for temporary purposes, it was deemed right to proceed on some system in the laying out the main line of girders. As the horizontal tubes, the horizontal girders between skewbacks, and the double cross of diagonal horizontal wind- bracing, required to be carried by the staging before they could be connected with the skewbacks and rivetted up, the main lines of the iron girders of the staging followed the centre lines of these members, the remaining spaces being filled in sufficiently strong to carry any weight which was likely to be put upon them during the erection of the superstructure. As this staging stood well the very severe tests to which it was subjected from various causes, and only yielded to a slight extent in places where it had been absurdly overloaded, it may not be amiss to give a few particulars as to its construction, shown in Fig. 20. The upright columns or supports consisted of four angle-bars 4 in. by 4 in. by 4 in. , braced together on all four sides by double crossbars of flat section, 3 in. by jin., the column being 2 ft. square. A cast-iron shoe, to which the four corner angles were bolted, formed the foot of the column, and it had a large boss in the centre with a 4 in. round hole through which a pin was passed going into the rock to a depth of about 3 ft. The longitudinal main girders were 5 ft. in depth, and consisted of four angles 6 in. by 4 in. by 4 in., two in the bottom boom and two in the top boom, with gussets inserted between every 5 ft. apart for attaching the diagonal bracings, which were angles 6 in. by 3 in. by 4 in. placed alternately on one side or the other. The girders were carried by, and bolted to, cross-angles attached to the supporting columns. The girders carried safely a distributed load of about 6 cwt. to 7 cwt. per square foot up to 30 ft. clear span between supports. The columns were arranged in clusters of four, forming a square, the sides of which were 14 ft. taken at the centres of columns, and such clusters were placed immediately under the points of intersection in the girders of the structure overhead, or in fact in any place where much weight had to be carried. The four columns so placed were braced to each other by crosses of fiat bars of heavy section 34 in. wide by 1 in. thick, the centre of the cross being formed by a heavy ring, the flat bars terminating at that point in 14 in. round with a thread cut upon them which passed into the ring. By a nut on either side of the ring the flat bar — the other end of which was bolted across the column — could be tightened or slackened as desired. Two or three sets of these bracings, according to the length of column, were bolted to each of the four sides of the cluster, the lower ones reaching in most cases to within a foot or two of the bottom of the column having to be put on by divers. Generally speaking these clusters were placed about every 45 ft., centre to centre, and for intermediate supports, where necessary, single columns under each girder were considered sufficient, and these would receive transversely a pair of angle-iron cross- bracings between high-water and low- water mark. The longitudinal girders run through the uprights, spaced 14 ft. apart, and they were braced laterally about every 25 ft. by a pair of cross-angle bracings carried from top boom on one side to bottom boom on the other side and vice versa. All the girders were made in regular lengths of bars, breaking joint at 5 ft. ; they were marked by template and punched, and all parts except those for closing lengths were interchangeable. All holes were punched for §-in. bolts. The girders weighed just lj- cwt. per foot lineal, including all bracings, the columns about 64 lb. per foot lineal, including bolts. The whole staging was erected by overhang with derrick cranes in the following way : Starting from a cluster, the next columns forward would be lowered till they nearly touched the ground, the diver would then descend and examine the bottom, select- ing a nearly level bit, or otherwise dressing the rock roughly. A few bags of concrete were then lowered ENGINEERING. to him, with which he made the bed into which the column was lowered. It was then strutted by one or two light battens to the already fixed work, a 4-in. jumper lowered in the centre of the column, and a hole jumped by means of a spring pole some 25 ft. long. The j umper was lowered through a tube 4 j- in. in diameter, which fitted into a socket left in the cast-ironshoe at thebottom, and acted as guide. The hole was jumped about 3 ft. to 3 ft. Gin. deep ; the jumper was then withdrawn, and a wrought-iron pin, 4 in. in diameter and 5 ft. long was dropj:>ed down the tube. The latter was then lifted up, and the diver descended to ascertain whether the pin had well entered into the rock. When the columns were fast, a length of girder was laid upon them on each side, and the crane advanced another section. Across the longitudinal girders, 12-in. rolled joists weighing 56 lb. to the lineal foot were laid, being 21 ft. to 25 ft. in length, and therefore overhanging the girders from 3 ft. to 5 ft. The joists were bolted to the girders by hook bolts and ordinary draw-washers, and were spaced 5 ft. apart. The decking consisted of 3 in. by 9 in. planking, bolted to the top flanges of the rolled joists by bolts and draw-washers from underneath. The staging, as first projected, was commenced in the autumn of 1883 and finished before the end of 1884, but additions became necessary from time to time to accommodate the immense quantities of material, and at times the 10,000 square yards of staging were found quite inadequate to meet the demands upon it. All portions of the staging which had to be used as landing places for materials — and of such there were a good many — had the iron columns strengthened by bolting on heavy timbers, with half-timber fendering upon that for wear and tear. Horizontal timber struts were also set up against the backs of those columns to guard them against bending in by the action of the boats and barges upon them in rough weather. By the time the staging was up round the north piers on Inchgarvie — these were already well for- ward — arrangements had to be made for the re- ception of the two heavy caissons for the south piers. Facing the south, therefore, two semi- circular openings were left about 73 ft. in diameter, an extra number of columns were placed in the half-circle and well braced with the others next behind, and the whole row of columns between the north and south piers, on either side, were joined together at about low-water mark by a continuous line of double angles to take the thrust from and give resistance to any possible bumping of the heavy caissons during the time they required to remain afloat. Meanwhile plant and machinery were sent here as to the other centres, a number of offices, large workshops, stores and shelters for the men were built ; also engine-houses for pumping engines, air compressors, hydraulic accumulators, electric light machinery, and much more. Transport and Distribution of Material. The supply, the transport, and the distribution of the materials necessary for thebuildingof foundations and piers containing some 140,000 yards of masonry and also of some 55,000 tons of steel, and a more than equal amount of temporary appliances, was no mean task, and required the exercise of much energy and skill as well as tact and patience, for the work was equally pressing on all points, and no one liked to be left behind in that great race for supremacy. Of the building materials, granite, Arbroath rubble, and sand were brought by water, and could, therefore, be unloaded at the various centres where required ; so also could rafts of timber in baulks and planks or battens in barges, and in some instances cargoes of coal or coke, but all the other material had to come down the incline, and for these the jetty at Queensferry was the main centre of collecting and storing, as well as of distributing to the other jetties. The steel for erection, after it had passed through the shops and had received a coating of boiled oil, and its distinguishing markings both in typing and stencilling, was passed down the incline on trollies and charged into steam barges for general distri- bution. For the service of carrying materials were pro- vided, four steam launches for the light work, and eight large steam barges, with a number of ordinary barges or lighters, which were towed by one of the launches or barges. [Feb. 28 , 1890 . For the general service of conveying the workmen from or to, or between, the different main centres, a paddle steamer was hired for some time, which was afterwards replaced by one specially built for these works, and capable of carrying 450 men at a time. The steam barges, which were decked over, and the steam launches, were also used for the same purpose, as well as for the service of the engineers and other officials belonging to the staff. A large number of ordinary rowing boats were also kept in use, one of them, manned by two expert watermen, being attached to each cantilever for the purpose of saving life, should any man be unfortunate enough to fall from the erection. As a matter of fact these boats saved at least eight lives, and they saved fully 8000 caps and other garments which the wind had blown off the bridge. Soon after the works had got into full swing it was seen that the accommodation at South Queens- ferry and North Queensferry and the adjoining villages, was totally inadequate for the number of workmen employed, and arrangements were made with the North British Railway Company to run trains between the works on the south side and Edinburgh, and between the north side and Inver - keithing and Dunfermline. These were all special workmen’s trains and were run at merely nominal fares, the price for an Edinburgh weekly ticket being 2s., or 2d. for a run of over 13 miles. The Dun- fermline tickets were about half that amount. Two trains were run in the morning, closely following one another, and two trains at night, each train bringing a number of men going on their shift, and taking back those who had worked their shift. Some time later the train service was extended as far as Leith. It is worthy of remark that the men living at Leith, and there were several hundreds, had to leave their homes at 4 a.m., in order to be at their work at 6 , and they would not on their return in the evening, reach home again before 7 o’clock, yet they preferred this to the other alternative of living in the overcrowded rookeries of the neighbourhood. In the summer time a steamboat service was also arranged between the South Queensferry Jetty and Leith, via the Firth of Forth, calling both ways on Inchgarvie, and so long as the weather was favourable, this was a most enjoyable, and certainly healthy trip for the tired workmen. On wet and stormy days, when the men had to leave work owing to the weather, these trains were often telegraphed for, to enable them to return to their homes, instead of keeping them till nightfall and leaving them to the tender mercies of the public- houses, of which there were in this place, as in many others, far too many. As it was not possible to so arrange that the work- men living on the south side or north side of the Firth respectively, should be working on the same side, and as the Inchgarvie men also belonged to both sides, it required quite a fleet of steam- boats and barges to convey the men to the points whence their trains started, the more so as this had to be done within a very short time after work had ceased. In bad weather, or during fogs, and on dark mornings and nights, the transport of many hundreds of men — some nine hundred working on Inchgarvie alone at one time — was a subject of unceasing care and anxiety to those in charge, for in addition to the dangers provided by the elements, there was always a number of unruly and reckless men whose conduct brought mishap and injury on others as often as on themselves. Lighting. The efficient lighting of so large a working area, changing every day almost, having not only to be carried forward with the work, but also upward and in all directions, was a task of con- siderable magnitude, and of the greatest influence upon the rate of progress. It is not so much the lighting of the actual spot where work is proceeding, but that of the approaches to these points, and of the accessory places, such as stores, engine-houses, workshops, jetties, and landing-places, which runs away with so large a proportion of the total illumi- nating power. As regards the nature of the lights it was to be expected that a keen rivalry would spring up be- tween the various systems of lighting. South Queensferry has only a small supply of gas, and that at the ruinous rate of 8 s. 4d. per 1000 cubic feet ; this mode of lighting was therefore out of the race. Electricity was at once resolved upon -arc lamps for the shops, and outdoor work, and incan- Fed 23 , 1890.] ENGINEERING 227 descent lamps for offices, stores, fitting-shops, and such like. The latter were also used in the caissons and by divers under water, and proved of immense value in such work. The incandescent lamps were generally of 15 candle-power, but within the last few years, lamps with power up to 500 candles were used for particular purposes. The arc lights were of 1500 to 2000 candle-power, and though every care was used to obtain the best carbons in the market and to keep the machinery going with the utmost regularity, these lights were always unsatisfactory owing to the changes in the colour of the arc and the illuminating power, the glare and flicker and the black and impenetrable shadows thrown by their own framework or by any intervening object. Generally they were arranged in circuit of six or more, and sometimes as many as twenty-one, and the sudden extinction of so many lights caused by the comparatively trivial fact of a belt slipping or a journal heating, was a source of inconvenience and much danger to the men working out on the erection, for while standing one moment in the dazzling glare of these lights they were sometimes suddenly called upon to use their eyes in absolute darkness or sit still. Where the electric light came in as a great and lasting boon was in the lighting of the interior of the air chambers and air shafts of the large pneu- matic caissons while in the process of sinking. The absence of all smoke or filth due to oil lamps of whatever description, the facility with which they excellent light to work by, but if covered with a fine wire guard or a second globe the power of the light is seriously impaired, and if left unprotected, the smallest chip of metal, or even of wood, thrown against it, suffices to cause fracture to the globe and extinction of the light. Except in special cases, where the work is con- fined to a comparatively small area, the writer lias no hesitation in saying that, in the work of outside erection, under the best conditions of lighting, and with every care taken to give the men confidence in getting about their job, the amount of work done at night will not exceed 50 per cent, of that done in daylight. As a consequence of the lighting of the piers at various points and heights, and changing these almost nightly, according to circumstances, there arose a great deal of confusion to the shipping going down or coming up the Firth, and it must be conceded that on a dark night, when, for some reason or other, work was not carried on upon one of the main piers, it was difficult at the first glance to know the exact position of all the piers. On such a night, with a slight mist on, the captain of a tug-boat, coming down river with a barque in tow, mistook the lights on the Fife erection for those of Inchgarvie, and steered his ship straight for the hamlet of North Queensferry, which was hidden in the mist. He perceived his error in time to back his boat out and slip the tow-rope, but the barque continued its course and did considerable damage to itself and to the landing jetty. It is INCH - OARVtE N.W. IRON COFFER-OHM. Section through Shield. INCH-GARVIE IRON COFFER-DAM. N IV. PIER Outside view of Shield number of hands were kept going to attend to the lamps, the dynamo machines, the cables, and other connections. The conductors varied in size from 7 strands of No. 18 gauge wire to 19 strands of No. 16 gauge ; they were supplied by Messrs. W. T. Glover and Co. , of Salford. Materials of Construction for the Masonry Piers. It was laid down in the specification to the con- tract, that all piers, abutments, and arches were to be constructed of masonry consisting of a granice facing, the hearting being of concrete or of rubble masonry. The stipulations as to the quality of the stone, the amount of facing and dressing, and the quality of cement and sand, were of the usual description in contracts of this kind. Granite . — All the granite for facing — whether rock-faced or dressed — was obtained from Aberdeen, with the exception of the large coping-stones, which weighed between 6 tons and tons each, and the necking courses immediately below the coping. These were of Cornish granite and were dressed. The granite is grey in colour generally, and of very handsome appearance, with some slight veins of red granite running through, which, however, rather add than detract from its appearance. The granite was brought, roughly dressed and squared, in specified courses ranging from 21 in. in thickness down to 16 in., and also specified as headers and stretchers, so as to form proper bond with the hearting of rubble masonry or concrete. Coming by water, the stone could, of course, be delivered at the respective centres at once. The granite coping-stones were 4 ft. 6 in. in depth, not less than 3 ft. in width, and set out alternately as headers and stretchers. The capping — that is, the slightly-curved crown of the piers — was set out after the coping had been built, and the correct measure of every stone was sent to the quarry near Aberdeen, each stone being numbered and marked. Rubble Work . — For this a very hard flat-bedded and easily-split freestone — in colour from reddish ochre to purple grey— was brought from Arbroath. It was brought in large blocks up to 4 tons each, and in thickness from 3ft. downwards, but it could be split with ease into slabs not more than an inch thick. Whinstone blocks, roughly levelled on two sides, were also used in rubble work. These were ob- tained either by quarrying in the open or by the excavations for the piers. F or bond courses in all the viaduct and the canti- lever end piers, a hard freestone from quarries in the neighbourhood or extra large whinstone blocks were used. All the rubble could be obtained at a cheap rate, owing to the inexpensive mode of transport in ships and the facilities of unloading close to the piers. Concrete . — For making concrete the whinstone found both on Inchgarvie and at North Queens- ferry was exclusively used. A number of stone- breakers were set up in the last-named locality, where a large quantity of quarry chips were avail- able and close at hand, and the crushers were placed in convenient positions for charging the broken stone into barges or iron skips for transport to the other centres. BEARING OF CAISSONS could be moved, changed, put up or taken down, was of incalculable advantage in places where breathing even the purest air was a task of some discomfort and difficulty, and here, therefore, the electric light reigned supreme. Fiom the drawbacks mentioned above which attached to the electric arc lights, the Lucigen lamps, which were also introduced at an early Period, were entirely free, though their short- comings cannot be overlooked. There can be no ! doubt that for general work of erection they are j the best for light, the simplest to keep in order, and the easiest to attend to. The disadvantages are that they are difficult to keep clean, as a good deal of the oil escajies unconsumed, especially in high winds, and covers girders and staging with a thick coat of slimy oil, making them slippery and unsafe. It is also difficult to get the creosote oil pure and free from sand, grit, and water, which impurities cause the small passages for the oil to choke, while the last frequently extinguishes the ^ light. On the other hand, it is as easily shifted as an arc lamp, and is not nearly so fragile or apt to be broken. Laige incandescent lamps give a steady and most ON ROCK FOUNDATIONS. i true that a glance at his compass would have shown I him that a northerly course instead of an easterly I could not be right; but it was in consequence of J this mishap that it was decided to erect a light- house at the north-west corner of Inchgarvie with a revolving light giving five-second flashes. This light is at an elevation of about 30 ft. above high water, and can easily be seen for twelve miles up and down river. As regards the cost of lighting, it was not easy under the peculiar circumstances of carrying on the work at the bridge to make comparative trials of the lights. At first the balance was much in favour of the Lucigens — the oil costing only id. to vd. per gallon, but as the demand rose so did the cost of the oil, and ultimately it was difficult to obtain it at four times the original price. Electric light installations, consisting of steam- engines and dynamos, as well as air compressors for the Lucigen lights, were put up on the Fife shore, at Inchgarvie, on the Queensferry Jetty, and at the workshops above, the latter being, of course, by far the most important. During the busiest years the lighting arrange- ments required a separate department, and a large The broken metal was passed over screens to obtain the required size for different purposes. The concrete was mixed dry first, and again after the addition of water, either by hand, or, if re- quired in very large quantities, by a very effective mixer of simple construction. The concrete used in open foundations, in the caissons and as hearting behind the granite facing, differed somewhat in its composition according to position; but generally speaking the proportion of cement to broken stone was not less than 4-i cubic feet to the yard of stone, nor more than 6fr cubic feet to the yard, an equal amount of sand, or a slight excess over and above, being added. These quantities were considered as making up one yard of concrete. Such concrete had a resistance to crushing of 50 tons per square foot, and it weighed about 37 cwt. to the cubic yard. t'cmd . — Some difficulty was experienced in ob- taining _ good sharp sand. It, was found in large quantities on both shores of the Firth within half a mile, but objections to its removal being raised by the proprietors of the foreshores, it became ncces sary to send steam barges down the Firth to Kinghorn and Petty cu r, a distance of ten to eleven miles, where the tide lay some banks dry at low water. Owing to the barge having to be grounded 2 28 ENGINEERING. [Feb. 28, 1890. DETAILS OF SOUTH APPROACH PIERS. 1 ?iq. 23 . Inside, View. — S’ 7 - 0 " - h level 210 above' H. IV. Fig. 25. Cross Section. Fig.2j6. Section in centre, line of Bridge, Rail level I56'.0"abwe H.VV- Cantilever Side/ over a tide, a good deal of time was lost, but there was no charge for the sand. Water. Fife . — On the Fife shore the water required was drawn from the mains of the Dunfermline, Aber- dour, and Burntisland water supply ; but this sup- ply becoming scarce, the contractors were obliged to construct a store ge tank above North Queens- ferry. Inchgarvie. — As already stated, no water was found on Inchgarvie, and, after some trials with condensers and filters, it was decided to use the j lower 5 ft. of the holds of two of the steam barges as water-tanks. A large water-tank was set j up on Jnchgarvie, and the water was forced from the holds of the steam barges into the tank by means of pulsometers, the latter being worked by the steam of the barges’ boilers. The water was taken from either the North Queensferry or South Queensferry supply, and this work was generally performed during the night by one or two barges, there being thus a steamboat available all night in case of emergencies. 9838 BB Drinking water was supplied to the people on Inchgarvie in iron boxes encased in wood, holding about a cubic yard — the water being always taken from the Dunfermline mains for this purpose. ENGINEERING. Feb. 28, 1890.] . South Queensferry. — On the south shore the water was drawn from the pits of the Dalmeny Shale Works for boilers and other general pur- poses ; but it proved too dirty, and some rough filter-beds of gravel had to be constructed to pass it through. Thence it was forced by pumps to an overhead tank' set about 60 ft. above the level of the works and shops. This water was conducted in pipes down the incline to the jetty, and, in various leads, all over the works. For drinking purposes another supply pumped from the sand- stone was available; but it proved very inter- mittent, and at times failed altogether. In the summers of 1886 and 1887 a water. famine occurred at South Queensferry, and this was met by the contractors placing large iron tanks at the town harbour and sending a steam barge down the Firth to a place called Starleyburn, seven miles away, where a plentiful supply of water could be got. This was forced into the tanks, and could be drawn upon by all free of charge. In 1887 the united parishes of Kirkliston, Dalmeny, and South Queensferry arranged for a supply of water from the Pentland Flills, and this new supply is both plentiful and of first-rate quality, and lias been running since the summer of 188'°. Cement. The cement used exclusively was Portland cement manufactured on the Medway. This also came by water, but required to be stored for a through a sieve of 400 meshes but letained upon one of 900 meshes to the square inch (20 divisions and 30 divisions to the lineal inch). About 10 per cent, of water had to be added, and briquettes made, which were to be put into water after twenty- four hours and remain in water twenty-five days, when they had to bear a stress of not less than 170 lb. without breaking. For briquettes of neat cement .the breaking stress after four days had to be not less than 300 lb., and after seven days to be not less than 400 lb. per square inch. A few tons of quick-setting or Roman cement were used in making good the joints of the circular iron cofferdams or caissons for the Inchgarvie north piers. This cement is not very strong, but if the joints are well packed with bags of clay puddle and loaded with stones they answer the purpose of keeping the water out for a while. If all preparations are made beforehand, Roman cement can be used in a plastic state, and is thus very useful to divers working under water ; but all the work requires to be done very quickly. Mortar . — The mortar used in the masonry was in the proportion of one of cement and one of sand in the foundations, where rubble-work was used, and one of cement to two of sand in the piers. The pointing in the joints of the granite blocks was done in pure cement. Of the other materials used, except the steel, it may be as well to state here that timber in baulk was brought from Grangemouth, ten miles up river, 229 hillside was commenced somewhat later at level 92 ft. above high water. All the piers on the Fife side are founded on the solid whinstone rock, with the exception of piers 12 and 13, these being partly on whinstone, partly on freestone. All the viaduct piers being on land no cutwaters were built. The rock after being cleaned and examined, and worked roughly into stejDs where necessary, was levelled iqi with concrete and a bed of concrete laid on from 4 ft. to 11 ft. in thickness — this bed projecting all round the granite masonry some 2 ft. Upon this con- crete foundation the first course of granite was set, the form of the piers being rectangular and the curved batter of the pier starting from the bed. (See Plate VIII.) Piers 10, 11, 12 and 13 were built to level 37 ft. above high water, and left, pending the construction of the girders. Generally about Cofferdams. In the description of the pier foundations, frequent use is made of the terms caisson and cofferdam, and to those not conversant with foundation work in water a short explanation may be acceptable. A cofferdam or caisson may be described as an enclosure in water for the pur- pose of laying dry the space enclosed, or, at any rate, of preventing a flow of water through it. In soft ground this is done by driving a double row of piles at a distance of from 2 ft. to 4 ft. from each other, and by continuing to drive piles between those already placed until a double timber wall exists all specified number of days before it could be used. The contractors purchased an old hulk — called while in its prime the Hougomont — in which ten to twelve hundred tons could be readily stored. It was moored off Queensferry, and the ships bringing cement from the south were moored alongside and discharged. From this ship the cement was brought ashore and stored in such quantities as might be required at any time. Subsequently the Hougomont was moored close to the west side of the South Queensferry jetty, and thus a more direct and speedy communication established. While the caissons were being sunk at Queensferry a large number of foreign workmen were lodged on board this hulk, and when, shortly after new year, 1886, an epidemic of small-pox broke out at Queensferry, the ship was towed round into Port Edgar, and moored in an isolated position, and converted into a small-pox hospital. As such it proved of signal service in speedily stamping out the disease. Cement Tests . — The cement is described in the specification to the contract as having to be of the best quality and ground so fine that the residue on a sieve containing 50 divisions on the inch, equal to 2500 meshes per square inch, should not exceed 5 per cent, by weight. It had to be kept in a dry store, and was not to be used until a certain number of samples out of every cargo had been tested. Neat cement was not to be set within less than one hour. Tire weight had to be between 112 lb. and 116 lb. per bushel. For tests, the cement to be mixed with three times its weight of sand which lias been passed Fig. 31. Raft used for survey of foundations. where it was rafted and towed to the works wherever required. Planks, battens, and boards were brought from the same place in lighters. Hardwood, such as oak, beech, and ash, used for packings andother temporary purposes, was got in the neighbourhood and dealt with at the saw-mills. Coal and coke for the three main piers were brought in barges — mostly from Charleston, close by ; but for the shops and yards they were brought by rail. Creosote oil for the Lucigen lamps, and rivet and other furnaces, came in specially constructed tanks by rail. Commencement of the Permanent Work. The positions of the four main piers on Fife being fixed at an early date, a beginning was made with the | excavation of the rock upon the site of the two north piers. The natural bedrock of whinstone rose here to a level of from 10 ft. to 20 ft. above high water, and excavation had to be made to the level at which the foundation or holding-down bolts started — | namely, at 7 ft. below high water. The rock was then levelled with rubble masonry and the building of the granite courses commenced. Excavation was also started upon the site of the | north cantilever pier at a level of about 21 ft. above high water, and upon viaduct piers, 10 and 11, at j 25 ft. and 22 ft. above high water respectively. | These three piers stand on high ground, while piers 12 and 13 were placed at the bottom of the ancient quarry, and were founded at level 7 ft. below high | water. The found at’ons of the abutment upon the round. Sluice doors or valves are placed so as to allow the tide to flow in and out. The single timber piles are held together by h mgitudinal timbers being placed on each side and bolted through, and stays or struts are placed between the walls and across the inner space in all directions to give stiffness and resistance to the water pressure from without. The space between the double walls is now cleaned out as well as can be done, and clay puddle is filled into this space and trodden down hard or pressed down by other means, and this is carried on until the whole space is filled up to and beyond half tide or full tide as the case may be. The sluices can then be closed and the water pumped out from the enclosure, and the bottom upon which the founda- tion is to be placed can be examined, and all necessary excavation made. It depends partly upon the hold the piles have taken of the ground, partly upon the external forces acting upon the timber- walls — namely wind and waves — whether or not the construction of a whole tide dam is advisable. In a whole tide- dam, if tight at bottom, when once the water has been pumped out, the work of excavation — of laying the foundation and building a pier or wall — can be carried on without interruption to the end. In the case of a half-tide dam, the space enclosed can only be pumped dry after the tide out- side has fallen below the level of the clay puddle wall, and the water requires to be admitted so soon as the tide has turned and is rising again up to that level. Work in a half-tide dam is termed tidal work. When working on rock this mode of forming an enclosed space by driving piles is not admissible, ai d o'lier means must be found to keep the vater 230 ENGINEERING out, one of which will be described below. In some cases, whether working upon soft ground or rock, it is not absolutely necessary to lay the bottom dry in order to excavate or to inspect the ground — the latter being done by means of divers and the former by dredging or otherwise. The object of such a dam is to arrest the flow of any current through the caisson while the foundation is being laid, and to deposit the material of which the foundation is to consist — most generally concrete — by lowering it through the water in boxes or skips, the bottoms of which are provided with hinged doors. Finally, if instead of a caisson open at top, the caisson is covered in like a bell or gasholder, and the water is forced out by forcing air in, thereby allow- ing the workmen to enter and excavate in the dry, it is called a caisson worked by the pneumatic pro- cess. In this manner the deep-water foundations of the circular piers were executed, as will hereafter be described, in the case of the two south piers, Inch- garvie, and the four Queensferry circular piers. Inciigarvie North Circular Piers. On Inciigarvie the site of the two north or shallow piers being wholly submerged at high water, and about one-half in the case of the north-east, and three-fourths in the case of the north-west pier, submerged also at low water, the preliminary work was tidal, and between spring tides no work could he carried on at all at this place. When it is considered how exposed the position was there — the work having to be carried on upon a narrow ledge of rock attacked by wind and waves from all sides — it will be understood that the progress could not be very rapid. The conditions of the contract here required that the rock should be excavated in steps, and that the rubble masonry comprising the foundation of the circular granite piers should be bound by an iron belt 60 ft. in diameter and 3 ft. deep; the highest portion of the rock upon which this belt rested to be 2 ft. below low water ; the belt, or at any rate a part of it, to be brought down to form a protection for the foundation rubble masonry upon the lower steps. It was therefore decided to cut a chase 8 ft. wide (3 ft. to the inside and 5 ft. to the outside of the 60-ft. circle) out of the rock where it was higher than 2 ft. below low water, to make the 60-ft. belt of three thicknesses of -i-in. plate, and to carry the centre plate downwards, after it had been cut, in such manner as to fit as nearly as possible the natural contour of the rock. (Fig. 21.) A light staging was, therefore, erected above high water, the correct centre of the pier placed upon it, and by means of a trammel-rod 30 ft. in length, from the end of which a pointed sounding-rod was suspended, a correct reading was taken every 6 in. on the cir- cumference of the 60-ft. circle, after a diver had been round to clear out any loose stones lying in the line, or picking otf any sharp points projecting. These readings were plotted and the centre plates cut to it. In the mean time work had been done upon the chase, and, when nearly cut down to the right level, the belt was put together on the staging exactly above the site of the pier. The plates projecting downward, and forming the shield, were stiffened by T bars vertically over the butts, and, where required to be carried down to a con- siderable depth, as in the case of the north-west pier, they were further stiffened by horizontal circular girders and stayed to the rock by bars of angle-iron. The whole belt was now rivetted up, and, when ready, received two coats of red-lead paint, and was lowered down by means of hydraulic jacks into position. (Fig. 22.) The top edge of the 3-ft. belt was then levelled all round, and corrected where necessary. A heavy angle iron, 6 in. by 6 in. by -g- in. , ran round the inside of the 3-ft. belt, and upon this was now set a single tier of temporary caisson, 10 ft. in height, and consisting of fourteen segments of about 30 cwt. each in weight. This helped to keep the belt down to the rock, and a number of heavy blocks of stone were placed on the top of the caisson for the same pur- pose. A sluice door in the lower part of the caisson was kept open to admit of the tide flowing in and out. Steps were now taken to make good the joint between the 3 ft. belt and the shield and the bedrock. This was done in the following manner: f A number of concrete bags, about 14 in. by 30 in., and 8 in. to 9 in. thick, were prepared and passed down to a diver, who laid them round the outside of the belt at a distance of about 4 in. A second row was next laid round the outside of the first row, and tolerably close up, the space between the two being made up by clay puddle well stamped down. Any split, or hole, or crevice in the rock was also filled with clay. Upon these two lower rows, other bags were now laid crosswise; up oil these, two rows lengthwise, and a fourth row crosswise on the top, which was laid close up to the belt. This was done in sections of about 15 ft. to 16 ft. length all along the shield, but round the outside of the treble belt only two bags deep were laid. On the inside also a single row of clay bags, backed by a row of concrete bags and loaded with stones, was laid round the complete circle. Cement grout, without intermixture with sand, was now prepared and passed down to the diver — but only at slack tide, high water, or low water — who lifted off one or more of the top bags and poured the grout into the narrow sjiace left, until it overflowed. He then replaced the bag and proceeded to the next division until all was done. Forty-eight hours were allowed [Feb. 28, 1890. caused by the action of heavy waves running up to the temporary caisson at low water with great violence, and shaking the whole fabric. The whole of the north-east pier was built in a half-tide caisson, as the work was not pressing ; but in the case of the north-west pier, so soon as the rubble masonry inside had been brought up to low-water level, a second tier of temporary caisson was added, and the work could then be carried on at all states of the tide. While tidal work was carried on in these two cofferdams, the amount of water which had to be pumped out every tide was 250,000 gallons in the one case, and 340,000 in the other. The time occupied was 50 to 55 minutes, but work was, of course, commenced so soon as the higher parts were laid dry. For pumping out smaller quantities of water collected through leaks, pulsometers or small centrifugal pumps were used. The temporary caisson is shown in Plate VI I. A statement of the time occupied in building the foundations of these two piers is given in Table No. II. TABLE No. II. — Progress of Work on Inciigarvie Piers. North-East Caisson. North-West Caisson. Rock excavation commenced ... Lowest point of foundations Caisson and shield ready for lowering Joint between caisson and rock made good ... Caisson pumped out first time... Rubble masonry in foundation commenced... Foundation finished to low water First granite laid Pier completed ... June 22, 1883 26 ft. below high water February 29, 1884 April 2, 1884 April 5, 1884 April 16, 1884 June 1, 1884 June 2, 1884 November, 17 1884 January 13, 1884 33 ft. below high water September 10, 1884 October 17, 1884 October 20, 1884 October 24, 1814 December 20, 1884 December 23, 1884 March 18, 1885 to elapse for the setting of the cement ; the sluice valve was then closed, and the caisson pumped out gradually. When leaks were discovered, the diver descended to examine the outside, and, where necessary, cut out some of the grouting and replaced it by new. As it was not considered that this cement joint would be able to stand the full pressure of the tide rise, the caisson or cofferdam was worked as a half-tide one, it having to be pumped out every tide as soon as the water had fallen below the top edge of the temporary caisson. I 11 addition to the hydrostatic water pressure, the caisson had to stand the heavy seas thrown against it, whether coming from west or east. Under these circumstances, it was often considered advisable not to pump out the cofferdam, lint leave the sluices open and allow the tidal flow free access. Under such conditions, it will be easy to see that, during a season of bad weather, much delay could not be avoided, and though the work of excavation had been commenced in the summer of 1883, it was not till the middle of April of the following year that the first rubble masonry could be laid in this pier. In working the excavation, no blasting was done within H ft. of the iron belt, but the rock was quarried up to within 6 in. and rubble then built in at once. Any steps cut in the deeper portion were invariably at least twice as broad as they were deep. The deepest point to which excavation had to be carried in this pier was at 8 ft. below low water. The cofferdam or caisson for the north-west pier, Inciigarvie, was done in the same way precisely as described for the north-east, only that, owing to the experience gained by the divers and other men engaged upon the work, the progress was much more rapid. In the north-west pier the depth of the shield was 15 ft. below low water, and extended to nearly one-half of the circumference. There were, there- fore, in addition to the vertical T bars which covered the butt-joints of the shield-plates, three horizontal circular girders, carried at a distance of 4 ft. 6 in. from each other, and from these a number of horizontal tie-bars with cross-bars at the ends were carried radially and level to the rock opposite and pinned to it, and afterwards built into the solid rubble masonry. (See Fig. 22.) This mode of making the joint between the rock and the iron belt was simple and quite effective. Most of the leaks were due to natural crevices in the rock, running from the inside to the outside at a considerable depth. These were circumvented by building small clay dams round, and leading the water by a shoot to a pump. Leaks were also Fife South Circular Piers. As the two south piers on Fife were also situated on the sloping face of the rock, and required excava- tion at different depths, a somewhat similar course was followed in the construction of the cofferdams or caissons, but with one important difference. In the case of Inciigarvie the caissons were set on the rock, and secured to it, as far as jiossible, by weight- ing them, and the joint was made good previous to any blasting of rock near the 60-ft. circle being done, except so far as the excavation of the circular chase was concerned ; while in the case of the Fife south piers, diamond-drilling plant under a sub- contract was employed to drill all over the area of the pier and blast the rock before any cofferdam or caisson had been put down. F or this work an iron girder staging was erected over the piers, on which a traveller with running gear from end to end was placed. The depths to which the different steps in the excavation had to be carried was given, and holes drilled to these depths. When a number of holes were ready, they were charged with explo- sive and fired ; but the rock was not removed at the time, and lay there in great shattered masses. The consequence was that when it was attempted to place caissons with projecting shields to fit the contour of the rock, the leaks were of such a nature as to defy any pumping power then at hand. The Fife south-west pier, in which the deepest part was 7 ft. below low water, and in which only a very small portion lay below the level of the circular chase 2 ft. below low water, could be managed with some little difficulty; but in the south-east pier, where the shield had to be carried to 19 ft. below low water, it became necessary to construct a puddle clay dam round the outside of ; the caisson with piles heavily shod and driven into ! the debris of broken rock. Even then the difficulty could only be overcome by collecting together the water from a number of leaks, and by means of | powerful pumping machinery to get the upper hand 1 of it. Rubble masonry was then built in all places \ where running water could be kept off, and the leaks were thus gradually hemmed in, and finally stopped by pouring cement grout into these places at slack water and with the sluices open, in order that no water might be forced through the grouting | before it had set. A large diving bell, with air-lock and the neces- sary machinery to move the bell all over the area of these piers, had been constructed, as it had been intended to form the foundations of concrete depo- sited through the water by hopper-bottomed skips ; but as it was subsequently decided to, have the foundations of rubble masonry instead, it became 231 Feb. 28, 1890.] ENGINEERING. necessary to lay the bottom dry, and the diving bell was never made use of. The north piers on Inchgarvie and the south piers on Fife are founded on the solid whinstone rock. Table III., given below, shows the time occu- pied in building the foundations of the four circular piers on Fife, the depth to which the foundations were carried, and other particulars. strength, for the base upon which this great masonry pier had to be raised was not less than 115 ft. long by 60 ft. wide. It was at first divided into halves by a double row of piles with puddle clay filling ; but, after a good portion of the concrete base had been laid all round the sides of the dam, this partition was cut down, the piles being sawn off flush with the bottom and the con- crete base carried right across. In this pier the TABLE No. III. — Progress op Work on the Four Circular Fife Piers. Fife Circular Granite Piers. 18 ft. above high water, and further work upon hem had to be delayed until the girders had been erected and rivetted up, and were ready for lifting. The dates relating to the building of the piers, the raising of the girders and the quantities of materials used, are given in a summary on another page. Piers 1 and 2 were carried up to level 47 ft. above high water, and the girders built at that level. The south abutment was raised to 119 ft. above high water, and the girder erected at that level on staging reaching close up to No. 1 pier. Preliminary Work in Connection with tiie Inchgarvie South Piers. North-West. North-East. South-West. South-East. Excavation commenced August, 1883. Feb., 1884. August, 1883. Nov., 1883. Lowest point of foundations ... Rubble masonry in foundation com- 7 ft. below h.w. 7 ft. below h.w. 25 ft. belowh.w. 37 ft. belowh.w. menced Nov., 1883 March, 1884 June, 1884 March, 1885 Foundation finished to low water Nov., 1883 April, 1884 June, 1884 May, 1885 June, 1885 First granite laid Dec., 1883 April, 1884 Sept., 1884 June, 1884 Pier completed ... Sept., 1884 Jan., 1885 August, 1885 South Approach Viaduct Piers. On the South Queensferry shore the founda- tions of piers 3, 4, and 5 were first started, as they were all dry at low water. These three piers are founded on the freestone rock prevalent in ridges all along this shore. Tidal work had to be resorted to without any protection by cofferdam or caisson, and all that was required was to remove the soft or rotten portions of the rock and cut flat steps into any sloping faces met with. The hollows were then levelled up with concrete, and upon this a concrete base was laid enclosed by planking. When this had properly set the granite masonry was at once begun. The concrete base was 61 ft. long by 31 ft. wide, and was the same for all viaduct piers from 3 to 9. The thickness of this concrete foundation varied according to position, from 4 ft. in the shore boulder clay at bottom was found nearly dry and extremely tough to handle, and it gave an indica- tion of the ground into which the large caissons would have to be sunk. Table IV. , given below, shows the levels at which the foundations were started of all the viaduct piers from 1 to 9, of the south cantilever pier, the north cantilever pier, and the abutment, as also the nature of tiie ground under foundations. Figs. 23 to 28 show views of the cantilever end pier and the viaduct piers, with the principal dimen- sions. The cutwaters with a coping of dressed granite reach to the same height above high water as the circular piers, namely 18 ft., and up to this level all the piers from 3 to 9 were built with a hearting of concrete ; above this level the granite was backed by masonry of Arbroath rubble in cement carried up to the top. The hearting in piers TABLE No. IV. — Particulars of Foundations for Viaduct and Cantilever Piers, and Nature of Ground. For General View of Piers see Plate III., Figs. 1 and 2. Level of Foundations referred to High Water. Nature of Ground. South abutment 109 ft. above Blue clay Approach viaduct pier 1 32 ft. ,, 2 7 ft. ,, Freestone rock 5 » ° 13 ft. 6 in. below „ „ 4 14 ft. 5? 5 ? 5 17 ft. 1) It b ... ... ... ... 22 ft. 30 ft. „ „ 8 32 ft. 6 in. , , Hard clay ,, ,, 9 Cantilever end pier, south 38 ft. ,, Boulder clay 33 ft. 6 in. ,, ,, ,, north Approach viaduct pier 10 21 ft. above 25 ft. ,, Whinstone rock » „ 11 22 ft. ,, „ „ 12 7 ft. below Part whinstone t j l'J ••• ... ... ... North abutment 7 ft. , , Part freestone 92 feet above Whinstone rock piers to 11 ft. in No. 9 pier. Piers 2 and 1, as 1 and 2 was of concrete up to the level at which the also the abutment, were situated on the hillside. ! viaduct girders were erected — namely, at about The first was founded on the freestone rock ; 1 47 ft. above high water, from this level to top they but the other two were placed on a stift blue clay | were, like the other viaduct piers, built with a of sufficient solidity. Pier 6 required the con- hearting of Arbroath rubble. struction of a cofferdam, the bottom being rock 1 To facilitate the building of these piers, staging with a thin layer of gravel and clay. Owing to j was erected alongside and connected with the this the cofferdam could not be carried to more i jetty, and cranes were set up to lift the granite than half-tide, the difficulty being to get the piles ; blocks from the jetty adjoining and deposit them in to hold._ A great deal of trouble was experienced j their places. Ail materials were brought along the with this foundation through the want of a tight ! jetty, where also the mortar was prepared and the joint at bottom ; but it was, of course, only a j concrete mixed. Two courses of granite were matter of patience and perseverance. The founda- 1 generally laid, and the hearting of concrete filled in. tion of pier 7 also caused some trouble owing to the ' The mortar used consisted of one part cement and same difficulty at bottom, and a half-tide cofferdam j two parts sand. had to be used ; but in the foundations of piers 8 The concrete consisted of 27 cubic feet, or and 9 the layer of clay at bottom was of sufficient 1 cubic yard of broken whinstone, 51- cubic feet of thickness to allow good piling to be done, and cement, and 5.1 cubic feet of sand, mixed dry by whole-tide cofferdams could be constructed. Pier hand and then cha'-ged into a concrete mixer where 7 is founded on the rock, but piers 8 and 9 are 1 the water was ad led. From the mixer it was founded on the hard clay. . ! delivered into banows and tipped where required. The south cantilever pier required a cofferdam | All the south viaduct piers from 3 to 9, and the of abnormally large proportions and of great south cantilever end pier, were built up to a level of It has already been mentioned in the descrip- tion of the Inchgarvie staging, that places were prepared for the reception of the two south caissons presently to be brought across from the Queens- ferry jetty. In order to obtain at an early date a correct idea of the contour of the rock upon the sites to be occupied by the two south piers on Inchgarvie, a circular raft was constructed of timber balks decked for about 10 ft. round the outer circum- ference, with 3 in. planking. The raft is shown in Fig. 31. It was made sufficiently strong to resist the action of the waves in an ordinary breeze of wind, or to bear, if necessary, the strain of being beached on shore in case stormy weather should set in. It was a little under 70 ft. in diameter, and the surface of the planked space was 6 in. above water. Large mooring blocks were laid at some distance on three sides, the fourth being attached by cable chains to some of the iron columns of the staging. Upon the raft four crab winches were placed, by means of which either of the mooring chains could be hauled in or slackened. The raft could thus be easily placed in any desired position within tolerably wide limits. A central staff was fixed upon the raft, and about a foot from the outer edge a ring of gas-pipe was laid down upon which the grooved wheels of a carriage ran true to the centre of the raft. A drum was placed upon the carriage, some- what overhanging the edge of the raft, and upon this drum the sounding line was coiled. This con- sisted of a fine steel wire and a long weight weigh- ing about 60 lb., with a point at bottom, feet and inches being marked upon the wire by copper tags attached. Two theodolites — one in the centre line of the piers longitudinally on the iron staging, the other on a masonry pier at right angles to the centre line, but in line with the centres of the two south piers —were stationed to check the position of the centre of the raft every few minutes, while alterations in the tide level were observed on two tide gauges, and recorded. Owing to the heavy current running at this point — both during ebb and flood — the raft could not be held in position with any degree of accuracy, nor could the sounding line be kept plumb in spite of the heavy weight attached. Soundings were therefore only taken during slack water — that is, for about an hour before and an hour after high water or low water. After the actual contour of the rock, on and within the two 70-ft. circles, had been taken, the raft was shifted about in various directions and further soundings recorded, the exact position of ENGINEERING. [Feb. 28, 1890. THE PNEUMATIC CAISSONS; QUEENSFERRY. the centre being always fixed by the two theodolites reading angles from fixed stations. The whole area for about 40 ft. or 50 ft. round the two caissons was thus sounded, and a very fair idea of the contour of the bottom obtained. About 3000 soundings were thus taken, representing a large amount of work and trouble with the sounding gear, the mooring chains, the winches, and last, though not least, with rough weather, and distortions thereby produced in the raft itself. The raft was also used for fixing the guide piles or columns against which the caissons would come to lie, and, as a precautionary measure, the centre was set 1 ft. up the slope of the rock, as it was tolerably certain that during the sinking operations the caisson would slide away from the newly cut face. As soon as the soundings had been taken, and the guide columns fixed for the reception of the caissons, heavy mooring blocks were laid down to the south- east, south, and south-west, with heavy cable chains attached, the ends of which were temporarily secured to the staging. Two stout wire hawsers were also prepared to pass round the caissons as soon as they would be placed in position. To hold the caissons with some amount of security when once they would take the ground, and give them a good bearing all round the edge, it had been decided to place a large number of sandbags upon the rock, and bring these up to the same level — and somewhat above even — as the highest point of rock the cutting edge of the caisson would be likely to touch. In order to still more securely fixthis bed of sandbags, two rectangular piers were built up first of bags filled with concrete, and these were placed (see Figs. 29 & SO) opposite the highest point of the rock on the circumference of the 70-ft. circle. The concrete was of good strength, there being 27 cubic feet of stone to 4i cubic feet of cement and 4| cubic feet of sand. It was mixed dry, slightly wetted, and at once filled into bags. About twenty- six of these went to a yard, and they were put into boxes with hinged bottom and lowered down by a steam crane and emptied. They were put together by a diver, and, when a couple of feet of pier had been built, a number of sandbags of much larger size were put all round it to keep it in place and prevent the tide from washing out the cement. When the concrete piers had been completed, the remaining space under the cutting edge was laid with sandbags, except in two or three places where channels were left through which the air could escape, and through which also the sand- bags and other debris could be pushed down the rock during the sinking of the caissons. In two places well within the air-chamber, and near where the centre of the caisson would come to be, two piers of sandbags were built up upon which the ceiling of the air-chamber would be supported. It remained now to lay down the pipes for the Feb. 28, 1890.] ENGINEERING. ! 33 THE PNEUMATIC CAISSONS ; QUEENSFERRY. HalF Plan on line C. C. supply of air and water, and the electric light cables for immediate connection with the caissons as soon as they should be moored in place. Preliminary Work in Connection with the Four Queensferry Caissons. Over the area to be occupied by these four cir- cular piers, and to some extent outside and round it, a number of soundings were taken to ascer- tain the depth of water, of mud, of silt, of soft clay, and of hard clay. These data are given in another place. The T head of the jetty, which had in the mean time been completed, left four corner spaces free for the reception of the cais- sons, and strong timber dolphins of treble and quadruple piles were placed on three sides of the space left. As the tide currents are not nearly so strong here as on Inchgarvie, and as the caissons would almost immediately touch the soft ground during low water, the danger of their getting away was much less here, and no outside moorings were therefore provided, but strong chains fixed to the piles, and ready to be attached to lugs rivetted to 23 4 ENGINEERING. the caissons, and stout ropes and wire hawsers to pass round them, were kept in readiness. Air compressors, electric light machinery, over- head water tanks, pumps to supply the same, steam cranes, and other plant, were got ready, and large quantities of broken stone, cement, and sand were stored close by for use. Water pressure at 1000 lb. per square inch was brought down the incline from the accumulator on the top, and con- ducted to the end of the jetty. The Pneumatic Caissons.— The six caissons which were sunk by the pneumatic process were mainly built of wrought iron, and were in the first instance constructed and put together by Messrs. Arrol Brothers, of Glasgow — namesakes, but otherwise in no way connected with Messrs. W. Arrol and Co., of Dalmarnock Iron Works, Glasgow. These caissons were taken to pieces again and sent to Queensferry to be built up and rivetted, as here- after described. Description of the Caissons. — The four caissons of the Queensferry group are all of one design, differ- ing only in height. There are two shells, carried up at distances varying from 7 ft. at bottom to 4 ft. 6 in. at top from each other. (See Figs. 32, 33, 34, 35.) The two Inchgarvie caissons, although externally the same in appearance, differ in so far as the inner shell is only carried up as far as the top of the cylindrical portion, being replaced above that by a backing of Staffordshire blue bricks built in cement, which was carried up in proportion as the caisson was sunk below low water. (See Fig. 36.) Generally speaking, the caissons are made up of two parts — the cylindrical and the taper part. The cylindrical portion is of varying height, with a slight taper upwards to facilitate the sinking. This por- tion is 70 ft. in diameter, and above it is the taper part, which is 24 ft. high in all cases, and terminates with a diameter of 60 ft. at top. The lower, or so-called cutting edge of the caisson, is stiffened by a stout double angle and by a broad steel belt, 18 in. wide, and 1 in. in thickness. At a height of 7 ft. above the cutting edge an air-tight floor is formed which extended over the whole area up to the outer skin or shell. From this floor upwards, started the inner shell of the caisson, about 56 ft. in diameter; and here also, but downwards, started the sloping plates, which terminated at the cutting edge, and which were backed and held by a number of triangular brackets set against the floor to one side and against the outer shell to the other. A circular space of tri- angular section was thereby formed, access to which was had by manholes cut into the floor between every two brackets. Under the floor a space was thus left of the form of a truncated cone '70 ft. at bottom, 56 ft. at top, and 7 ft. in height, which was called the air-chamber or working chamber. Its function was to act as a diving-bell for the purpose of gaining access to the bottom of the river and carrying on the necessary excavation over the area thus made accessible. The triangular space sur- rounding the air-chamber was called the shoe, of which the lowest part, as already said, formed the cutting edge. The roof of the air-chamber was supported by four strong lattice girders 18 ft. in height, and reaching from side to side of the inner shell, but being carried through to the outer shell by means of bulkheads or plate diaphragms set between the two shells, and rivetted through with the end posts of the large girders. At right angles to these latter were carried plate girders 3 ft. deep, and spaced 4 ft. apart, centre to centre, all over the ceiling of the air-chamber. The floor plates were so arranged that their joints, where it could lie done, were butted immediately under the centres of these girders, the bottom flanges of which acted as covers on one side, while there were covering flats on the other side. Between the shells, the stiffening was obtained by circular lattice girders, which consisted of angle rings attached to both the inner and outer shell at every plate joint, and of angle bars set radially and attached to the angle rings by gusset plates, and also by inclined angle struts which passed from the angle ring attached to the inner shell to the next higher ring attached to the outer shell. The top of the caisson was formed of a horizontal circular plate girder upon which the temporary caisson was set and bolted down, the joint being made by india- rubber cording about 1 in. in diameter. As already stated, the inner shell in the Inch- garvie caissons was not carried up to the top, but terminated with the cylindrical portion. To make up for the loss of strength a circular plate girder about 2 ft. 8 in. deep is carried right round at this place, similar girders being placed at the second plate joint below, and at every second plate joint above, all these circular girders being combined by vertical angles about. every 6 ft. on the circum- ference. (See Fig. 36.) Three holes about 3 ft. 7 in. in diameter were cut into the ceiling of the air-chamber at convenient distances, and here were inserted three air-shafts, the lower edge projecting into the air-chamber about 6 in. They were made up of lengths of 8 ft, each, with an angle hoop rivetted on at top and [Feb. 28, 1890. bottom, forming the flanges. Two of these shafts were used for the removal of the debris of excava- tion, the other for the ingress and egress of the workmen. In the Queensferry caissons the shafts were pretty evenly distributed over the area of the working chamber, the reason being that in these caissons, as soon as they touched ground, work could be carried on all over the area at once. In the case of the Inchgarvie caissons, only two shafts — one for men and one for material — were used, and these shafts were close together at one side, because most of the work there had, owing to the sloping face of the rock, to be carried on near the point where the cutting edge first touched the rock. In Feb. 28, 1890 ] addition to the air-shafts, a number of cast-iron pipes were fixed, reaching from the air-chamber ceiling to various parts of the outer shell, and these were used for the removal of silt and soft material, all of which, in combination with water, were ejected by means of a small quantity of compressed air being allowed to escape. In the air-chamber itself, the main difference be- tween the Queensferry and Inchgarvie caissons con- sisted in a different arrangement of the shoe. In the former, the sloping plates were carried right down to the cutting edge, while in the latter they only went half-way down the slope, being then bent in a horizontal direction, and brought to the outside shell and then rivetted on. For the sup- port of the lower remaining portion of the outer shell, strong brackets were fixed about 3 ft. 6 in. apart on the circumference, and these terminated at the lowest angle, which, with the 18-in. steel belt, formed the cutting edge of the caisson. This was done in order to allow the sinkers the fullest access to the rock immediately under the cutting edge, it being of the greatest importance that it should be undercut to the extent of at least 0 in. all round. The section of the Inchgarvie shoe is shown in Fig. 52. It has already been stated that launching ways •vere laid down on the south shore to the east of the jetty. These timbers (Fig. 37) were laid on the natural slope of the ground, holes being dug at intervals which were filled up with concrete, and thus provided strong piers to carry the weight of the caissons. At the higher end of the timbers several trestles were set transversely, of such height as to keep the work out of the reach of the water. The tops of the trestles formed the platform upon which the construction of the caisson was com- menced and carried on until about 25 ft. or 30 ft. of it, counting from the lower edge upwards, had been built. The weight was then about 300 tons. By means of hydraulic jacks the caisson was then slightly raised and packed, and the trestles withdrawn. It was then lowered down to within half a foot of the top of the launching cradle. This was made up of transverse girders laid on longi- tudinal timbers, which in their turn were laid on the timbers forming the launching ways. The top of the cradle was, of course, horizontal, and it was essential to support on it as large a portion of the ceiling of the air-chamber as could be reached, and also as much as possible of the lower or cutting edge of the caisson, which latter was also supported for the time being by a number of timber blocks placed on the ground. Building of the Caissons. In the building of the caissons, the general prac- tice was to commence by laying down the bottom booms of the large lattice girders upon the timber trestles at the head of the launching ways, to bolt the 3-ft. cross-girders between them, and fix to both the fioor-plates. Outside the trestles, any projecting parts of the caissons were supported from the ground by timbers. The plates forming the inner shell were next put on, and also the sloping plates forming the shoe, the two forming one joint with the floor-plates. All joints were rivetted up as far as possible by ordinary hydraulic rivetters, and meanwhile the bracings of the big girders were put on and the top booms laid on these, and more plates were added to the inner and outer shells. Upon the girders the first platform was laid down, and a hand crane set up as well as forges, concrete mixer, and other gear. By the time the caisson was about 25 ft. high — much of the lower work being then done — it was got ready for lowering, as already described. It was even then still accessible in the lowest portions soon after half-tide for further work and for making preparations for launching. Previous to this, all joints in the plates forming the ceiling — the slopiing face of the shoe and the outside shell of the caisson — were carefully caulked to make a good water-tight job. In all cases, previous to launching a caisson, the shoe and the whole space over the ceiling of the air-chamber were filled up with concrete, the latter generally to a depth of from 4 ft. to 6 ft. This not only acted as ballast, but it gave much stiffness to all the lower portion of the caisson, and produced a draught of from 9 ft. to 10| ft. after it floated. When finally the caisson had been built to the required height and weight, all the points of con- tact between cradle and caisson were carefully adjusted, and all the weight allowed to rest on the cradle, it being then ready to be launched. The ENGINEERING. cradle was loaded with pieces of iron to hold it down to the launching ways when the water lifted the caisson off its bearings and floated it away. The slope of the launching ways being about 1 in 11, it required a push from a 12-in. hydraulic jack, placed horizontally, to set the mass in motion, and this it did most effectually on all occasions. The launching of these caissons took place generally at or near to the time of high water of spring tides, owing mainly to the shallowness of the shore in front of the launching ways — the caissons drawing from 9 ft. 6 in. to 10 ft. G in. of water at the time. As soon as afloat a tug-boat was attached and the floating monster at once towed to its final resting-place, or else to the end of the jetty, where conveniences existed for charging concrete into it and placing all the neces- sary machinery on board, as also the temporary caisson on top. Should any tide not rise as much as was expected, it was the practice to hermetically seal the air-shafts and other outlets from the working chamber and force air into the latter, in order to increase the buoyancy. The first caisson — that for the south-west pier, Queensferry — was launched on May 26, 1884, the ceremony being performed by the Countess of Aber- deen, the Earl being at the time Lord High Commissioner to the General Assembly in Edin- burgh. The last caisson was launched on May 29, 1885 — the south-west Inchgarvie. AIR-LOCKS. The Temporary Caissons . — The temporary cais- sons, placed on the top of the permanent ones for the purpose of keeping the water out while the circular granite pier was being built, were of the same construction as already described in connec- tion with the Inchgarvie north piers. (See Figs. 32 and 51.) The lower tier of caisson segments, in addition to the large number of small bolts which made the water-tight joint, had two long 2-in. bolts to each section of caisson, or twenty-eight bolts on the circumference. These bolts terminated at top in a screw thread with nuts, and at bottom in a long shackle, which grasped a lug rivetted to the out- side of the permanent caisson. The temporary cais- son was made large enough to allow space round the completed pier for the masons pointing the joints in the granite blocks. Two tiers of caisson — total height, 20 ft. — were generally held sufficient to keeji out the water ; but in places where rough seas and much spray were likely to occur, a third tier, or at any rate a portion of it, was put on. The south- east caisson on Inchgarvie had a special temporary caisson constructed for it, consisting of plates 22 ft. in length. (See Figs. 36 and 53.) The four Queensferry caissons, after being launched, were at once towed out and placed in their proper positions, being secured to the jetty in such a manner as to allow their rising and falling freely with the tide. The Inchgarvie caissons, on the contrary, were merely placed in a temporary berth near the end of the jetty, and they were completed there, and had the temporary caissons 2 35 _ put on and all necessary machinery placed inside, before they were removed to their p irmanent places. This was done, not only because it was essential that these caissons should touch ground as soon as pos- sible after their arrival in their berths, but also because a large proportion of the machinery inside and of the temporary caissons, was taken from the Queensferry piers, then already built up to above high water, and put on board, and the transport and double handling thus saved. It may not be amiss to state, as an instance, that the last caisson — No. 6, or south-west Inchgarvie — was launched on May 29, 1885, weighing a little over 500 tons, with a draught of 10 ft. 3 in., was towed to Inch- garvie on July 16, drawing 31 ft. of water, and weighing 2877 tons, which was made up as fol- lows : Tons. Permanent caisson... ... 457 Temporary caisson (two tiers) ... 65 Two air-locks, air-shafts, concrete mixer, boiler, steam crane, Ac. 35 Timber floors and staging... ... 50 Concrete ... 1418 Brickwork ... ... 852 Total ... 2877 Before entering upon the description of the mode of sinking the caissons, some account is needed to be given of the apparatus and machinery in con- nection with that part of the work. Air Compressors. There was nothing 111 these different from any ordinary type of compressors. They consisted of a pair of horizontal engines coupled, and directly acting upon a pair of double-acting air-compressing cylinders. There were two pairs of 16i-in. cylinders with 2-ft. stroke, and three pairs of 12-in. cylinders with 2-ft. stroke, all working at 60 lb. steam pressure. They were run up to any speed required to produce the necessary maximum pressure, which in the case of Inchgarvie on one occasion amounted to 37 lb. per square inch in the air-chamber of the south-west caisson. The air-compressing cylinders were water- jacketted, with a continuous current of cold water passing through. For the service of the rock drills inside the working chamber, a separate engine was used, which forced air down by a separate pipe lead at 70 lb. per square inch — the rock drills receiving, of course, the benefit of the difference between that pressure and the prevailing one in the air-chamber only, as they had to discharge into the general pressure of the working chamber. On the top of the men's air-lock a whistle was set which worked by air pressure and which could be regulated from below; by means of this a constant communication was kept up, and more or less air pressure put on in accordance with requirements. The pipes supplying the air were laid from the compressors straight to the caisson side, but the joint to the pipes inside the caissons had to be made by a long piece of flexible tube, the end of which was attached to a check valve placed upon the air- lock for the admission of the men. The air was forced down this shaft into the working chamber, thus preventing the ascent of any foul air in these parts. A supply of water for flushing purposes was also laid on, being taken from an overhead tank set about 40 ft. above the level of the staging. Of great importance both for the safety and con- venience of the men, and for the progress of the work, were the air-locks. Those by which access was got to, and exit from, the air-chamber, consisted of an inner portion, 3 ft. 6 in. in diameter, in con- tinuation of the ascending shaft, and a circular space all round it about 21 in. wide and 6 ft. high. (See Figs. 38 and 39.) The outer chamber was divided by two partitions into two equal spaces. Each of these spaces was provided with a square door giving com- munication on the one side to the air-shaft, and on the other side to the outer atmosphere. All doors opened to the inside. To gain admission to the air-chamber it was necessary to enter one of the outer spaces, to close the door (which was pressed against an india- rubber joint), and by turning a small cock to gradually admit compressed air. As soon as the pressure on both sides of the door leading into the air-shaft was equal, this latter fell open and the air- chamber could be reached by an iron ladder fixed in the shaft. To return from the air-chamber to the outside was the reverse of this, the pressure from the outer chamber being exhausted by opening a small cock communicating with the atmosphere. A, B- LOCKS ON CAISSONS COB ADMITTING AND REMOVING MATERIAL ' Feb. 28, 1890.] ENGINEERING. 2 37 AIR - LOCK AND HOISTING GEAR FOR CAISSONS. Fij. 4 1 to the under side of the upper door and sliding out and in with it, thus bringing the point of sus- pension immediately into the centre of the shaft. set up near the lock so as to centre the air-shaft with its heaving chain ; the top door of the lock was then drawn back and the skip or bucket, about 3 ft. in diameter and 4 ft. high, holding about 1 cubic yard, was lowered down into the lock and the shackle of the inside winding chain attached to it. The upper door was now closed, and a slight turn of the engines tightened the chain and lifted the bucket just clear of the lower door. A cock, or valve, which communicated with the compressed air in the working chamber, was now opened and pressure thus admitted to the lock. The sliding doors were provided with india-rubber joints, and small thumbs or tappets, actuated by a lever, were used to force the door hard up against the india-rubber, in addition to which the gradually increasing air pressure helped to close the joint. When the upper door was thus secured, a turn of the inter- locking wheels set the lower door free ; this was ; now drawn back, and the bucket was lowered right The mode of working these locks was as follows : A down to the bottom of the working chamber, and 3-ton steam crane with fixed jib (see Figs. 36 and 51), j there filled with the spoil of the excavation, or else but provided with quick-moving slewing gear, was the chain was taken off and attached to one already ENGINEERING. [Feb. 28, 189c. filled. A signal was then given, the bucket was drawn' up into the empty lock, the lower door closed, the compressed air let out of the lock, the upper door drawn back, the winding chain taken off, and crane chain attached, the bucket drawn up and discharged on a shoot over the side of the caisson, and the same process repeated as before described. In the drawing shown (Fig. 41) it will be noticed that the bucket in its ascent in the lock touched a lever, and gave indication of its whereabouts by a steam whistle ; but, as an addi- tional precaution, small wheel gear was placed in connection with the winding drum-shaft, and, by means of a dial and pointer, indicated the position of the bucket at all points of its course. The lever K acted upon the long rod L, which was so arranged thatone of its ends was always within a hole drilled in the frames of the sliding doors, and that thereby either one door or the other was made absolutely immovable. The two valves admitting water to the rams working tire sliding doors are seen at D D close together ; each carried a handwheel, out of which a segment is cut, and into this the rim of the other wheel fitted. In the position here shown the upper valve is closed, and its handwheel cannot be turned unless the handwheel of the lower is turned round to bring the cut-out segment exactly opposite. In that position, however, the lower valve would be closed, and it is, therefore, easy to perceive that, so long as the handwheels remained attached to the valves, it was impossible to open both simultaneously. Since no workmen passed through these locks, it was not necessary to admit or discharge the air pressure by degrees ; the inlet and outlet cocks were, therefore, large, and acted expeditiously to reduce the loss of time. Accident to No. 4, or Queensferry North- West Caisson. This caisson was built and launched in the usual way and towed into position at the north-west corner of the Queensferry jetty in December, 1885. It was secured to the staging in the usual way, allowing it to rise and fall with the tide pending the putting on and rivetting of the remaining courses of plates at top, and the otherwise com- pleting it for the sinking process. Owing to the inconsiderable depth of water, the cutting edge touched the mud soon after half ebb, and embedded itself at low water. On New Year’s Day, 1884, an exceptionally high tide occurred, followed by an equally exceptional low ebb, and the caisson sank deeply into the mud, assuming, no doubt, some- what of a list or dip in accordance with the natural elope of the mud. The cutting edge entered so leeply into the more solid portion of the mud or silt that, on the flood tide returning, the water could not get underneath, and the caisson failed to rise with the tide. Not being built high enough, the water soon flowed in, and filled it completely ; and on ebbing, as the lower sluice valves could not be got at, the caisson became top-heavy, and tilted still more over towards the low side. At last, it began to slide in the same direction, and moved thus for about 20 ft., when it stopped. In this position the lowest portion of the top plates re- mained fully 6 ft. under low water, and it became necessary to arrange to add to its height before pumping could be resorted to. A number of divers were employed to bolt on two or three tiers of plates. Arrangements were made to stiffen the caisson internally by timber struts on top, and to keep on stiffening in the same manner as the pumps suc- ceeded in reducing the water level inside the caisson. Unfortunately, the pumping was carried on at too great a rate for the carpenters who were to put in the strutting, and the thin plating could not support the pressure of the water from outside. The plates gave way, and a great rent, right across the lower side of the caisson, some 25 ft. to 30 ft. long, was the result. After dis- cussing many plans suggested for getting out of this difficulty, it was resolved to construct a sheath or barrel of 12-in. timber balks all round the caisson, to bolt as many of these balks as could 1 ;e got at firmly through the iron skin, and to make the best joint that could be got either by puddle clay or cement grouting, or a combination of both. All this work below had to be done by divers, and there ore required a considerable time in doing. In the first instance, a heavy circular timber frame was placed inside the caisson near the top and Tutted in all directions. A number of balks were first placed all round, and, where necessary, driven down into the soil as far as required. Strong iron hoops or belts were laid round all these, and then the filling between these guide timbers carried on, all of them being V grooved on the one side, and the other side V shaped to fit the groove. Finally, wedge piles or closing piles were driven in between the other balks, and as many as could be got at were bolted tight up to the skin of the caisson where it was sound. Nearly ten months had elapsed since the accident occurred before the tim- ber barrel was in such a condition that pumping out could be proceeded with (see Fig. 40). The ground under the high side was now dredged away, and both air and water were forced down the air- shafts into the chamber to wash or force out as much as possible from underneath. Pumping was then commenced, all leaks as they showed being dealt with in any suitable manner, further stiffening inside resorted to where necessary, and thus, step by step, the lost ground fought for. Weight was also added on the high side by commencing to build a brick casing against the outer shell. Patiently this work was persevered with, and at last, one Sunday morning, October 19, 1885, some- piers on Inchgarvie and the four piers at Queens- ferry. The two former are founded on the solid rock, sloping here at an angle of about one in five to the south-west ; while the four piers at Queens- ferry are placed on the boulder clay which is found there in a very hard and solid state at a minimum depth of 48 ft. below high water. The boulder clay here is sloping to north-north-east, also about one in five. These caissons were all sunk by means of the pneumatic process at considerable depth under water, under some difficulty, and under great pressure of air. To manipulate these cylinders of immense size, weight, and height, in the face of the uncertain conditions of wind and weather, and under the influence of a strong tidal current ; to put them— weighing between 3000 and 4000 tons — into their places, and to hold them there and pass them down through material ranging from soft mud to hard rock, was certainly a most formidable task. Yet, with one excep- tion, just above mentioned, namely, the tilting of the Queensferry north-west caisson, these huge cylinders caused proportionately less trouble and anxiety than the shallow cofferdams of the other foundations. This was, no doubt, owing in a great 1 measure to the practical knowledge and expe- Fio. 40. Tilted caisson at south queensferry. what unexpectedly, the caisson raised itself out of its muddy bed and floated once more. It was at once drawn into position, and no time was lost^ in commencing the sinking process. As it uas im- possible to place a new shell in the place where it was rent, it was decided to leave this alone, and not to proceed with the building of the inner shell eitliei , but to substitute for both a stout lining of clinker bricks built in cement. The shape of this and its strength are shown in Fig. 47 . The three other Queensferry and the two south Incligarvie caissons had in the mean time been sunk to their full depth, and in fact had nearly dis- appeared out of sight, and all machinery and apparatus were available for dealing with this the ^ Before the middle of February, 1886, this prodigal among caissons had joined his brethren far down°iii the prehistoric clay, and there is no reason to think that the masonary pile which stands on it is less able to carry its due share of the enormous load laid 011 them than either of the others. The foundations of the four circular piers on Fife, and of the two circular north piers on Incli- garvie, have been fully dealt with, and it remains to describe the mode of founding the two soutu rience of the men in charge of this portion of the work. The sinking of these six caissons was let as a sub-contract to M. Coiseau, of Paris and Antwerp, whose large staff of men had been engaged for several years in the con- struction of the great quays and harbour walls and docks at the latter place by the pneumatic process. It would be as well to take this oppor- tunity of dispelling the notion which has somehow gained credence, that the foreign workmen mostly North Italians, with a sprinkling of French, Belgians, Austrians, and Germans— were better able to work in and resist the high atmospheric pressures necessary to this kind of work, than the British workmen. That this is not so is proved by the fact that large numbers of the Forth Bridge men — carpenters, fitters, and ordinary labourers — I were frequently employed below, and many of | their number for the first time, when the pressure ' was already considerable, without experiencing any ^ great inconvenience or harm. It is, in the first ] instance, a matter of habit, although it certainly | requires good health, freedom from pulmonaiy or castric weakness, and abstemiousness, or, any rate, moderation in taking strong spirituous liquors. ! Some of the most experienced hands oi M. Feb. 28 , 1890 .] Coiseau suffered when they had been making too free with the whisky overnight, and a good deal of the disorders that ensued were traceable to the same source ; though, on the other hand, wet feet, or incautious and sudden change from a heated atmosphere into a cold and biting east wind, in- sufficiency of clothing, and want of proper nourish- ment, had their influence in causing illness among the workers. Although these six caissons were founded at depths varying from 63 ft. to 89 ft. below high water, with an average time of seventy- eight days for each, not one death can be properly and justly attributed to working in high pressure. Two men died during the time, but both were already consumptive when they commenced working here, and the rigour of a Scotch winter had, at any rate, as much to do with their deatli as the air pressure. Another man became insane, and had to be sent back to his own country. The principal bad effect produced by the air pres- ENGINEERING. Various researches were made by members of the medical staff in the endeavour to give relief or I obtain a cure, but, so far, not with any degree of success. Sinking of the Caissons. The operation of sinking a caisson through mud, silt, or clay differs somewhat from that pursued in sinking through solid rock, at any rate in the mode of attack. In the Queensferry caissons the first thing to be done was to fix pipes in the air-shaft, one for the admission of water, the other for the removal of mud diluted with water. As this process of ejecting matter will be described further on, it need only be mentioned that by degrees the shaft first, and next a space underneath it in the air-chamber, was cleared, and access had to the latter. As soon as the ejector pipes described above could be reached, flexible hose was attached to them, and a larger 2 39 _ lost here from this cause, which in other works had proved fatal to so many. In using the ejectors the following mode of working was employed. (See Fig. 48.) A sort of sump or hollow in the ground was formed, and into this the water from an overhead tank was allowed to flow in any quantity desired, and mixed with the more solid material exca- vated. A man who held the end of the flexible hose attached to the ejector manipulated the same in such a manner that a certain amount of the air inside the chamber was allowed to enter into the ejector pipe with the mixture in the sump. This air in escaping carried with it a certain amount of liquid, and forced it out at one of the openings in the caissons above water level. The operation is shown in the cut figured here. It is somewhat puzzling at first to understand why the air pressure, which is only j ust equal, or only slightly exceeding that which is due to the head of water outside, should lift and Fig. 47. Section of tilted caisson after completion. Fig. 48. Sinking the queensferry caissons. Fiij J/0. Fig. 50. sure appears to be that of severe pains in the joints and muscles of the arms and legs. As these have been, in most cases, traced to hard work and con- sequent copious perspiration, and also to too long a | stay under pressure, it has been suggested as a pro- j bable cause that small globules of air make their way through the skin, or between the skins, where they remain, and on the workman returning to ordinary j atmospheric pressure, expand, and thereby cause the ] most agonising pains in the joints, the elbows, shoulders, knee-caps, and other places. In seeming confirmation of this, the sufferers got instant relief j on returning into the high pressure. Thus it ' happened that many of those afflicted with this disorder spent the greater part of Saturday after- noon and Sunday under air pressure, and only came out when absolutely obliged to do so. number of men employed to clear the caisson of the semi-fluid mud. Great care was required during this early stage of the work, and the weight J of the caisson regulated to a nicety, for there was nothing but its buoyancy to prevent it from suddenly descending and smothering the men below. At low ! water was naturally the most dangerous time, there being the least displacement in action then, while j the weight was greatest, and moreover the cutting edge resting upon a treacherous ground. The men were generally withdrawn at this time, and the air pressure diminished, allowing the caisson to descend as far as it would go. On one of these occasions the caisson suddenly descended some 7 ft. , and not only the air-chamber but part of the ascending shaft became filled again with mud and silt. It is satis- ! factory to be able to say that not a single life was discharge a quantity of semi-solid material at a, level above the water; the explanation will, however, be found in the fact that the velocity of the air due to this pressure is very much higher than that of water flowing under the same head, and that it carried mechanically along with it as much of the fluid as it could convey. Of course the man who manipulated the end of the hose in the sump had to feel his way into the solution of this problem, and had to vary the quantities or proportions of air and liquid according to the requirements of the moment. Outside the caisson the flow from this ejector was not continuous, but in gulps, like that from a single plunger pump, now in a large mass, now in a thin stream, and at times nothing at all. As soon as all the soft material had been re- moved, and a bed of stiffer clay reached, the ejector 240 ENGINEERING. could be used only for removing the superfluous water, and picks and heavy spades had to be resorted to and the material charged into the buckets and hoisted out by the locks. Lines of narrow-gauge rail- way were laid down to run small bogies, on which the skips were carried in all directions within the chamber. Presently the hard boulder clay was reached, which was nearly dry, and which proved tougher and harder than anything the existing tools could work in. Various means were tried, and even blasting by powder or dynamite resorted to, but with little result. The rate of progress became exceedingly slow, and the men’s energies became quite exhausted. Here Mr. Arrol’s inge- nuity fortunately came to the rescue, and he devised a most simple, yet a most efficient, tool to grapple with this difficulty — namely, a hydraulic spade shown in Figs. 49 and 50. It consisted in the main of a ram, to which a spade is attached, the ram fitting into a cylinder, which represents the handle of the spade. On the top of the cylinder was fitted a head-piece, which could be set against a piece of batten or any other convenient object. The ceiling of the air-chamber furnished the resist- ance, and the projecting rivet heads were useful in preventing side slip of the head-piece. The spade was lifted by two men, a third attending to the fixing of the head and the turning of the cock admitting water pressure. This was of the ordinary amount, namely, 1000 lb. per square inch, less the amount of air pressure inside the caisson. The spade was set on the ground, the pressure turned on, and as soon as the head-piece had been firmly set against the ceiling the full pressure was given, and the spade forced down into the clay. The water was then exhausted and the spade brought forward, thereby detaching a slab of clay from 16 in. to 18 in. deep, and from 2 in. to 4 in. thick. The spade was then set up again, and the clay thus cut away in long ridges all over the area. Many of these slabs of clay had to be cut to allow them to be charged into the skips. Any boulders too large to pass through the air-shaft were either drilled and blasted, or left in the chamber to be hereafter incorporated with the concrete filling. The water discharged by the spades had to be collected in a sump and discharged through an ejector. In digging or undercutting the edge of the cais- son all round, the spades had to be worked at an angle varying from 30 deg. to 60 deg., the rivet- heads coming in usefully here to provide a good hold for the headpiece of the spade. In undercutting round the sides, portions were left standing to carry the weight of the caisson while excavation was still going on, and these por- tions were by degrees removed until the bearing surface became too small to sustain the weight, and the caisson settled down into them. In proportion as the caisson descended, more weight was added on the top ; but this was also required to be done with care, for fear of displacements taking place. After entering into the hard clay, the caisson edge was nearly sealed by the pressure of the water upon the clay outside, and instead of the pressure of air corresponding to the head of water outside, a few pounds sufficed to keep the caisson dry. Thus, in the case of the Queensferry north-east caisson, founded at 89 ft. below high water, the out- side head is equal to fully 42 lb. of air pressure inside, but it was actually worked and finished with a pressure of from 15 11). to 18 lb. per square inch, after once the hard clay had been entered. This made it, of course, much easier for the men to work in, apart from a considerable saving of wear and tear of the machinery. It will be readily understood that it was of para- mount importance that the caissons, when sunk to their final depth, should be in the correct positions laid down for them ; yet it is equally easy to under- stand that in sinking such a mass it would not take a great deal to cause a displacement in one way or other, since there is nothing to hold it in its proper centre. The position of each cai son was therefore checked nearly every day, and if it deviated in any way from its right course, steps were at once taken to remedy this. To do this it was only necessary to undercut the caisson edge on the side to which it had moved, and to gradually tilt it to a small degree in the direction of that side. When this had been done the caisson was sunk further down for a distance with this tilt on it, and was then righted by undercutting on the high side. This was repeated until the centre of the caisson had got back to its [Feb. 28, 1890. proper position. The slight upward taper in the cylindrical portion of the caisson added some little help in that direction, and the writer thinks that a little more taper than that given to the Forth Bridge caissons would be found very advantageous in future works of this kind. Another plan is to set up inside the air-chamber and against the top of the sloping plates of the shoe, a number of strong in the direction in which it is intended that it should go. This should also be done at high tide, when the buoyancy of the caisson is largest. As in all things, so here, prevention is better than cure, and it is best to keep a sharp eye upon the workmen in the chamber, to insist that the edge be undercut on the outside to the extent of 6 in. to 8 in. all round before it is allowed to descend, and to have the posi- Crane, fbr d is chi Bud Fig. 51. Section of caissons with air-locks and working chamber. TABLE No. V. — Progress of Work with Caissons and Piers. — South-West. South-East. North-East. North-West. Launched and towed to berth ... May 26, 1884 Aug. 24, 1884 Nov. 24, 1884 Dec. 3, 1884. Commenced sinking Sept. 1, 1884 Nov. 24, 1884 Jan. 28, 1885 Submerged Jan. 1, 1885. Floated again Oct. 19, 1885 Nov. 25, 1885 Level of cutting edge at com- mencement below high water . 33 ft. 33 ft. 37 ft. 52 ft. Tn final position ... Dec. C , 1884 Feb. 4, 1885 April 10, 1885 Feb. 4, 1886 Level of cutting edge below high water 71 ft. 73 ft. 89 ft. 85 ft. Commenced concreting of air chamber ... Dec. S , 1884 Feb. 7, 1885 April 14, 1885 Feb. 5, 1886 Finished concreting of air chamber Dec. 17, 1884 Feb. 18, 1885 April 25, 1885 Feb. 10, 1886 Ct mcrete up to granite level Feb., 1885 April, 1885 June, 1885 March, 1886 Pier completed July, 1885 Sept., 1885 Sept., 1885 June, 1886 timber struts at an angle to the perpendicular, and well secured against some timber or stone in the solid ground. This should be done previous to the caisson being allowed to descend. When it does so all these struts have a tendency in descending to become longer and to force thereby the caisson over tion checked as frequently as possible, in order to find out a movement to any side at once, and not allow it to become too great to be remedied. In working on a sloping face, whether of rock, silt, or clay, it is good practice to keep the caisson tilted very slightly to the lower side, which has the effect of fore- FLOATING OUT CAISSON FOR QUEENSFERRY PIER, MARCH 26 1884 2\2 ENGINEERING. [Feb. 28, 1890. mud and silt had been removed previous to its being raised ; hence the greater depth at commence- ment of sinking. When working in the hard boulder clay, for twenty-four hours with the full complement of twenty-seven men below in the air-chamber, and with four hydraulic spades going, a bucket was sent up every five minutes, or 288 buckets in the twenty - TABLE No. VI.- launching the timber shoe was 27 ft. 274 ft. 40 ft. 52 ft. 48 ft. 524 ft. 75 ft. 62 ft. 71 ft. 73 ft. 89 ft. 85 ft. 23 ft. 204 ft. 14 ft. 23 ft. 6372 6651 6827 6271 When floated across from the Queensferry jetty the caissons were at once attached to the mooring chains provided for them, and, in addition, had give the caisson a solid base to rest on. Nature and Depth of Strata through which Caissons were All below f Level of 1 ' lud "“ft •• , 7 Hit'll < 5 5 clay and boulder clay Water 1l ” cutting edge at finish kDepth through hard ground ... Total excavation in cubic yards ... four hours, which was equal to a little over 5 cubic yards per man per twelve-hour shift. The total amount of excavation over the full area was equal to 145 cubic yards for each foot in depth. Even this rate of progress was frequently exceeded under favourable circumstances, but was of course largely above the average daily work. The different strata through which the caissons passed, were — water, deposited mud, stiff mud, silt, a layer of pebbles and stones, soft clay and boulder clay. In the last strata were found large rocks well rounded off, of granite, limestone, free- stone and other kinds, many of which showed upon their flat faces, the distinct grooving or scoring due to glacier action. Amethysts and pebbles of all sorts, and large round boulders of conglomerate were also found, but no traces of fossils or of animal life, not even a live toad. The excavation finished, the chamber was cleared of all material used during sinking, and preparations made for filling the whole space with concrete. The bottom ends of the air-shafts were closed by plates previously prepared, to which was attached a hinged door opening downwards. The large air locks were then removed from the tops of the shafts, and small tubes 18 in. in diameter fixed inside and carried up some distance to a platform, where the concrete mixer was stationed. A valve or small air- lock was set on the toji of the 18 in. tube. Outside the latter was of course ordinary atmospheric pressure. Similar arrangements were made for the other small shafts placed in the caissons from the beginning. Concrete was now deposited close to the lock, a signal was given, and the lower door in the air-chamber was hermetically sealed, the air let out of the shaft and the upper valve opened. Concrete was shovelled in till the pipe was nearly filled, the door then closed, and a signal given. Those below then opened a small valve to let com- pressed air into the shaft, the lower hinged door was opened and the mass of concrete fell on the floor and was taken up into barrows and carried all round the edge. There it was firmly rammed in and pounded with wooden rammers into every hole and corner, and thus gradually laid up the sloping face two Inchgarvie caissons, a strong pressors were worked at somewhat greater speed fi xec j i n each of the two places to increase the pressure, and the chamber was soon which would come to lie immediately upon the two , clear again. The firing was done as often as piers (Figs. 30 and 31), built up of concrete bags on ] possible at the end of a shift to cause the least the opposite side to where the caisson was likely 1 delay and loss of time. The firing of the blocks of to first touch the rock. The timber frame was rock upon which the caisson rested, was generally brought down flush with the cutting edge, so as to done at low water, the caisson crushing into the debris with irresistible force. A number of men then descended and cleared away the de'bris, which Sunk. was sent up in the skips, passed through the lock, and discharged over the side as described in the case of the Queensferry jiiers. Another lot of men cleared away some of the sandbags and cut under the edge into the concrete piers, while the remainder, were at once set to to drill fresh holes where isolated points remained standing. As mentioned in connection with the Queens- ferry caissons, careful examination was daily made, or evenoftener, as to the position of the centre of the stout wire ropes passed round them, the other ends caisson, and if it had shifted it was at once tilted of which were passed round the north piers already | to one side and speedily brought back to its place 1 5 'N V ^ ^ V i Gi an He / ’/er is ft ^ \ STRUTS AND WEDGES IN AIR-CHAMBER built. Careful watch was kept day and night to guard against accidents, and further loading with concrete was at once proceeded with, while the remaining machinery, air-locks, Ac., were placed inside, and the flexible tubes for the supply of compressed air and water, attached. As soon as the caisson com- menced to touch ground at low water, the loading was suspended, and a descent made into the air- chamber to examine the points where the cutting edge was touching, and to put in any further support that might be considered advisable. In this way two piers of sandbags were built up to the ceiling as an additional safeguard against slipping, and these piers were near the centre of the caisson, but rather on the side of the concrete piers. Work was now commenced in short shifts, both before and after low water, in order to remove as much rock as possible under the cutting edge on the high side, as it was deemed advisable that at least one- fourth to one-fifth of the circumference should rest on the solid rock and in a sort of chase before the of the shoe. Against the ceiling" also the concrete F ai ® son was loaded to such an extent as to prevent was carefully rammed, and thus by degrees the whole floating even at high water. It was thus fully chamber built in, leaving only passages between the a , ^^fht . after the caisson was moored in its places where the concrete was passed down. These P. ace ' jefore was allowed to settle down, and to also were by degrees filled up, and the last of the rise 110 more - Excavation then commenced in concrete had to be passed through the men’s lock and down the air-shaft in buckets until this also had to be filled. The air pressure was of course kept on during all this time to keep the water from washing in and out. Finally, all the shafts were filled up, and cement grout was run into these until it stood up to the level of the water outside, the pressure being kept on these shafts for about thirty-six hours longer. The remaining space of the caisson above the air- chamber was now filled up with concrete to the low- water level at which the granite courses commenced. The concrete in the air-chamber was of the follow- ing proportions : Round the cutting edge and under the shoe, and for about 4 ft. all round within this space, 27 cubic feet of stone, 61 cubic feet of cement, and 6| cubic feet of sand. Inside this space and inside the caisson above the air-chamber, the propor- tions were 27 cubic feet of stone to 44 cubic feet of cement, and 41 cubic feet of sand. The grout used was pure cement and water. Inchgarvie Caissons. With regard to the Inchgarvie south caissons, the mode of working varied somewhat owing to the fired by an electric battery simultaneously, nature of the rock bottom. The preparations which ■ wooden trap-door was provided to close the both earnest, although the rate of progress was slow at first owing to the comparatively small area which j could then be attacked. The mode of working was very simple. A number of holes were drilled at first by ordinary hand jumpers, one man holding the drill and two striking ; later on, by the pneumatic rock drills driven by compressed air at 70 lb. to the square inch. The holes were drilled under, and some 12 in. beyond or outside the cutting edge, and when carried to their full depth were plugged and others proceeded with, until a sufficient number were done. They were then charged with explosive and the charges fired. In these caissons also, blocks of rock were left standing for cutting edge to rest upon, while between them the rock was removed. The rock-drills were also worked within the area of the chamber so far as the bottom was uncovered by water, and where possible ordinary quarrying with crowbars and heavy hammers was carried on. At first the charges were fired by time-fuzes, but, as the number of holes increased, insulated wires were laid to the boreholes, the ends being gathered together and brought up into the air-shaft, where they were A Pier with permanent caisson. In these caissons, of course, the air pressure became the j greater with every descent; for the water had full 1 access to them at all times. On the other hand, the atmosphere was singularly sweet and fresh, as a large quantity of air was forced past the cutting edge, and ascended in a mass of bubbles by the side of the caisson, looking exactly as if it were boiling all round. The effect of this is shown on Plate YI. , where the south-east caisson is nearly down to its final depth, while the south-west is floating still. The caissons were lighted by arc lamps and incandescent lamps, and so large was the air-chamber that it required five or six lights of * ^ _ I -ap-cloor was provided to close the bottom J 2000 candle-power each, to give a tolerable light ; had been made for the reception of these caissons, [ of the air-shaft and prevent the fumes from passing | it took much care and trouble to protect the lamps and the levelling by means of concrete piers and 1 upwards, all the men being withdrawn during that ^ and cables against the effects of blasting, sandbags, has already been described. Previous to time. After the charges were fired the air com- 1 The rock-drills were of an ordinary type, mounted Feb. 28, 1890.] ENGINE ERIN G. 24: on three-legged stools or stands for vertical or steep-inclined drilling, and on timber frames for horizontal or slightly-inclined working. The ar- good working order, the,) drilled a large number of holes in the course of a day. In these two caissons the tendency to go down rangement through which they were made to dis- hill manifested itself strongly, and powerful timber Iy.54 TABLE No. VII. — Progress of Work on Inchgarvie Caissons. South-East Caisson. South-West Caisson. Launched March 30, 1885 May 29, 1885 Towed to its berth, Inchgarvie May 15, 1885 •July 16, 1885 Touched ground at low water May 25, 1885 .July 29, 1885 First descent to chamber May 26, 1885 August 5, 18S5 Commencement of sinking May 27, 1885 August 6, 1885 Level below high water at commencement ... 51 ft. 64 ft. In final position August 15, 1885 October 1, 1885 Level of same below high water 63 ft. 9 in. 72 ft. 1 in. Commenced concreting chamber August 19, 1885 October 2, 1885 Finished concreting chamber ... September 1, 1885 October 10, 1885 Caisson filled to granite level ... September 15, 1885 October 30, 1 885 First granite laid September 19, 1885 October 30, 1885 Pier completed November 20, 1885 February 22, 1886 charge the compressed air by which they were driven into - the general atmosphere, did great ser- vice in keeping the air pure just in the places where most of the men congregated, and when in struts and hardwood wedges covered with steel plates had to be employed to keep the caisson in its position, or to force it back when it had moved. These were set on prepared faces on the rock, as shown in the sketch, Fig. 52, and their action upon the caisson will be readily understood. The actual blasting of the rock under the cutting edge does not appear to have injured the steel edge in any way ; but large chips of rock lodging between the outside face and the iron plating caused some accident's, which were not, however, of any conse- quence. On several occasions photographs were taken in the air-chamber, some of them requiring an ex- posure of fifteen to twenty minutes ; but they were not very successful, owing to the changes in the atmosphere and the uncertain light of the arc lamps. Whenever the air pressure increased to a slight extent the atmosphere became quite clear and transparent ; then the air would rush out at some point under the caisson edge with a noise like distant thunder, and a great wave of cold water came rushing back. This caused a dense white fog to suddenly rise in the air-chamber, which obscured everything for a few moments and then gradually disappeared again. Through the gaps left in the heaps of sandbags a number of strange visitors used to make their appearance, attracted, no doubt by the glare of the lighted chamber, which at night could be distinctly seen from above — such as salmon, dogfish, octopus, many other fish, crabs, and a large number of lobsters. One of the latter — a large specimen — got very excited in the chase after him, and leaped up nearly the full height of the chamber in his frantic endeavours to escape — finally jumping into an empty skip, whence he was promptly transferred to the boiling-pot. With regard to the working hours of the men employed after the caisson had once settled down on the rock, work was carried on day and night, the only stoppage being from 6 p.m. on Saturday till midnight on Sunday ; but the air compres&ors had to be kept going all the time, and the full pressure of air maintained. Watchmen were also kept constantly on duty in the chamber when work was not carried on. At first the men worked in eight-hour shifts, with eight hours off, later on six-hour shifts with six hours off, and finally, in the higher pressures, with four-hour shifts and eight hours off. The total excavation for the four piers on Tnch- garvie, and the four piers on Queensferry, and the four piers on Fife, are given in a tabular statement further down, together with other quantities. The total of the wages paid by the sub-contractors to their employes, including managers’, engineers’, and time-keepers’ salaries, amounted to 11. 15s. per cubic yard of rock excavated in the Inchgarvie south-east caisson, and to 21. per cubic yard in the Inchgarvie south-west pier. Neither of the Inchgarvie caissons was carried down to the full depth contemplated (see Fig. 53), as it was found that only a very small area remained to be filled up when the caissons had got to the depth where they were left. These places were carefully levelled and stepped, and iron plates were litted in to close the gap between the caisson edge and the rock, and the spaces were then carefully built up with concrete bags and the whole grouted with cement at slack water. Upon this foundation con- creting was commenced, and the whole chamber gradually filled with concrete in the manner de- scribed for the Queensferry caissons. I 11 Table No. VII. are a few data of interest in connection with these two caissons. The Circular Granite Piers. The foundations below low-water level of ten out of the twelve circular piers, vary both in size and considerably in depth, but above that level they are exactly alike. The two exceptions are the two north piers on Fife already described. Their foun- dations start at 7 ft. below high water, and they are only 45 ft. in diameter under the necking course. In all other respects they do not differ from the remaining ten piers. In all these the granite masonry starts at low-water level, or 18 ft. below high-water level, with a diameter of 55 ft. ; rises with a regular straight batter of 1 in. in 1.0 J> in. to a height of 12 ft. 8 in. above high water, where the diameter is 49 ft., and terminates in a necking and a coping course with a somewhat rounded top at exactly 18 ft. above high water. The courses of granite, of which there are nineteen, are rock-faced, while necking and coping are of dressed granite, vary in thickness from 21 in. in the lower to 16 in. in the upper courses, while above these the necking is 19 in. and the coping about 3 ft. 6 in. thickness 244 ENGINEERING. [Feb. 28, 1890. TABLE No. VIII.— CIRCULAR GRANITE PIERS.— TABULAR STATEMENT OF QUANTITIES. All Excavation — Concrete, Rubble, and Brickwork in Cubic Yards. Granite in Cubic Feet. Steel, Iron, and Cast Iron in Tons, Cwts. and Qrs. Piers. Q. — Queensferry. G. — Inchgarvie. F.— Fife. Excava- tion. In Foundations below Low Water. In Circular Pier. Steel. Iron. Cast-Iron Anchor Plates. Concrete. Brick- work. Rubble. Rubble. Granite. Brick- work. Cutting Edge of Caisson, &c. , Plates. Holding-down Bolts. Caissons. Belts. Tons cwts. Tons cwt. qrs. Tons cwt. Tons cwt. Tons cwt. Q. N.E.') r |g u 6827 9601 Nil Nil 2376 13,621 Nil 52 7 9 6 3 399 0 9 9 12 12 Q. N.W. 1 6271 7547 1105 2376 14,543 52 7 9 6 3 454 18 9 9 12 12 Q. S.E. f 6651 7361 Nil 2305 13,237 52 7 9 6 3 338 5 9 9 12 12 Q. S.W. J 6372 7089 9 1 2305 13,237 52 7 9 6 3 340 7 9 9 12 12 G. N.E. S 755 Nil 236 2300 13,237 Nil 9 6 3 24 3 16 14 12 12 G. N.W. ( .S a* 324 Nil 626 608 2300 13,237 9 6 3 38 10 17 1 12 12 G. S.E. [ £ O 1054 5635 Nil 2300 13,237 95 16 9 6 3 334 13 6 12 12 G. S.W.J 831 6576 807 2300 13,237 95 16 9 6 3 360 11 13 6 12 12 F. N.E. b 438 Nil Nil 264 854 6484 Nil 8 12 2 Nil 8 12 12 12 F. N.W. \ .5 P 444 481 494 6842 350 8 12 2 8 14 12 12 F. S.E. f ^ O 1004 836 2300 13,237 Nil 9 6 3 48 2 20 9 12 12 F. S.W.J 823 ” > } 200 2300 13,237 > > 9f 9 6 3 21 17 16 13 12 12 The latter two courses are of Cornish granite, the others of Aberdeen granite, both light grey in colour. The blocks of rock-faced granite have the edges dressed to the batter of the pier, and to horizontal and vertical joints. The courses are alternately headers and stretchers, with a bond of not less than 9 in. The joints are not more than 4 - in. wide, and are pointed from the outside with pure cement. The hearting is principally of flat bedded Arbroath rubble, but a large number of whinstone blocks roughly squared were also built in. In building the pier the rubble masonry closely followed the setting of the granite, and both vertical and horizontal bond was strictly observed. Between the concrete in the foundation and the rubble masonry in the piers bond was also established by large blocks of whinstone squared to obtain proper bedding. (See Figs. 54 and 55.) At this point a wrought-iron belt 56 ft. 6 in. in diameter, 18 in. in depth and f in. thick, made in sections and rivetted together, was placed and built in. A second belt of similar strength, but only 43 ft. in diameter, was built in about 2 ft. below high water, and a third belt of double strength, or 11 in. thick and 39 ft. in diameter, was built in just behind the coping course. All these are shown in Fig. 54. When the level 7 ft. below high water was reached a temporary timber stage was erected and carried to the level of the underside of the fixed bedplate about 17 ft. 6 in. above high water. Upon this a templet of the bedplates made of light angles and 4 -in. plate in four sections bolted together, which had all the holes for the holding-down bolts in it, was laid, correctly centred and screwed down. The bolts with anchor plates supported by nuts were then carefully set up and built into the rubble masonry, a space of a few inches being left round each bolt to admit of subsequent adjustment. This is very distinctly seen in Plate VII. — Inchgarvie north-east pier. The building of the pier was now continued, the position of templet and holding-down bolts being frequently checked to insure correctness. From the plan it will be seen that the coping course consists of alternate headers and stretchers. The top or crown of the pier is slightly spherical, and is built up of blocks of dressed Aberdeen granite from 17 in. to 18 in. in thickness. The blocks fitting into and adjoining the coping course were all cut to wooden templets sent, the remainder being arranged in straight courses. The blocks pro- ject from 6 in. to 12 in. under the bedplate, a recess being cut out to receive the latter. The remaining space under the bedplate is made up with Arbroath rubble masonry, and in one case with a tolerably thick layer of Staffordshire blue bricks built in cement. The mortar used in building the piers was through- out of one part cement and two parts of sand, and was mixed in a pugmill close by. At first hand cranes only were used in the building, but steam cranes were substituted as being more handy and expeditious. Both granite blocks and rubble were handled and set by means of pointed chain-clips, holes being picked for the purpose. The holding-down bolts in each pier were forty- eight in number, in four rows of twelve each. They are set at 2 ft. 9 in. and 7 ft. respectively to each side of the centre line, and are longitudinally about 3 ft. apart. Owing to the inward set of the bottom members in cantilevers, rather more than half of the bolts are set in a line parallel to the centre line of the bridge, the remainder following the deviation of the bottom member. In order to bring the largest possible mass of masonry into play, the four centre-bolts of each outside row are bent outwards, as shown in Fig. 54, and to prevent any tearing action upon the masonry which would be produced by the bolts being drawn tight at top, cast-iron shoes are inserted at the point of kinking, and these are held together by a pair of angle-bars to each pair of bolts. (Figs. 56, 57, 58, and 59.) The holding-down bolts are of a special steel. They are 2b in. in diameter, with an enlargement to 3 in. at both ends, where a screw thread is cut upon them. They are about 25 ft. long. The anchor plates are 2 ft. square with a long boss, stiffened by four diagonal ribs, and are held by an ordinary nut. The bolts received several coats of tar before being built in. When the masonry had been carried to within about 8 ft. of the top the templet had to be re- moved to allow the rubble to be placed in position, but it was replaced from time to time, and the position of the bolts frequently checked. As the heads of these bolts fitted in the lower bedplate without any play whatever, it was necessary that their position should be absolutely correct. When the masonry had got up close to the under side of the bedplate the bolts were again set with the greatest care, and the spaces left round them were tilled up with cement grout to within about 4 ft. of the top. Immediately underlying the bedplate, and with a view of making a perfectly level bed for the same, cast-iron blocks, 12 in. square and 4 in. thick, with a hole which only just admitted the head of the bolt, were placed, carefully levelled by instrument and set in cement, the spaces all round and between these being levelled to the thickness of 1 in. with cement. In addition to the round hole in each block, a slot was cut and a taper wedge driven hard into this and against the screw thread. This was done to prevent torsion in the bolts when the large upper nuts required to be drawn tight. On the bed thus prepared the lower bedplate was laid in the manner hereafter de- scribed. The heads of the holding-down bolts, as well as square washers, nuts, Ac. , are shown further on in connection with the bedplates. Raising of the Approach Viaduct Girders and Underbuilding of the Piers. The height to which the piers of the approach viaducts had to be carried was 130 ft. 6 in. above high water, and the question how best to deal with both the erection of the girders and the building of the piers was ultimately settled by deciding to put the girders together at any convenient level, and make the lifting of these and the building of the masonry a simultaneous operation. The fifteen spans of 168 ft. each, of a total weight of slightly over 3000 tons, or, roughly, 200 tons per sjian, were built under a sub-contract by Messrs. P. and W. McLellan, of Glasgow, the contract including their being put together and rivetted up on the staging provided at the Forth Bridge. The girders are of the ordinary double-lattice girder type, consisting of two parallel girders at 16 ft. centres, having trough-shaped top and bottom booms and side bracings consisting of inter- secting diagonal struts and ties. The trains run on the top, the troughs of the two outside rails forming the top booms of the girders. Each span is divided into eight bays of 21 ft. each, which is also the height of the girders, and at the inter- section of struts and ties a vertical support is carried upwards to the top boom. A cross-bearer occurs every 7 ft., or three to each bay, and carries not only the two troughs for the inside rails, but also projects beyond the two outside troughs for a dis- tance sufficient to form a 4-ft. path on each side, and to support the brackets of the wind fence. The floor is made up of buckle plates. The bottom booms of the girders are braced laterally by lattice girders intersecting at centre, and there are also vertical cross-bracings of double angles at suitable distances. Two spans are made continuous, and expansion joints are provided over every second pier. The ends of all the girders rest on sliding bedplates, no rollers being used. The details of these girders call for no special remark. They were originally intended to be built of wrought iron, but, in view of the cheapness and excellent quality of steel, the latter material was ultimately adopted. Various circumstances combined to fix the height of the staging on which these girders were put together. On the Fife shore the high grdund upon which the cantilever end pier and piers 10 and 11 were founded necessitated the putting up of staging to a height of 41 ft. above high water ; the four piers 10 to 13 having by September 30, 1883, been brought up to 37 ft. above high water. On this staging the girders were erected and rivetted up, the last length next to the north canti- lever end pier and nearly half the length of the span between pier 13 and the abutment being left out, however, for the time being. The cantilever end pier had been built up to a considerable height, and between pier 13 and the abutment a public road passed at a considerable height above the then level of the staging. As the mode of raising the girders will be more fully described in connection with the south approach viaduct, it will be sufficient to state here that, in order to raise the end of the girders nearest the cantilever end pier, a set of strong columns were built up and lengthened by degrees as the lifting proceeded ; and upon these the hydraulic cylinders were placed. The mode of raising was similar to that employed for the large platforms of the central towers, and fully described there. Upon piers 10, 11, 12, and 13 the lifting proceeded in the usual way, but, not far from the abutment, a set of columns similar to those at the Feb. 23, 1890 .] ENGINEERING. 245 TABLE No. IX.— Viaduct ITeks and Cantilever End Piers.— Tabular Statement of Quantities. All Figures for Concrete and Rubble in Cubic Yards — for Granite in Cubic Feet. Foundations. Granite Masonry Piers. Concrete. Rubble. Concrete. Rubble. Granite. Freestone Bond Courses. Soxith Viaduct. Pier No. 1 246 nil 42 314 5526 not stated „ 2 176 nil 322 318 5591 1793 ,, 3 151 nil 413 607 10002 3425 ,, 4 73 nil 540 607 10002 3392 ,, 5 72 nil 622 607 10002 3513 ,, 6 80 nil 685 607 10002 5912 ,, 7 228 nil 936 607 10002 5993 ,, 8 320 nil 973 607 10002 5946 „ 9 706 nil 973 607 10002 5987 South Cantilever End Pier 2167 295 1753 3420 43984 39078 162 of blue brick North Viaduct. North Cantilever End Pier 205 nil 774 2320 32944 17305 37 of blue brick Pier No. 10 69 nil 90 598 11610 not stated „ 11 52 nil 130 611 11814 1954 „ 12 273 nil 304 508 11756 „ 13 340 nil 419 610 11789 1019 Table No. X. — Shovnng Quantities of Masonry Piers, Arches, and Abutments certified for up to November 30, 1SS9. — Cubic Yards. Cubic Feet. Concrete 64,315 Rubble 48,356 Rock-faced granite . . . 494,642 Dressed granite 140,756 Bond courses ... 105,180 Totals 112,671 740,578 Grand total, 140, 100 cubic yards. Note . — The quantities of masonry, &c., for abutments and arches are not given in tho detail statement above, but they are included in the totals here stated. Some 7500 cubic feet of granite for completion of the cantilever end piers have to be added. VIII. — were also stowed the hardwood packings and other necessaries for the lifting work. All these things put a great deal of extra weight on the girders, but as neither buckle-plates nor wind- fence had been put on as yet, the weight did not greatly exceed that of the finished girders. The mode of procedure was as follows: — Hard- wood packing in of slabs varying thickness, from other end were used. When the girders had been raised to a point above the cantilever pier and the abutment (as far as these had by then been built) the two ends were joined on, and the completed girders raised up to their final position. The first lift of these girders was made about the middle of October, 1885, to level 42 ft. above high water, and the last lift to level 130 ft. 6 in. above high water on February 15, 1887. The connections of the permanent way on this viaduct with that on the cantilever at one end and with that on the masonry arches at the other end are made by means of expansion joints, identical with those used at the fixed ends of the Fife and Queensferry central connecting girders, and fully described in connection with the latter. On the Queensferry shore, owing to the rising ground between pier 3 and the south abutment, the girders had also to be built at different levels, and were only joined when the various portions had arrived at the same level. The seven spans from pier 3 to south cantilever end pier were all built on staging erected between the piers, and rising to a few feet above the masonry, in order to allow the lifting rams and lifting girders to be placed between piers and viaduct girders. Piers 3 to 5 had been brought up to level 18 ft. above high water early in January, 1884, pier 6 in March, 1884, pier 7 in October, 1884, pier 8 and cantilever pier in February, 1885, and pier 9 in June, 1885. The delays which occurred were due to difficulties and to a larger amount of woi'k in connec- tion with the construction of the cofferdams and the building of foundations and lower portions of those piers; but so soon as any of them were completed, the staging between was built, and a start made with the erection and rivetting of the viaduct girders. Thus it was possible to have everything ready and to commence lifting early in the month of May, 1880. Piers 2 and 1 had in the mean time had their foundations laid and their masonry raised to about 43 ft. above high water, while the abutment on top of the hill was raised to 115 feet above high water. For the purpose of raising the viaduct a box girder of great strength, about 22 in. deep, 2 ft. 0 in. wide, and some 24 ft. in length, was placed directly under the girder end-posts— that is, along the centre of the piers. During the raising of the girders temporary connections had been made be- tween girders at those places where expansion and contraction could take place. Immediately under each main girder a hydraulic ram, 14 in. in diameter and 16 in. stroke, was inserted in the box girder, and was made a fixture in it. There was thus a length of girder of about 3 ft. outside each cylinder for packing. All the cylinders were connected with force-pumps, which could pioduce a pressure of 35 cwt. per square inch, the pumps being placed within the bottom booms of the viaduct girders, which were completely decked over and used as a road, being fenced on each side, and having two narrow-gauge lines laid down on it, during the time of lifting. Round each pier a timber platform was suspended from the girders, so arranged that its planking could be brought up close to the masonry as the piers diminished in size with the ascent. On this platform — which is clearly shown in Plate 1 in. up to 12 in., was placed under the girders in two or three places, and by means of long wedges, one worked from each side, every lift was closely followed up to prevent sudden drops, should the hydraulic presses give way. When a lift of 1 ft. had thus been made, the girder was packed and the ram was fleeted — that is, drawn back into the cylinder — and a hardwood block with a strong steel plate on top was underlaid and a further lift made. At first it was attempted to raise the whole mass of over 1400 tons at once on all points, but this was not found to work very well, and it was then arranged to work 3 in. at the time only, and lift on each pier in succession. No accumulator was used, but the pumps were just kept going until the girders were up. As a rule the lifts were of 3 ft. 6 in. at the time for two courses of masonry, but at times a foot more or so was done, according to requirements. With the last lift on each occasion the packing was so arranged as to occupy the least room upon the masonry last done, and the masons then at once proceeded to set the granite facing and build the rubble backing in every place that they could get at, taking good care to leave the work so as to make sufficient bond with the remainder. After allowing forty-eight hours for the setting of the new work, the weight of the girders was shifted on to packings laid on the new work, and the remain- ing portions of the two or three courses, as the case might be, were then built in. After due allowance for the setting of this work also — another forty-eight hours generally — a fresh lift was made. 246 ENGINEERING. [Feu. 28, 1890. All materials for building were raised to the girder level by means of two hoists stationed at either end, and the materials so raised were run on trollies by boys or drawn uy Shetland ponies to the places clusively, as it was feared that the concrete could not set sufficiently hard in the time allowed between the lifts, while the Arbroath rubble masonry set firmly and solidly in about thirty hours. removed from under it, and was transferred a span further forward. After the piers were in position the temporary connections at the joints where provision had been BENDING PRESS FOR PLATES AND MACHINE FOR PLANING ENDS OF CURVED PLATES. where they were required. Thus granite blocks, Arbroath rubble, and mortar, were all prepared on the jetty below and lifted up. To assist the masons in their work of laying granite and rubble an overhead traveller was placed to each side of every pier. All these travellers were worked by friction gear and clutches, both for hoisting and lowering, or for travelling, an endless wire rope being run along the girders from end to end, driven by the same engines which drove the pumps during lifting. When the seven spans had thus been raised to 47 ft. above high water, the next two spans from pier 3 to pier 1 —which in the meantime had been erected on staging passing over the Edinburgh-road — were joined on, and the further lifting proceeded with in the same manner as before. The last span from abutment to pier 1 had meanwhile been erected on staging at level 119 ft. above high water, and was joined on when the other girders reached that level, the complete viaduct being then raised through the remaining 11 ft. The first lift at South Queensferry was made from level 23 ft. above high water in May, 1886. Level 47 ft. above high water was reached August 10, 1886. Level 91 ft. above high water was reached Feb- ruary 15, 1887. Level 119 ft. above high water was reached June 14, 1887. Level 130 ft. 6 in. or top was reached August 7, 1887. No mishap of any kind occurred in the course of this work, and in no case did the granite facing or rubble backing show the least sign of giving way during the underbuilding of the piers under this considerable load. After the girders had readied the tops of the piers the cross girders and hydraulic rams were removed and the bedplates substituted. In all cases the thirteen viaduct piers had the hearting constructed of concrete up to the level at which the girders were built, but from the time lifting was done Arbroath rubble was used ex- Y ery little staging was used in this mode of erect- made for expansion and contraction were removed, ing, most of the timber being used over and over and the remaining buckle-plates on the top and the again, for as soon as a girder was rivetted up and wind-fence on both sides were put on. could carry itself across the span the staging was ; After several coats of paint had been put on the Feb. 28 1 8go 1 ENGINEERING. 247 girders they were left until the time when the per- manent way was required to be laid down. One of the views on Plate VIII. shows the girders at full height. The Steel. With the exception of a few hundred tons of cast-iron washers and anchor-plates in the piers, and about 2000 tons of deadweight consisting of cast-iron bricks laid in asphalt — which are placed in the ends of the two fixed cantilevers terminating in the cantilever end piers — the whole superstruc- ture, from holding-down bolts to the ventilators on the extreme top of the vertical columns, and from the granite arches at one end to those at the other end, is built of steel. The choice of a material for constructing a bridge of novel design, of extraordinary magnitude, and exposed during erection to the effects of powerful atmospheric disturbances, must have been the sub- ject of much anxious thought and reflection to the engineers. But, in whatever way the decision was arrived at, there can be no two opinions that the choice was a happy one. From beginning — and probably a long time before the beginning of this work — to the end, this steel was subjected to every conceivable test, both in a properly scientific result being one single corkscrew shaving, about one yard in length, started from the very moment the drill touched the steel and attached yet by the end to the piece of scrap out of which it was bored. It would not, probably, be straining a fact to assume that this behaviour of the steel under severe tests had a great deal to do with the confidence with which the workmen regarded every portion of the structure, and with their belief that no possible load they could pile on the temporary platforms could by any chance bring about a collapse. It is true that, in the early days of plate-bending, some thick plates broke near the edges in a seemingly mys- terious manner, but the investigations made and the reasons adduced in connection with these frac- tures were sufficiently convincing to allay any feeling of distrust. The Board of Trade stipulations in regard to steel for structures, do not go further than to lay down the rule that the maximum working stress should not exceed one-fourth of the ultimate breaking strain of the steel. No difference is made between the tensile and compressive stresses, nor is any re- gard paid to the differences between stresses due to dead load or live load — alone or in combination — nor to the circumstances arising from changes, occurring frequently or rarely, in the nature of the stresses. The engineers therefore laid down, after consul- Fig. 67. Plan of drill roads. BOTTOM MEMBER ON DRILL ROAD. manner for purposes of research or investigation, tat.ion with the Board of Trade and with their and in an entirely unscientific manner by workmen, ! approval, certain rules in regard to the stresses whose only excuse can be that they did not know 1 admissible under varying circumstances, better. But in all cases the steel stood the test, For tension members the steel was to have an and a more uniform, a more homogeneous, and ultimate resistance of not less than 30 nor more than more satisfactory material could not be wished for. 1 33 tons per square inch, with an elongation in 8 in. To only quote one instance, the writer has in his j of at least 20 per cent. For compression members possession several pieces of scrap from the shearing- 1 a resistance not less than 34 tons nor more than machine, picked up promiscuously and placed under 37 tons per square inch, with 17 per cent, elongation, an ordinary diamond-headed drill about 1 in. in With regard to varying stresses for a load varying diameter. A hole was drilled about f in dee]), and between nil and a maximum, 20 tons per square the machine stopiied while yet the feed was on, the inch of section to be assumed as the ultimate 248 ENGINEERING. [Feb. 28, 1890. TUBE DRILLING MACHINE ON DRILL ROAD. Fig. 73. strength if the change occurs frequently, and 221 tons if occurring rarely. For stresses alternately tensile and compressive, the ultimate stress to be 10 tons if frequent and 15 tons if seldom, one-third of the ultimate strength to be considered the working stress. Rivet-steel to have an ultimate strength of 27 tons per square inch, with 30 per cent, of elongation, and shearing resistance to be from 22 tons to 24 tons per square inch. Cast steel to have an ultimate tensile strength of 30 tons, with 8 to 10 per cent, elongation. For tension members the sectional area of the rivets in the joints to be 1J times the useful section of the boom. For compression members the area of rivets in butt-joints to be half the useful section of the member. The original estimate gave the quantity of steel required for the Cantilever Bridge (not including approach viaduct spans) as 42,000 tons. Of this quantity the Landore Works near Swansea in Soutli Wales, of Messrs. Siemens, supplied 12,000 tons, and the Steel Company of Scotland, from their Feb. 28, 1890.] ENGINEERING. 249 Blochairn and Newton Works near Glasgow, the remaining 30,000 tons. For the alterations made subsequently in the design, and the increase of section in various parts, a further quantity of about 16,000 tons was required, about one-half of which was supplied by the Steel Company of Scotland, and the other half by Dalzell’s Iron and Steel Works at Motherwell, near Glasgow. The steel for the viaduct spans, about 3200 tons, is not included in the figures given above. The Clyde of li in. thickness with the ends of the test-piece closed. As regards the steel supplied by the Steel Company of Scotland, all plates were rolled at the Blochairn Works, and all bars at the Newton Works. Failures of the steel under test were of the rarest occurrence. All steel was manufactured by the Siemens- Martin open-hearth process, and all plates, bars, tees, angles, and other pieces, were cut to length and shape as ordered and thus delivered at the works. engineers previous to being passed into the work- shops. If necessary, full-size drawings were made on the blackened floor of the large drawing loft, and from these all templates were made in wood. The templates were carefully cut to size, all holes drilled in them, and all necessary information and description branded upon the template in clear type. In certain cases, such as bracing bars, which recur several hundred times over, some of the bars themselves were used as templates. For the erec- Fig. 75. Tube drilling machine and travelling crane on drill road. Rivet Company, Glasgow, supplied about 4200 tons of rivets. With regard to tests, one plate out of every fifty, picked out promiscuously, had a sti'ip cut out of it which was planed on all four sides and tested for tensile stress in a 50-ton testing machine. The same proportion was observed in the case of bars. For transverse or bending tests a piece was cut off every plate and every bar, about 2| in. wide, and tested by being bent under the press to a radius About 6 per cent, of the total steel delivered was returned as scrap, or between 3000 tons and 4000 tons. A certain proportion of the steel delivered was used for temporary purposes only, and this will account for the difference between the total quantity delivered and that erected. Drawings. All detail drawings were made at the drawing offices attached to the works and submitted to the t'ion of the superstructure the tracings were trans- ferred to sheets prepared by the ferro-prussiate process, by which the only part of the paper remaining white is that which underlies the full or dotted lines of the tracings. The drawing is, therefore, of white lines upon a deep blue ground. Workshops. Two principal divisions were made in regard to the construction, namely, between the tubular ENGINEERING, 250 [Feb. 28, 1890. members and the latticed girders. The former were done in the upper or No. 2 shed and on the drill-roads adjoining it ; the latter, in the lower or No. 1 shed. Considering that as much of the work as could possibly be done was to be drilled with all parts put together, it will be at once understood that not only did the drilling form a most important part of the work, but also that a great deal of special plant designed for each particular purpose would be required. As a broad rule, therefore, all tubular members were put together and drilled through the various thicknesses at once, the only parts done separately being the portions of beams and diaphragms not in contact with the outer shell. In the lattice-girders the booms were drilled singly, on specially prepared beds, made up of timber blocks ; or, if worth while, on cast-iron frames. The lattice-bars were dialled by other machines. In the building of the tubular members the first work to be done was to bend the plates to the required curve. For this purpose the plates were put into a gas furnace (see Figs. CO and 01), Fig. 74. ) The beams were now bolted with their inner ends to the angle-iron rings of the dia- phragms ; and on the beams again, the inside, and later the outside, plates were fixed by means of ordinary clamps and by draw-washers. The under- side of the tube was also supported by timber blocks built from the ground. The centre of the mandrel was now checked by means of a theodolite, and, if necessary, corrected. All was now ready for drilling, except, perhaps, that all holes in the lap-joints of the plates and those for the circular girders required to be marked. The drilling machine, specially designed for this work, was now brought forward. (Figs. 72, 73, and 75.) It con- 1 sists of a wrought-iron carriage A running on a 1 double line of rails on each side of the tube, and to it are fixed in the centre line of the tube two circular frames C C 1 about 10 ft. apart, and com- pletely embracing the tube with about 6 in. of play all round. Upon the frames are placed five cross-girders D D, so arranged that by means of circular rack and worm B B they can work right round the tube, each girder carrying two spindles spindles were thereby placed at right angles instead of radially. Besides the machines here described there were a number of others, all for special purposes, each of which carried out its appointed work in a most efficient manner. Many different types of hydraulic presses for the shaping of bars or corner plates for the square-ended struts were used, and had con- stantly to be altered as circumstances required. Drilling machines, similar only in respect of the fact that they drilled holes, and that they moved alongside the work which was made a fixture, were in use in the lower or No. 1 shed. (See Fig. 76.) These machines had at times ten boring spindles going at one and the same time, and there were on several of the machines as many as thirteen spindles available for use. These multiple drilling machines are shown in Figs. 77, 78, 79, and 80. Here also an ingenious tool was in operation which cut the 3-in. round holes out of the lower bedplates, and which also cut the larger round holes 7 in. in diameter, and the oblong holes 11 in. by 7 in., with rounded corners (see Fig. 96), out of the heated up to a bright red heat, and then passed into a hydraulic press, where, between two dies or saddles, they received the necessary curvatures. (See Figs. 62 and 63.) The plates were then placed aside in piles, covered with ashes, and gradually cooled down. However carefully this is done, some alteration takes place in the shape of the plates ; and to remedy this the plates, when quite cold, were put into the hydraulic press once more and received a final setting. They were then placed into a planing machine (see Fig. 66), where the two long side edges were planed down to the required dimensions ; while in another machine of simple construction the end edges were dealt w.ith in the same manner. (See Figs. 64 and 65.) They were now ready to be built up into tubes on the drill-roads. (See Fig. 67.) Here a long cylinder, or mandrel with wings attached, was supported on a number of trestles, and round this mandrel the tube was built up, the diaphragms being bolted to the wings of the mandrel. (Figs. 68, 69, 70, and 71.) Meanwhile, the beams had been prepared and drilled with the angles attached by ordinary radial drilling machines in the shop. (See II H, which can run from end to end. On one side of the carriage is placed an engine E E and boiler, and the driving of the spindles is. accomplished by air endless cotton rope. Thus arranged, the ten spindles point radially to the centre of the tube, no matter where placed. This machine was now pushed forward to the tube, timber packings being removed in front and replaced behind as the machine advanced, and drilling was carried on until all holes (about 100 per foot run) in the 8 ft. section were drilled. The machine was then moved forward to the next section. On the side to which the machine was moving new beams and plates were always added, while on the other side they were removed and taken to the stack-yard. Before being removed, however, every plate, every beam, angle, cover or strap was typed with distinguishing letters, which made it possible, at a moment’s notice, to fix its position in the structure. In tubular members other than circular, the side frames in which the cross-girders which carried the boring spindles moved, instead of being circular, were of the same shape as the members them- selves and on flat surfaces, for instance, the upper bedplates. Thismachine consisted of a vertica spindle turned by worm and wheel, and upon this spindle was a saddle in which could move forward and backward a horizontal slide which carried a roller on top, and a cutting tool at bottom. The roller at top moved between two frames, which could be removed at will, and which had the same shape which it was desired the hole below cut by the tool should have. It followed therefore that whatever shape these frames had, the tool was obliged to follow and cut a hole the same shape. By placing the tool at different distances from the revolving centre while leaving the roller at the same distance, the size of the hole could be diminished or increased to any desired scale. A machine for planing the very long plates required in the lattice girders is shown in Figs. 81, 82, and 83. It will be noticed that it has an end saddle and tool as well, thus allowing two edges of the plate to be planed at one time. A further feature of the machine is the use of hydraulic rams for holding down the plate in lieu of the usual screws. Here all the tension members, wind-bracing girders, bedplates, and the top junctions with liar Feb 28, 1890 ] ENGINEERING. 1 sides were put together and drilled, as also a mass of small detail work, and all the temporary girders used in the erection and in the stagings. Outside these workshops and the drill-roads, many acres of ground were taken up with the building up and fitting together of the various girders, of which the single booms had been drilled in No. 1 shed. Thus a great portion of the internal viaduct was put together and a number of bracings which had to be templated in the first instance in situ, were done and multiplied. These portions of the internal (see Fig. 75), some with curved jibs 40 ft. high, were used, and these could move about all over the drill- roads, being shifted from one line of rails to another by means of traversers. Ordinary derrick cranes worked by steam or by hand were also largely used. In the shops, however, most of this work was done by hydraulic cranes of very simple construc- tion, yet eminently adapted for their work. (See Figs. 84 and 85.) In many places they were so dis- posed that material could be lifted and swung round viaduct were erected for one pair only, however, and in the others it was simply repeated. The bottom junctions, or junctions between bottom members, struts and ties and wind-bracings in cantilevers, were laid down and finished on the drill-roads, while those of the top members with struts and ties were laid down and built in the field. For the handling of the plates, beams, and other parts of the tubular members and the skewbacks and bottom junctions, powerful travelling cranes from one to the other so as to traverse the whole length and breadth of the shop. (See Fig. 76.) A large amount of rivetting was done in the yards and the field in the case of such portions of the girders as the booms of the tension members, and later on, whole portions of the rectangular wind- bracing girders, of which then the joints only required rivetting up after they were erected. Much rivetting was also done upon the longi- tudinal beams and the diaphragms in the tubular members. All this rivetting was done by hydraulic machines, and could be finished at an extremely cheap rate. The work in both No. 1 and No. 2 sheds, and on the drill-roads, was carried on day and night, though the number of men was much greater during the day-time. The working hours were from 6 a.m. till 5.15 p.m., and from 5.45 p.m. until 5.45 a.m. for night shift. No deduction was made for meal hours during the night, the full twelve hours being paid for. When necessary the work in the field was also carried on during the night. The total output of work from all these places has amounted to as much as 1800 tons in a month, which is a very large quantity when it is considered through how many hands every piece was required to pass before it could be called finished. Bedplates. The lower or fixed bedplates, in size about 37 ft. long by 17 ft. wide, are built up of five layers of plates, the lowest f in. in thickness, the second lj in., and the third and fourth 1 in., alternately laid longitudinally and transversely, to obtain dis- tribution of fibre in all directions. The fifth layer consists simply of a band, 11 in. wide and 5 in. thick, laid round the edges of the bedplate, partly as a stiffener, partly as a means of retaining the lubricating medium between the lower and upper bedplates. Immediately under the vertical column a recess is formed by cutting out of the two upper 1-in. plates a space varying in form, but in all cases for the purpose of admitting a keyplate of similar form, a portion of which is rivetted to and forms part of the upper bedplate. The bedplate as above described was put together on a carefully-prepared bed in No. 1 shed, clamped and fastened down securely, and a traveller with several boring spindles passed over the whole of the plate, drilling all holes through the various thicknesses at once. All holes were 1§ in. in diameter, and countersunk both top and bottom. The forty-eight holes 3 in. in diameter for the holding-down bolts were drilled in the same place, but by a specially constructed tool described above, and the plate was then taken to pieces and stowed away until wanted. As soon as the granite piers were ready for the reception of the bedplates they were put together at a height of about 4 ft. above the masonry, and supported for the time being on short pieces of bolts, coupled to the foundation bolts by long nuts and in other places by pieces of cast-iron piping of equal length. The rivetting machine was then placed at one end, and the rivetting commenced. (See Figs. 86 and 87.) The machine consisted of two strong box-plate girders, carried on two side- frames moving on wheels, and kept apart vertically a sufficient distance to admit the bedplate, with a rivetting cylinder attached to the upper and another to the lower girder. The cylinders could by screw movement be moved from one end of the girders to the other, and thus commanded the whole width of the bedplate, while for forward or backward movement the side-wheels had to be pinched. The two cylinders were turned on simul- taneously by one valve. The cylinders were 12 in. in diameter, and the water pressure 1000 lb. per square inch. The pressure upon the rivet and the plates was, therefore, about 40 tons from each cylinder. The rivets had a countersunk head at one end, and flat snaps were used on both cylin- ders. The rivets were heated in an ordinary brick furnace placed on the pier, and brought to a full yellow heat. There were 3778 rivets in each of these bedplates, which gives for the area of 654 square feet about six rivets per square foot. As soon as the machine had moved away a yard or so from the end of the plate, chippers were set to work to pare down the projecting piece on each rivet-head on the under side of the bedplate, in order to have this perfectly even and flush. After the men got into the way of properly using the rivetting machine, these bedplates were rivetted up in twenty-eight hours, or 135 rivets struck per hour, which is very creditable work, con- sidering the size of the rivets and that so much shifting of the machine and of the supports for the bedplate had to be done. After all the rivet-heads had been chipped, the bedplate was lowered into its place by hydraulic rams. Two thicknesses of canvas, one laid in the length, the other in the breadth of the plate, both being well soaked in and painted over with red lead, were interposed between the cement bed described above (see granite piers) and the plate to 252 engineering. [Feb. 28, 1890. n A n mu c5 ® Eg ® x* '-I 13 r-t S «4-l Ct rirrj Cfi S to „ O £ | i> I ■*= 5 .s * w s S C CO 5 'S -43 Feb. 28, 1890.] ENGINEERING. 2 53 are precisely the same as those on Inchgarvie, while in the Queensferry south-east and south-west, and the Fife north-east and north-west, both longitu- dinal and lateral movements are provided for. The former is for expansion and contraction between the fixed circular piers and the cantilever end piers, the latter for any lateral deflection in the same length due to wind-pressure acting at right angles, or nearly so. In the cantilever end piers lateral centre. The central part, or oblong key-plate, is 2| in. in thickness, and enters therefore to the extent of f in. into the upper bedplate, to which it is rivetted. This, however, is somewhat different in the three fixed piers, for here both the two segments and the rectangular centre-plate are all alike 2| in. in thickness, and the whole key-plate, 12 ft. in diameter, enters into the ujuper key-plate. The central piece is the only one attached by rivet- layers of plates of varying thicknesses, according to position. The lowest course of plates, placed longi- tudinally, is | in. in thickness, and in this is cut the recess which receives the key-plate of what- ever shape it may be. The next course is laid transversely — 1 j in. in thickness — and extends, like the first, over the whole area. The third course, laid longitudinally, again is f in. in thickness, but extends only for about two-thirds of the area on the side next to the horizontal connecting bottom member. This plate also takes the attachments for the bottom booms of the horizontal cross bracing and the horizontal diagonal bracing. (See Fig. 91.) A further thickness of plates, as a fourth course, occurs in the case of the fixed piers, to make up for the enlarged recess in these, and this course is formed under the base of the vertical columns oidy. These plates are stiffened by twelve girders of I section — about 11 in. deep, and running longi- tudinally — consisting of web-plates and four angles. The third and fifth girders on each side are omitted, the main webplates of the skewback taking their places. (See Fig. 90.) Transversely these girders are combined and stiffened by cell-plates, flanged on all four sides in a die. There are eleven rows of these, and upon them are set the main dia- phragms, which reach from the bedplates to the crown of the skewbacks. The remaining spaces on each side of the inner webplates, and between these and the outer web-plates, are filled by similar dia- phragms, and at the same distances apart. The sections and plans shown in Figs. 89 to 94 will fully explain these parts, which are of the utmost importance, because through them all the stresses thrown ujion or against the structure, must pass on to the supports. The lower half of the skewback is square in form, the upper half for about two- thirds is rounded, the remainder being squared in order to receive the attachments of the top booms of bracing girders mentioned above. The inner main webs are l in. thick on Fife and Queensferry and 1 in. thick on Inchgarvie. and these are carried through ARRANGEMENT OF RF.IiPLATES ON GRANITE PIERS. movement is prevented, but longitudinal movement provided for. It will lie noticed that the key-plates, with the exception of those belonging to the fixed cantilevers, are shown in three parts, an oblong centre-piece and two segments of a circle. Of these, the two segments are only 2 in. in thickness, and therefore simply fill up the recess in the lower bedplate, while yet, however, they admit and facilitate, as well as control, a circular movement round the ting, the wings simply are laid loose into the recesses. The square key-plates in the bedplates of the fixed cantilevers are fixed to the upper bedplate, and enter the lower bedplate to the extent of 1 in. only, the whole bedplate being much lighter than in the case of the free cantilevers. The upper bedplates form the under part or foot of the main junctions or skewbacks. These plates are, like the lower bedplates, built up of several from end to end of the skewback at a distance of 3 ft. 6 in. to each side of the centre line. These | plates form the main points of attachment for the diagonal struts and for the bottom members, both j within the central towers and in the cantilevers, j The outer webplates, 1 in. thick on Fife anti [ Queensferry and ! j in. thick on Inchgarvie, j receive the main thrust of the vertical columns, j and are carried on each side into the bottom J members by a change from the rectangular into [ the circular form. (See Figs. 92 and 93.) They are | considerably stiffened in these parts by horizontal diaphragms and by doubling plates of great j strength, and the skeleton work to which they are attached is gradually merged into the main beams [ of the regular section of the bottom members. The attachments of the five lattice wind-bracimr ! girders, although most ingeniously contrived, does j not call for any special remark. It will be noticed in connection with the skew- backs that the centre of the vertical columns does not coincide with the centre of the circular granite Feb. 28, 1890.] ENGINEERING. 255 bearing all round ; and after these were found to be satisfactory, the rectangular portion of the key- plate was raised up and rivetted to the upper bed- plate. This was then lowered down into its place to see how it fitted, and whether all parts of the key were in proper contact. After thus lowering and raising it several times (a weight of about 57 tons), the surfaces were carefully cleaned and thick brown oil of a special character was poured into the key recess and on the whole area of the lower bedplate, and the upper bedplate lowered down upon it for the last time. Nothing else but oil was placed as lubricating medium between the two surfaces. The movements described in connection with the keyplates require that a certain amount of play be given in the holes of the upper bedplates through which the holding-down bolts pass. The amount of play varied, of course, in the same manner as with the key-plates. The lower bedplates being fixed and held down firmly by the bolts, it was necessary that the nuts should lie screwed down upon them. These nuts, shown in Fig. 95, were therefore arranged with a long neck, circular in form, and with an en- larged head of hexagon form. The holes in the upper bedplate had to be therefore made of such size and shape that with the nuts screwed down tightly upon the lower bedplates, with a consider- able stress upon the holding-down bolts, the upper bedplate could yet move in any desired direction without hindrance. This was done by means of a washer of oblong form placed upon the carefully-bevelled sides of the cells in the bedplates, which had bolts passing- through them. The nuts were first put on and screwed down by means of a hydraulic spanner — that is, a heavy box spanner with a short lever on the top of it, to the end of which a hydraulic ram was applied with a given pressure. This assured ram attached, 4 in. in diameter, which was forced into a cylinder already charged with 1000 lb. pressure water. The 4-in. ram forced the water to a small accumulator, loaded to produce a pressure of 3 tons per square inch. It needs no saying that this was a tedious kind of work, and took a long time to accomplish. On many days not more than half a dozen rivets were done — at no time more than about a hundred in the twelve hours, and the average would not probably amount to more than twenty-five per day. Meanwhile staging had been erected between the piers on trestles of certain height, upon which were put together the horizontal tubes connecting the skewbacks and the cross-girders and diagonal girders. All these were now connected to the skewbacks, and preparations made to rivet them up. All the erec- G) C2D Fig. 96. ED 1 ( r UZZT1 — .. ;i ji sw ii II 2 N » jj I jj sw il ii pi nn - a I !• __ : 'j |i Di::. !i / 1 \\ •' j! J 1 : 1 Inch- Garvi Pier (^) © Fife Pier. a — l 5 £ t-P i I; i ) N.E ii if “""V"! II si. ; \ ;j ji • [ | nl -\ !i •; ii » 9838 N BEDPLATES ON INCHGAEVIE AND FIFE PIERS. an even stress to all the bolts. The distance between the side of the cell and the under side of the head of the nut was then carefully callibered for each nut, and the washers made to that measure- ment, one-sixteenth of an inch being allowed for play. The sizes and shapes of the holes in the upper bedplates are shown by the diagram here given, the holes for Queensferry bedplates being, of course, the same as those for Fife, but in reversed position. (See Fig. 96.) The building of the skewbacks could now lie proceeded with, and this was done in such manner that the work as erected was at once rivetted up by machine. The most difficult places to get to were the lower edges of the inner and outer webplates, with their double angles already rivetted to the bedplates. All the work in, these cells which could not be done previous to the put- ting in of these plates had to be done by small hydraulic rivetters. These were simply cylindrical rams of 4 in. to 6 in. diameter, and in length from 6 in. to 10 in., and these were worked by a pres- sure of 3 tons per square inch. The cylinders were placed to either side of the rivet to be struck, facing each other, and backed by hardwood pack- ings against the sides of the cells, and the pressure water was supplied to them through small copper pipes about f',- in. in bore. The rivets were heated on the outside, and passed through holes in the webplates ; one cylinder was set against the rivet- head, and the other then closed upon the free end, and formed a flat head, the hole on that side being somewhat countersunk. To produce the 3 tons per square inch pressure, a multiplier was used, con- sisting of an 11-in. ram, which was acted upon by an ordinary accumulator pressure of 1000 lb. per square inch, and which had at its end another tion of the lower portions of the central towers was done by 3-ton or 5-ton steam derrick cranes placed on platforms at some height from the deck and in convenient position to pick the material off the bogies and at once place it in position. For the rivetting of the latticed girders the ordinary fixed or jointed machines were used, which are extremely simple in their construction and their action. (See Figs. 97, 98, 99, 100, the three first representing fixed machines, the last a jointed machine.) It depended entirely upon the places where rivets had to be struck whether one kind of machine or the other was used; but the direct-acting machine was surer in its action, because the double lever arrangement was apt to twist, and thereby bend the unclosed por- tion of the rivet before the latter was properly staved. Of course the longer the arms the greater becomes this tendency, and as some of the jointed machines had to be used with the arms fully 4 ft. 6 in. in length, great care had to be exercised to get good work done. The horizontal tubes, built up of heavy plates lj in. thick, required a special machine for rivet- ting, and as this machine is the same, or at all events typical of others, which were used for the rivetting of the bottom members, the vertical columns and the diagonal struts in the central towers, a brief description will not be amiss. T 11 the main it consisted of two circular girders, the inside diameter being about 1 ft. larger than the outside diameter of the tube. They were placed some 24 ft. apart and tightly wedged by hardwood blocks all round the tube. A box girder of a strong section, and about 25 ft. long was placed upon the ring girders in such manner that it could be pushed completely round the tube, and for this purpose hydraulic rams, one at each end were attached in such a manner that they could be fleeted forward or backward as desired. Upon the box girder a cylinder was placed facing the tube, being con- nected to a saddle which was capable of sliding from one end of the girder to the other. The saddle was worked by a ratchet and pinion, the latter working upon a rack which ran along the whole length of the girder. Finer adjustment could be given by two screws and handwheels on the saddle, like that of a lathe. By this means the centre of the cylinder could be brought opposite any point of the surface of the tube within the length of the girder. On the inside of the tube a mandrel or central hollow shaft was formed of the same length as the outside girder, and this was supported at both ends by frames fixed and wedged to the skeleton frame of the tube. On this mandrel a toothed rack was fixed, and a saddle worked by ratchet and pinion could move from end to end. Upon this saddle a cylinder of the same size as the outside one was placed with a long snap or dolly reaching to the plates. The supply of pressure water was so arranged that both cylinders would be turned on simultaneously, but by means of a check valve placed upon the outside supply pipe, the motion of the outside ram was slightly retarded. The girder outside was now placed in line with a row of rivets in the tube, and the inside cylinder was set opposite the same row. The rivets were heated in small fur- naces or forges on the inside and heated to a good yellow heat. As soon as a rivet was put into place the inside dolly was set against it, the outside ram being also set down, a tap given to indicate that all was ready, the pressure was turned on, and the rivet closed. The two cylinders were then moved forward, one pitch to the next hole and so on. When a whole row extending over about 18 ft. in length had been done, the girder was raised or lowered as the case might be, to the next row, and this continued until the whole section of the tube was rivetted. The machine was then moved 18 ft. forward and the process repeated. No drawing of these rivetting machines is given here, but a machine similar in construction, and used for rivet- ting the vertical columns, is shown further on. Between 600 and 700 rivets could be put in by this machine per day, all rivets here being 1 y in. in diameter. Only the rivets passing through the thick outside plates and beams were done by the machine. Of these there were about 1550 in each section rivetted, or nearly 100 per foot run. The other rivets, in diaphragms and beam-covers, were done by hand. The least number of hands to work this machine were three men outside and two men and a boy inside, with a lad for heating the rivets and a boy to carry them. The members of entirely circular form were the vertical columns, the horizontal tubes or bottom members between skewbacks, and the bottom mem- bers in cantilevers from the skewback to the end of bay 4. In design and in construction they were all the same — differing only in diameter — in the breadth and thickness of the plates, and in the depth and strength of the longitudinal beams. All plates are made, except in special places or for closing lengths, of a uniform length of 16 ft., and the tube is formed of ten plates, lap-jointed, and therefore consisting of five outer and five inner plates. All plates break joint at 8 ft., or half length, with an absolutely close butt, and the butts are covered inside and outside by plate-covers. The lap-joints are covered on the inside by ten con- tinuous girders of T section, the T head being rivetted in with the lap-joint, and two continuous angles are rivetted to the other end of the web, thus making the girder of double T or H section. (See Figs. 68, 73, and 94.) The beams are made in lengths of about double that of the plates, and break joint in different places, and all their joints are covered both in the webs and flanges. At every butt — that is, every 8 ft. — is placed a circular girder or diaphragm, which consists of ten wings placed be- tween the beams and rivetted to the shell, the wings projecting beyond the beams to the extent of about 3 in. An angle-iron ring running right round takes up all the wings to its web, while its heel is rivetted to each of the beams in succession, and thus com- bines the whole into a stiffening girder. At consi- derable distances apart, heavy plate-diaphragms are inserted which only leave a manhole in the centre to pass through. All these diaphragms are primarily for the purpose of preserving the true circular form of the tubes, and to prevent flattening; and it is a curious fact that the stiffest of these tubes, although bolted together in the most careful manner, flat- 2 5 6 tened before rivetting as much as 3 in., and had to be constantly strutted with timbers to keep it in form. The plates forming the shell of the vertical columns varied in thickness in the case of the Fife and Queensferry central towers, from -1 in. at bottom to $ in. at top ; and, in the case of Inchgarvie, from K in. at bottom to -/g- in. at top. The beams de- creased in strength proportionately. The diagonal columns or struts in central towers are of different shape, namely, circular top and bottom, but flattened on both sides in order to facilitate their intersection with each other and their entering into junctions top and bottom, where they are gradually changed into rectangular section. It lias been pointed out in the general description of the bridge, that the effects of the live load upon the Inchgarvie cantilever are different from those in the Fife and Queensferry piers. The diagonal struts in the former case are therefore very much stronger than in the latter. The bottom and top plates are lj in. in thickness, while the corner and side plates are 1 in. thick. The intersection of these two struts at centre of the tower is very heavy, some 80 tons of metal being massed therein. The inside beams are of corresponding strength. These diagonal columns were rivetted in the case of Inch- garvie from top to bottom by a special machine of similar design as that for the vertical columns, but more difficult to work on account of the angle at which the machine was placed. Meanwhile, steam derrick cranes were erected on platforms raised some 30 ft. to 40 ft. above deck, commanding the whole of the skewbacks, and these were now built with portions of the diagonal struts, the vertical columns and the struts 1 in cantilevers, to as great a height as could lie reached by means of these cranes. All this work was put together as carefully as possible, the larger number of holes being drifted up, but it was only bolted together pending the necessary checks and correc- tions being made by means of theodolites. This setting out was a work of no small difficulty, seeing that the members had to be set, not only to an inclination towards the point of intersection, but had at the same time to follow the uniform batter of the vertical columns, and had therefore a strong tendency to lean to the centre of the tower. So soon as the vertical columns and struts had been built to a height of about 50 ft. above deck, to which, in the case of Inchgarvie, had to be added the central ties, preparations were made for the construction of the lifting platforms, by means of which the central towers were raised to their full height. A staging, reaching on each side, north and south, from column to column, about 25 ft. in width, was raised from the deck to a height of about 38 ft. above the level of the staging, and upon this a pair of longitudinal girders were built. These girders were about 190 ft. long in the case of Fife and Queensferry, and 350 ft. long in the case of Inchgarvie. (See Figs. 101 and 102.) There were four girders — one to each side of the vertical columns — placed 18 ft. 6 in. apart, with angle cross bracings top and bottom, and diagonal bracing between top booms on one side, and bottom booms on the other side, alternately. The main booms, D D, Fig. 101, and most of the vertical angle bracing, were permanent work, being, in fact, the booms belonging to a portion of ties 1 in the cantilevers borrowed for the occasion. This plat- form and all its details are shown in a large number of the text illustrations as well as plates. During the time these girders were being put together, a strong box girder C C was built on a staging between vertical columns east and west, which girder passed through openings left in both columns, and projecting outside of each, to the extent of about 4 ft. or 5 ft. For this purpose one plate was left out on each side of the vertical columns during the time the girder passed aloft. This girder in its turn was supported upon a slide- block inside the vertical column, which block was attached to a cross-girder B B. This cross-girder was r 'f double box section, all in plate, and in its turn was supported by a number of pins about If in. in diameter, which passed through girder and through holes drilled for the purpose in four of the H beams of the vertical columns. Immediately below this box girder, and at a distance of about 1 ft. from it, was a second box girder of the same dimen- sions A A, and held up in the same manner by a number of pins. Upon the lower girder was placed, on a rocking underside, a hydraulic ram G G 14 in. ENGINEERING. [Feb. 28, 1890. PORTABLE HYDRAULIC R 1 VETTERS. ENGINEERING. 257 Feb. 28 , 1890 .] in diameter, with a stroke of a little over 12 in., the cylinder and ram passing through the upper box girder. The head of the ram acted by means of a swivelling cap immediately upon the cross-girder C C passing from column to column. The working of these girders and rams was as follows : — The lower box girder was held by a sufficient number of pins to carry the total weight placed upon it, but as soon as a small amount of pressure water was allowed to enter the ram, the latter lifted the cross- girder C, and with it the box girder B, to a small extent. The pins coidd then be withdrawn, and the girder lifted 6 in. or 12 in., as the case might be. The pins were then driven through the sides of the girder into holes newly exposed, and the beams and the weight let down upon that girder. The pressure was then allowed to pass on the top of the ram, and the cylinder was drawn up to the ram, bringing with it the lower box girder A. every few feet of lifting to the extent of the batter of the vertical tubes, which is 1 in about. (See Plate IX.) With every few feet of lift these platforms had to be pushed together, which was done by hydraulic rams also, and this accounts for the number of slide-blocks mentioned above. The ordinary routine in lifting was as follows : From a level position of the platforms the cross- girder in the north or south columns was lifted first 6 in ; next the other end was lifted 1 ft. ; then the opposite end 1 ft. ; and so on until sixteen lifts had been made, when a last lift of 6 in. at the end which commenced the lifting made the platform level again. When the platforms had in the first instance been lifted to a sufficient height, the rivetting cages were suspended from the under side of the platforms, and in subsequent lifts they were always On the inside of the platforms at each end were hoists worked by wire ropes from winches placed on deck, and all plates, beams, and other material was brought up by means of these hoists and dis- tributed over the platforms. (See Figs. 104 and 105.) Two-ton and 3-ton derrick hand cranes were found the most handy for the erection of the different members, but a traveller, or Goliath, worked by hydraulic power, was also used. When a lift had first been made, the first work, as a rule, was to put in the two closing plates to each column which had been left out to allow for | the passage of the cross girders. The inner part of the rivetting machine was then drawn up, the whole machine fixed, and rivetting was at once commenced ; while above the platform a section was added to the vertical tubes and the diagonal struts. The platform on Inchgarvie being of so much greater length, and weighing fully 700 tons, When the holes in girder and beams had come opposite, the pins were driven in, and the same process could be gone over again. the arrangement as just described was placed in each of the four vertical columns, and in the case of Inchgarvie into the central ties as well, thus giving six points of support there, instead of four. The longitudinal girders were now placed upon slides on the top of the cross-girders passing from side to side, and the tops of the girders covered over with cror-.s- timbers, and decked with planking .3 in. thick. Thus there were two platforms about 25 ft. wide by 200 ft. long, or 350 ft. long in the case of Inchgarvie, embracing completely and projecting to some distance beyond the vertical columns. Figs. 103, 104, and 105 show various positions and details of platforms. At the starting-point just above the skewbacks these platforms were some 110 ft. apart, centre to centre, approaching each other, of course, with 1 drawn up with the platforms. (.See Plate IX., rivetting cages on Inchgarvie.) This cage simply consisted of a stout circular wire cylinder being placed round a rivetting machine, similar in con- struction to the one described for the horizontal tubes, but hung vertically. Inside this cage the men worked with perfect safety as regards falling themselves or dropping things down on those working below. (See Figs. 106 and 107.) The portions of the rivetting machine inside the vertical column were not drawn up by the lifting of the platform, but were lifted separately subsequently. The length of the plates in the vertical columns being 16 ft., the lifts of the platforms were of the same length. The vertical columns were always built above the platforms to any height which could be reached with the cranes or other means at disposal, while the diagonal struts were at times built above, at j times below the platforms. had to be provided with two additional supports, I and these, of course, were carried upward the same as the vertical columns. The water pressure for lifting was supplied by a 1 special set of pumps which produced a pressure of 35 cwt. to the square inch. No accumulator was used, but the pumps simply forced up the rams gradu- ally. Under this great pressure the cup-leathers in the hydraulic rams and the leather washers in the pipe-joints, frequently gave way and caused much delay. Frosty weather also did a great deal in the way of freezing pipes to hinder the work, but after once the men had got into the way of working the plant, things went more smoothly. The first lift of the Inchgarvie platform took, with one thing and another, nearly eighteen days in the months of January and February, 1887 ; while the last lift, on the 9th of August of the same year, was accomplished in five hours. With the batter which the vertical columns and other side members 258 ENGINEERING. [Feb. 28, 1890. have towards each other, it is easy to understand that, independent of any weight which was im- posed on them, they would be liable to deviate from their true position. It was, therefore, neces- sary from time to time, that is every 30 ft. or 40 ft. , to secure the members by the interposition of temporary struts or ties either in the shape of lattice girders or of timber balks, and even timber trusses. Thus, after two lifts had been made with the platforms, the diagonal struts in the central easy to handle. The men also had become so familiar with the work that they knew exactly what was required, and made little account of the height at which the platforms had now arrived, namely, some 200 ft. At the next halt a great deal of work required to be done, namely, to build in the crossing of the diagonal struts in the centre of the pier. This for obvious reasons could not very well be done above the platform, but some 20 ft. below. In the case of tower, and a new start upwards could be made from a fresh fixed base. At this stage a prodigious amount of work was done, immense quantities of material were drawn up the hoist and distributed on the top of the platforms where the platers, working on tall ladders, bolted up beams and plates often 25 ft. above the platforms. Between the top of the platform and the bottom, men were at work remov- ing and replacing temporary bracing, which came in the way of the diagonal struts as they were built Fir,. 103 Golialh Gohalh ERECTION OF TOWERS. towers had not only deflected downwards by their own weight, but had also deflected towards the centre line of the bridge. It was not possible to go any further without putting them right, and this was done by girders placed both longitudinally and transversely between the struts, and using hydraulic rams to push them apart. In the case of the vertical columns the same difficulties arose, and here strong timber struts were interposed. For the same reason, the first diagonal bracing between these columns was kept up as close as possible to the platform. (See Plate X.) Nor was this the only matter requiring care, for although these columns might be kept the proper distance apart from each other, yet might they also both deflect in one direction, be this east or west, north or south. With the heavy platforms carried on these comparatively unconnected members, a strong wind from one side or the other could pro- duce serious distortions and deflections, and the rivetting up of the vertical columns following so close upon the rise of the platforms, made them so stiff that it was not easy to deal with them. In checking the columns, reference was always made to the centre line of the bridge, which was thrown upon the cross girder which carried the platforms, and measurement from this centre was taken to eacli side. That side which deviated least was first dealt with and pulled or pushed to the right posi- tion ; there it was held by wire rope ties or timber struts, and the other corrected subsequently. This cross-girder itself was used for pushing the columns apart or in, one side being fixed for the time and the other left loose. The first thorough correction was made at the top of the first vertical wind-bracing between the columns, where a solid plate girder passes right across, which carries the internal viaduct girders. This is shown in Plate X. The large gussets were fixed to the columns, and the booms of the latticed girders brought up to them. But the gussets were not yet drilled, and only after the position of one column had been ascertained and corrected, these holes were drilled, and the corner booms fixed. A fixed point being thus obtained, the other column was either pushed out or drawn in as the case might be, and the booms fixed in the same manner. By this time the platf< >rms had already approached each other to half the original distance, and all the temporary girders became much shorter and more Inchgarvie this crossing contains 80 tons of steel on each side, and at the crossing of the vertical tie at centre, and the horizontal bracing occurs at the same point, a very intricate piece of work required to be done. Here the vertical columns could be corrected for position north and south by means of the horizontal bracing which runs longitudinally from one vertical column to another, intersecting the crossing of the diagonal struts. A pair of horizontal bracings are also placed here between the four columns as shown in Fig. 4, Plate III. A strong framework, similar to the one immediately above the circular granite piers, thus closed the lower half of the central up. Inside the columns, the hydraulic men were busy preparing for the next lift and examining the caps, leathers, and pipe joints. Below these in the cages and inside the tubes, the gangs of machine rivetters vied with each other which could get done the quickest, a premium being paid to the squad that had done its section first. Again, below the cages, men were replacing diaphragms and other details of the structure which had been removed to allow the lifting girders to pass, and still lower down, squads of hand-rivetters were rivetting up beams and diaphragms, and putting in such rivets as the machine had not been able to do. Besides these a host of other men — carpenters to put up K Ei3. 28, 1890.] ENGINEERING. 259 stages, gangways, timber stiffeners, floors, and all sorts of things ; men attending to the rivet furnaces and trying to keep the machines going which put in their eighty to ninety rivets every hour, electric lightmen shifting lamps, putting in carbons and fixing fresh cables, and finally the hundred and one men who never seem to do anything, and yet cannot somehow be spared. At last the tops of the platforms have reached their final position ; and they can go no further, although the superstructure itself has to rise some 20 ft. more. (See Plate XII. and Fig. 108.) The two jjlatfonns by now have come so close together that the inner hoist-frame on one side had to be removed previous to the last lift. The long box girder now projects a long way outside each column, and stands now clear above them; the whole platform looks as if a heavy gust of wind would lift it up and throw it over the side. The last length of beams and the closing lengths of the plates require to be measured before they can be and an initial stress was put upon them by inter- posing hydraulic cylinders between the timbers and bottom booms of girders, and filling the space made with hardwood blocks. Blocks were now laid down on the top of the plat- form in the centre line of the top members, and the vertical webs of the bottom booms, the flange angles of the same laid down, and so soon as the top junctions were somewhat advanced, they were connected up at each end. The object was to relieve the platforms as soon as possible of any weight from the top members. The vertical brac- ings were then put on, and in these the webs of the top booms placed. The girders could now carry themselves, and rivetting was commenced as soon as the top junctions had been fixed and securely joined to the vertical columns. As there was a great deal of work to do upon these top junctions, they were completely surrounded by timber frames covered with boards, and provided with windows and a large number of electric lamps. Thus pro- horizontal cross-girder between top junctions (the two latter not shown in the engravings). The main strength of this junction lies in a number of very large webplates carried on each side of the centre in direct continuation of the webs of the top members. Inside these are the starting-plates, or horns, as they were popularly called, of the diagonal struts, and outside them those of the first inclined tie in bay 1 of the cantilever. Diaphragms, supported by stiff beams with a gradual change from round to square, connect it with the vertical column. The flanges of the top booms of the top members are carried right through, but the flanges of the bottom booms are replaced by extra plates and heavy angles. Most of the rivetting of the main webs was done by ordinary hydraulic rivetters, but a large number inside the cells, by small rivetters at the 3-ton pressure of similar construction as those used in the cells of the skewbacks. The top junction is shown in Figs. 109 and 110 in elevation and plan, HYDRAULIC TUBE RIVETTING MACHINE. and requires no further explanation. The rivet- ting of the top member between vertical columns was now pushed on as much as possible, and, as soon as completed, the working platform was transferred to the very top of these girders, and the removal of platform girders and all hydraulic lifting gear, commenced. This was all the more necessary since it will be remembered the platform girders were made out of portions of the first inclined tie of the cantilevers, and was now at once required to till its proper place in the structure. Many of the plates and illustrations show details in connection with the lifting plat- forms and the work carried on upon them, but the space here is not suificient to enter into description of them all. The Members forming the Cantilever. cut to length. Once more the columns .are care- fully set to the centre line of the bridge and to north and south, and the levels of all the beams in the columns taken. While these are being got ready, the gap of about 9 ft. between the two platforms is covered over, and only one platform exists now of more than double width. The longitudinal platform girders were stif- fened and trussed by link chains stretched from support to support. These chains were portions of the Hammersmith Suspension Bridge, bought up by the contractors, and largely made use of here in various ways. But the workmen would not consent to use the whole title due to them, for some of them called them Hammer links, and others called them Smith’s links ; but it required a Cockney by birth or adoption to get the combina- tion. These links were passed under double timbers, right under the two girders of each platform, t.ected the work could be carried on day and night, and it was necessary, for every beam and every plate had to have its correct measurement and shape taken before it could be made. The ends of the diagonal struts, changing from a flattened round into a square, had to be templated in every plate and beam to make an exact fit. It will give an idea of the magnitude of the work when it is stated that these wooden buildings, of which there are four to a pier, erected at a height of 360 ft. above the water, were about 24 ft. square and fully 35 ft. high, with three floors at different heights. The top junctions, although not of such impor- tance as the skewbacks, are yet fully worthy of more than a passing remark. (See Figs. 109 to 115.) Here are united two tubular members — the vertical column and the diagonal strut — and five latticed members — the top member in the centre tower, the top member in the cantilever, the first inclined tie in the same, the highest of the four wind-bracings between columns, and the The bottom members from their points of junc- tion with the skewbacks are not curved but are carried in a straight line to the first bottom junc- tions. At the centre of these junctions the angle alters and the members continue straight to the next junction, and so on till the end of tire cantilever is reached. At. each change the angle becomes more obtuse, until in the middle of the sixth or last bay the members are all but level. Looked at on plan the bottom members are 120 ft. apart, centre to centre at skewbacks, and 32 ft. 2 in. at the end posts — the centre lines being straight between these two points (see the plan in Plate III.) The diameter of these members at the skewback is 12 ft. , and the form circular, and the same form continues till the end of bay 4, where the diameter is 6 ft. 6 in. — a gradual taper being maintained throughout. Be- tween the end of bay 4 and the centre of bay 5, the form of these members is rectangular with a curved outside, and after this a plain rectangle on all four sides of varying height and width, until at the end of the cantilever the form is a square of 3 ft. THE FIFE AND QUEEN SFERRY PIERS. 260 ENGINEERING [Feb. 28, 1890. Fig. 107 . Skew back on fife pier. Fig. 108 . Queensferry pier from the river, 262 ENGINEERING. each way. The thickness of the plates in the bottom members is lj in. at the skewbacks, gradually de- creasing to | in. at the ends. The same mode of construction with longitudinal beams and transverse diaphragms of circular or other shape is followed to the end. In all the bottom junctions the main strength is concentrated in strong webplates into which the circular tube is gradually transformed, curved plates being placed on the outside of these webs to maintain the circular appearance on the outside of the junctions. (See Fig. 12.) To the main webplates the hornplates of the ties pointing backward, and these of the struts pointing for- ward, are attached. Except that the winding of the outer shell is perpendicular instead of horizontal, the construction of those junctions in principle is similar to that of the top junctions at the head of the vertical columns, but turned upside down. The changes in the form of section in the bottom members are indicated in the general elevation, plan, and side elevations of the cantilever in Plate III. The top members (see Fig. 116) or principal tension members are lattice girders of rectangular section, consisting of four main booms, which are braced on four sides. The webplates are carried through the whole length of the girders unbroken, only changing in depth and thickness, or in the number of thicknesses. The vertical side bracings — angles alternately on one side and other side of the webs — are double-crossed throughout. The horizontal bracing is not attached to the top and bottom flanges, but to a special plate attached to the web by angles on each side, and called the horizontal web. The horizontal bracing is also of angle bars, but for the most part in single or zig-zag fashion. The top flanges run right through to end of bay 5, where they disappear, the two web angles at top and bottom supplying a sufficient amount of section. The bottom flanges run up to the top junctions only on the inside, but right through on the out- side, the loss of section being made up here in other ways. Like the junctions in the bottom members, the webplates in the top junctions are stiffened or doubled, and receive the hornplates of struts and ties, with which they form a very strong framework, stiffened by bulkheads or diaphragms. The inclined struts (see Fig. 117) are flattened on the sides to facilitate their intersection with the ties and their attachments to bottom junctions and top junctions. They are, however, changed in form altogether in their extremities — being made rectan- gular the same as the diagonal struts in the central towers. A number of diaphragms are placed in- ternally where these changes occur, to keep the struts in shape. The thicknesses of plate vary between 1 in. and § in. according to position. Their construction is on the same principle as the other tubular members — lap-joints on the circumference — butt joints at ends — all plates being 16 ft. long, breaking joint every 8 ft. with a diaphragm at each joint. Struts 1 and 2 are made up of eight plates ; struts 3 and 4 of six plates ; and strut 5 of four plates on the circumference. As seen in Plate III. all struts in the cantilevers are braced and stiffened by diagonal wind-bracing girders of box shape, consisting of four corner angles with double or single cross-bracing on all four sides. These are attached to the struts by plate gussets and reverse angles. One girder is generally carried right through, the other is in two halves and is carried across by strong reverse angles and stiffening plates. At the heads of every pair of struts a horizontal lattice girder is placed between top junctions. The tension members are all of the lattice girder type with four main booms of T shape braced on all four sides. The section of the main booms is made up of one or several webplates, and one or more flange plates, with angles to connect both together. At the point of crossing with the struts the inner flanges are cut away and the section thus ost is made up in some parts, by a deepening of the web and by a doubling and strengthening of outside angles on either side in the same manner as is done in the case of the flanges of the top members when passing the heads of struts and ties in the top junctions. At the crossing of struts and ties large and strong gusset plates are rivetted, into which are attached the so-called vertical ties. This is clearly seen in Plate III. These are also rectangular lattice girders consisting of four booms, or in the lighter ones of four angles cross-braced on all four sides, and to the lower extremities of these are attached the bottom members by means of bent angles and gusset plates. These vertical ties, although not attached exactly midway between two of both members’ junctions, serve to prevent undue deflec- tion in these members, and in the first three bays of cantilevers serve to carry the weight of the internal viaduct by means of a plate girder across, stiffened by diagonal wind bracing. In the tension members two top and two bottom booms break joint alternately, and all webs and flanges are double covered. The top and bottom cross-bracings are rivetted to the flanges, the side bracings to the webs. Diaphragms consisting of angles on four sides and angle cross in centre arc placed at suitable distances apart. The internal viaduct in the cantilevers is the same as described for the portion in the central towers. Figs. 119 and 120 show a portion of it in elevation and cross-section at the point where the viaduct is [Feb. 28, 1890. to be adopted to forward the work. A cage about 19 ft. square, and consisting of a number of sections each 8 ft. in length, was placed upon the bottom member. (See Figs. 105 and 106, and Plate IX.) It was so constructed that each sec- tion could be taken away at the back and placed in front, and this operation was performed by a hydraulic crane placed on the top of the cage itself. This crane has a jib of fixed length, which it could not alter, but it could slide up and down the top of this cage by means of hydraulic rams on each side. It could also slew completely round. The forward part of the cage was used by the platers for building up the tube, the beams .and plates and other parts being first brought within reach of the hydraulic crane and then swung round into place. The nearer portion of the cage contained the same rivetting machine which had already done service in finishing the supported in the centre of bay 1 (see Plate III.). The two figures are not drawn on the same scale, but otherwise refer to the same point. As the spans in the cantilevers become shorter the viaduct diminishes in strength of sections, and from the centre of bay 2 to the end of bay 2 in depth also. At the end of bay 4 the girders altogether disappear, and the four troughs are strengthened and carry the permanent way, being supported both on the cross girders and on the diagonal wind bracings between the cantilevers. All the various supports of the internal viaduct in the cantilevers are shown so clearly in Plate III. that it is not necessary to enter into further details. The diagonal wind bracings between the bottom members are also of rectangular box construction, consisting of four main booms made up in the longer girders by webs, flanges, and angles, and in the shorter girders of simple corner angles. They are double or single-braced on all four sides, and are joined by heavy gusset plates at the points of intersection. They are joined to the bottom mem- bers by large gusset plates top and bottom, clearly shown in Plate III., plan of bottom members. The removal of these platform girders, many hundred tons in weight, with all the odds and ends of a working platform upon them, was a w r ork which caused no little anxiety ; for upon nearly every portion of the structure below 7 , w 7 ork was carried on by scores of men to whom the fall of a small bolt, or nut from that height might cause danger to life or limb. The year in which the central tow r ers were erected shows the greatest number of fatal accidents in any one year, namely, 17, while the average over the seven years is only 9. Building out of the Cantilevers. Shortly before the lifting platform had arrived at the point of intersection of the diagonal struts or columns in the central towers, a commencement was made with the building out of the bottom members in the first bay of cantilevers. This was done as yet by steam derrick cranes, but their reach was limited, and other means had j horizontal portion of the bottom members between columns. For a length of about 64 ft. the bottom member w r as thus rivetted up in order to stiffen it as much as possible, and enable it to carry itself and the necessary plant at the point of it, unsup- ported for a time until temporary support could be found for it. (See Fig. 105.) As soon as the cage had got beyond the point of junction between the bottom member and the first vertical tie, that is, at centre of bay 1 (see Fig. 121), gussets w 7 ere attached to the bottom members close to this point and to the vertical columns immediately above the horizontal bracing between the columns, and a chain of Hammersmith links were fixed up betw'een these two points. On these links a tem- porary staging was suspended, by means of which a heavy plate tie — one on each side of the tube — could be inserted. For these ties also strong gussets were attached to both bottom members and vertical columns. To the gussets on the columns other gussets w 7 ere attached, and to these w 7 ere bolted horizontal plate ties, suspended to and immediately below the horizontal bracing girders at the intersection of the diagonal struts. A set of plate ties w r ere also placed at the opposite canti- lever, and balance thus established. These plate ties, both horizontal and inclined, were about 2 ft. 6 in. deep and of tw r o thicknesses of f in. plate, being, in fact, portions of the main webs of the top members in bay 2. Previous to the attach ment of these ties to the gussets, the bottom mem- bers were lifted up to the extent of several inches by means of hydraulic rams, in order that they might lie able to support their own and any further weight which might be put upon them during erection of the first bay. Most of these appliances are shown clearly in Plates, IX., XV., and XVII. The lower portion of the first vertical tie was then built, and a lifting girder laid across from one bottom member to the other, and a platform built on each side similar to those for the erection of the central towers, only so much smaller and lighter. These platforms were lifted by hydraulic rams in Feb. 28, 1890.] the vertical ties, and by the same agency along the vertical columns, and while lifting these in stages of about 16 ft. , the two struts 1 in cantilever and the vertical ties were built up. The use of lifting- platforms was abandoned after this; all the work of erection was done far more quickly and efficiently by the cranes specially designed for this work. Meanwhile, the top members had been completed, and a 3-ton hand-crane was set up on the top of each vertical column. (See Fig. 121.) The viaduct girders in the central towers had also been put together by now, and a new platform was thus secured about half-way up the erection. The viaduct girders were now built out by over- hanging into the cantilevers, and a length of top member as well, these two last being built by the 3-ton cranes on top, and by winch and tackle wherever such could be used. All the material for the viaduct level was hoisted to it, and for the top members, it was lifted right to the top. The viaduct girders were strong enough to carry ENGINEERING. drilled in situ. This junction was then at once rivetted up, and thus a new fixed point secured from which to proceed further out. (Plate XV.) In the mean time, the top member, Jubilee Crane, as it was popularly called (because it was invented, or at any rate designed, about the time of the Queen’s Jubilee in 1887), had been erected on the top of top member. This crane consisted of a square frame supported on two girders reaching over all four booms of the top members from side to side. The girders were of different heights, in order to get the platform on which the crane was placed level, and the girders were placed on slides, so as readily to allow them to move down the incline of about 1 in 4 when required. The crane itself had a horizontal jib with a reach of 34 ft., and could slew round, by means of a circular rack and pinion, to about 220 deg., or three-fifths of a full circle. It was worked by a pair of reversible steam [ engines, and had a large barrel capal tie of winding 263 put a tremendous strain upon the two top members, which were then still unsupported, and though they bore their load well it is evideut that the building of this first half of bay 1, was a work of great anxiety, lest a heavy gale should cause some serious distortions. As the top members were never intended to carry any load except their own weight, the vertical side bracings were not sufficiently strong to carry the crane without a risk of bending the bars. These bracings were consequently not only doubled by reverse bars running the full length with them, but the reverse bars were of a section double and treble that of the ordinary bracing bars. Templates for these bars were taken as soon as each section of the top member, was built up, and they remained in their places until the weight of the crane had passed beyond the next main support. Generally speaking this crane built all the members above the level of the viaduct, and of course below that level also if necessary. Its maximum lift was 3 tons, and with I Fic:. 120. Section of internal viaduct. themselves, overhanging for a length of 100 ft., and even then to carry at the forward end the weight of a 3-ton crane and its load, but, as a matter of safety, wire ropes were carried from the outer ends up to the top junctions on vertical columns. The top members also had to carry their own weight unsupported for a length of nearly 100 ft. The lifting platform in the first half of bay 1 was only carried up to about 20 ft. above the level of the viaduct, and there it remained. (See Plates XV. and XVII.) The first inclined ties in cantilevers were now brought down from the top junctions, being held up and in position by means of timber struts be- tween them and the vertical columns, and laterally apart by lattice girders from one to the other. (See Fig. 122.) The first struts had also been built up to some 20 ft. above the platform, and when the ties had been brought down to the point of intersection with the struts, preparations were made to make good their junctions. Previous to this the positions of struts, ties and vertical ties, were carefully checked, both as regards their meeting in the true centre as well as being the right distance apart from the centre-line of the bridge. Large gusset- plates, joining all three members together, were then placed in position and the necessary holes up about 400 ft. of wire rope. It carried its boiler with it, and was thus quite self-contained. Sus- pended from the two main girders of the frame was a platform, carried some 4 ft. to 5 ft. below the bottom booms of the top member, 64 ft. long and about 36 ft. wide, mainly supported on four light lattice girders. The planking of this platform was so arranged that it could readily lie taken up in every place where required, the four lattice girders being so placed as to pass all struts and ties and vertical supports in succession, the flooring only requiring to be taken up. The sides of the platform under the top members projected to within about 6 ft. of the end of the jib. In building the top mem- bers, the booms of which were in lengths of about 24 ft. , the crane could lift them from the viaduct level below and place them at once in position, the platform allowing safe ground for the men who had to guide them into place and bolt up the joints and cover-plates. The vertical bracings followed next, and then the top booms, and all other neces- sary work, and when both sides of the top member were built and well bolted up, the crane was pushed forward 24 ft. on to the newly built section. The crane with platform and all necessary gear weighed about 64 tons, which, placed at a distance of about 80 ft. from the centre of the top junctions, rare exceptions no portions of the work were made heavier than about 50 cwt. on the outside. As soon as the crossings between struts 1 and ties 1 had been made secure — a vertical support — a box lattice girder, was raised from that point square upwards in continuation of the vertical tie below, in order to give the top member the necessary sup- port. As this support formed no part of the finished structure it was made of iron only, but of fully sufficient strength. It required, however, both longitudinal and lateral support, and this was provided by carrying lattice girders at a point about two-thirds of the height between the crossings and the toji members on each side, from the ties 1 to the vertical supports, and transversely from one support to the other. Cross ties of wire rope were also carried up between the supports. As soon as the supports had reached up to within a foot or two of the top members, a further length was built to the latter, which reached right across the supports. By this time and with so much weight on them the top members had deflected about 9 in. to 10 in. , and hydraulic rams were now arranged to lift them up from the vertical supports, and give them their proper position, and place them as much higher as would allow for the probable compres- sion in the vertical supports. Meanwhile the lower portion of the ties 1 had been built from the point of intersection down- wards, the bottom member had been brought forward, and the junction of bottom members with struts and ties at the end of the first bay, built in. But the bottom members also had deflected, owing to their own weight and to that of the rivetting machines — the cages and the bottom junctions. It was, therefore, necessary to lift the bottom members up at this point, and to do this the following plan was adopted (See Figs. 123 and 124) : Four heavy angles were attached near the ends of ties 1 so far as they had been brought down ; these angles were of such length as to project some 6 ft. to 8 ft. below the under side of the bottom member ; two heavy box girders were now passed under each of the bottom members, the lower one being fixed to the ends of the four angle-bars, while the upper girder was brought up to hardwood packings, which gave it a full bearing against the under side of the bottom members. Between the two girders, hydraulic rams about 10 in. in diameter were placed. The action of the hydraulic rams in being forced out was, therefore, to push the upper girders hard up to the bottom members and the lower girders downwards, thereby putting a corres- ponding tensile stress on the ties 1. In the vertical ties 1, in the centre of bay 1, a joint in each of the four booms had been left open 264 ENGINEERING. [Feb. 28, 1890. in such manner that this tie could be shortened to a certain extent, its upper end at the crossing- being now an absolute fixture. By means of an arrangement of cross-girders and hydraulic rams this joint could now be closed to any desired extent, new cover-plates being, of course, required to make good the joint. All being thus prepared, a theodolite was placed in the centre of each bottom member, and these were lifted, both at the vertical ties and at the end of the inclined ties 1, by means of the hydraulic rams, until the members had risen to the correct angle and a trifle beyond, when hardwood packings were put between the girders, and wedges driven in, so as to secure the maintenance of their posi- tion. Thus placed, the holes in the new cover- and to give them the elongation proportionate to that weight. With this there were now, outside the central towers, two points established, the position of which was correct, and which were capable of sus- taining the full weight which they would have ulti- mately to sustain in the completed structure. The next operation was to raise the top mem- bers from the temporary vertical supports car- ried up from the points of crossing, and this also was done by hydraulic rams. The temporary supports raised from the points of intersection and carried to the top members were used at the centre of every bay out, becoming in each case much shorter and lighter. They had to be removed, owing to want of material for making a larger viaduct by the top member crane, swung into position, and at once bolted on, while the stage itself, when it required raising, was attached to the crane for the moment and lifted up, when it was attached again by chains or wire ropes to the strut itself. The tie staging was hung to stout rope tackle and let down by the men working on the ties themselves. As soon as the struts had been built up to a point close under the junctions with top members the latter had their position checked by theodolites, and, if required, they were upon these points also lifted by hydraulic pressure rams and then drifted up, and when in correct position were at once rivetted. Another fixed point was thus secured, plates making up the joints in the booms of the vertical ties were drilled at once, and the joints ri vetted up. The closing lengths of the booms of the inclined ties 1 were also measured, and templets made of them and taken to the shops. These lengths were then cut and drilled, and at once put into their places, and the whole of the ties finished up in every part and detail. The effect of these operations then was : 1. To secure the absolute correctness of the position of the first bottom junctions as regards tlie height above water, and their distance from the centre line of bridge. 2. To put upon both the inclined ties 1 and the vertical ties that stress which would correspond with their share of weight of the structure put up, number, frequently before the top members were ■ rivetted up sufficiently to bear their own weight and that of the staging which was attached to them, | and considerable deflection in some of the longer j sections was the result. The top member crane could now slide forward another section and build, not only the next section j of the top member, but also the upper halves of [ struts 1. These did not take long. They were j built from the bottom upward, in the same way as ; the inclined ties were built from the top downward. ■ For the struts light square stages fenced on four- sides were used, these being 15 ft. square and open in the centre to admit the strut. The stages were accessible by means of wooden ladders laid from bottom upwards or by rope ladders hung from the top. The bars and plates were picked off the and the first bay in cantilevers practically com- pleted. The plate girder, reaching transversely from one vertical tie to the other, and upon which are sup- ported the girders of the internal viaduct, had meanwhile been put in place, as also the diagonal bracing below it. The viaduct was then advanced over it and carried forward till it reached the first trestle at end of bay 1, which reaches across the first bottom junctions and gives support to the internal viaduct at this point. So far completed, all members were at their correct elevation so far as this could be secured, but it was possible, and happened frequently, that, owing to continued strong winds (no permanent wind-bracing was as yet fixed) from one quarter, a certain amount of displacement occurred. Thus, 265 Feb. 28, 1890.] although the bottom members might at the end of the first junctions be the proper distance apart from each other, yet the centre of an imagi- nary line between them might not coincide with the centre line of the bridge, but fall to one side or the other. Precisely the same thing might happen in the case of the inclined struts, and the top members thus lie to one side or the other of the true centre line. Nor was the wind the only factor that could produce such a result, for the fact whether the sun was shining on the east side or the west side of the bridge made a material difference. On the sun appearing the plates on that side of the tubular members on which its rays fell would expand, while on the other sides the plates remained as ENGINEERING. pletely, but the last or closing lengths outwards j were always left to be measured and templeted in situ. The gussets by which they were attached to the bottom members were already fixed and rivetted to the latter, and it remained, therefore, only to erect the girders in their places and take the templets for the closing ends. While they were being erected they were hung by wire ropes to the internal viaduct. Previous to this, however, the exact position of the bottom mem- bers had to be ascertained, and, if not correct, wire rope ties attached between bottom members and girders by means of union rews or timber struts, worked with wedges or small hydraulic rams, had to be employed to draw the bottom members in or push them out, according to requirements. This always so much greater from the west than from the east has something to do with it, the writer will not take upon himself to say, but appearances decidedly point in that direction. With the corrections in the positions of the struts and bottom members, the first bays of the canti- levers were now completed, and, except in so far as the elasticity of the steel came into play, all the points were as fixed as if each was resting on a solid masonry pier. The duties of the survey department in connec- tion with the erection of the cantilevers were of the heaviest kind. The work had to be carried on in the most exposed positions and in all weathers. To Mr. W. N. Bakewell belongs the credit of a great achievement, and it is not too much to say that to Fig. 122 . Erection of cantilevers. they were. This produced, therefore, a bend away from the sun, of an extent not inconsiderable, but, of course, only temporary in its action ; for, with 1 the sun turning to south and passing to west, the 1 members not only became straightened again, but became curved in the opposite direction. Errors in measurements and faults in construction might, of course, also produce similar and per- manent results, and it was therefore necessary to take steps to fix the position so far as it could be done. The diagonal wind-bracings between bottom mem- bers, of which the first pair starts from the skew- backs, now required to be dealt with. As neither bottom members nor inclined struts had ever been laid together in the relative posi- tion, the wind-bracings could not be built corn- done, the templets of the booms were taken and the girders completed. The same process had to be repeated at every point of attachment, that is, every half-bay out. The position of the inclined struts with regard to the centre line of the bridge was corrected in a precisely similar way, and by this means was achieved the successful building out j of these arms, nearly 700 ft. in length and weighing some 5400 tons, with an error of only 2 in. For an error there is, and, curiously, it exists in nearly all the six cantilevers, and in the same direction, namely, to east. Whether this is due to the pre- vailing westerly winds, and the fact that the total | west pressure upon the structure in the course of a twelvemonth must be probably fifty times as great j as the total from the east, or whether the fact that the lateral deflections due to the sun’s rays are his courage and decision and promptitude in fixing points, is due the saving of much time and much expenditure. From the first bottom junctions struts 2 were started upwards, and from the first top junctions ties 2 were started downwards, in repetition of the operations already gone through in the first bay. The bottom members were built out and the internal viaduct brought forward. Upon the latter were now erected — upon a staging sliding on the rail troughs — two steam cranes with movable derricks standing side by side, each being worked by a steam winch placed some distance behind. Wire ropes were exclusively used by these cranes, which, owing to their position, were called the twins. As the Jubilee crane, resting on the top members, built all the work from near the viaduct 266 upwards, so the twin cranes built everything from that level downwards. Up to this time most of the material of which the members were built was lifted by the hoists in the central towers, and brought forward on tempo- rary lines of rails to within reach of either top member cranes or cranes on the viaduct. From this point forward only the light material, such as bars, angles, and other things, were sent up the hoists, while all the heavy booms and plates were placed on board one of the steam barges, and hoisted up by one of the twin cranes to the viaduct level, and thence were taken by the Jubilee crane to the top. Somewhat later, again, when the top ENGINEERING. union screws being used in the place of hydraulic cylinders. The erection of bays 3 , 4 , 5 , and G was simply routine work — repetitions of the work gone through — and so much more easy for the reason that not only had the distances, both vertically and horizon- tally, between the members become so much less great, but also because the men had become so skilful and so accustomed to their tasks, that what ap- peared at one time to be insurmountable difficulties and hazardous undertakings, had now become mere child s play, and were done in those exposed posi- tions as easily as if the men were standing upon the floor of an ordinary workshop. [Feb. 28, 1890. by hydraulic rivetters, while the struts were rivetted 1 >7 hand only. The main booms of the ties were rivetted up in the yard as far as could be done by machines, and little more than the joints and brac- ing bars were left to do after erection. Of the internal viaduct also as much as could conveniently be got at was done by hydraulic machines, and the rest by hand. The booms of the wind-bracings were also rivetted together in the yard by hydraulic machines, and as they decreased in weight further forward they were rivetted, at times in the fidl square, at others tops and bottoms, thus leaving the side bracings only to be completed. THE members had still nearer approached to the water, the material for these, and for the upper portions of struts and ties, was lifted by the Jubilee crane out of the barge, and swung into place at once, thereby saving much time and labour. In the erection of the bottom members in bay 2 the temporary attachments necessary to hold them up in position were carried partly to the point of intersection of struts 1 and ties 1, partly to the first top junction, and there attached to heads of struts 1. Hammersmith Bridge links were used for the first and wire ropes for the second, no plate-ties being required. Later on still wire ropes were capable of dealing with most of the lifting required, “jubilee” crane on top members of cantileve The rivetting of the work followed the erection so closely, that many squads of rivetters were working upon the extreme ends side by side with the erectors. In the case of the tension members all the main joints were rivetted as soon as pos- sible after erection, and where such could not be done, all joints were bolted up with specially pre- pared turned steel bolts. In the bottom members the hydraulic rivetting machine was carried forward to beyond the end of the third bay, after which all rivets were put in by hand, particular care being taken to have all the work thoroughly well bolted up, and to put the best and most trustworthy hands to the job. All the tension members were almost exclusively rivetted RS. In the same way the lattice box girders between [ the struts were also dealt with ; they could be lifted straight into their places, the joints only and the points of intersection requiring to be rivetted. The top member was rivetted in all parts by hydraulic machines wherever it was possible to get the machine ap] died. F or this purpose two or three light timber stages followed at the back of the Jubilee crane, and here two or three rivet-heating furnaces were kept going to supply the various machines going below, the hot rivets being dropped down a long pipe, the end of which was stuck into a pail with ashes at the bottom. These furnaces were heated by oil and compressed air. It was thus necessary to bring along in the first instance from Feb. 28, 1890.] ENGINEERING. 267 the deck up to the tops of the towers, and then to each side down the cantilevers, not only the pressure pipes for the water working the hydraulic rivet- ters, but also for the supply of compressed air and oil to the furnaces. The oil was brought in pipes connected with a tank on the top of the central tower, and run down to the furnace tank by gravity. Queensferry and Fife. Bedplates and central towers 4816 tons each Two cantilevers ... ... 10,816 ,, Total 15,632 or Total ... ... 31, 264 tons for both Temporary angles For lifting bottom member Saddle For Trestle end of Bay 1. HYDRAULIC LIFTING ARRANGEMENT FOR BOTTOM MEMBERS OF CANTILEVERS. but with no result. Only divided by a gap of some 350 ft. it was now possible to take up a position in a gale of wind, and by fixing a point on the oppo- site cantilever end and another point fully half a mile further back on the shore, try to see what the lateral deflection might be. But, whatever its amount, it was too small to be noticed by the naked eye ; nor could any movement be felt | except a slight vibration whenever an extra heavy gust of wind would hurl itself against the solid face of steel plates. In setting out the centre lines in the vortical sense of the bottom members while building out plate by plate, allowance had been made at every junction for the natural and unavoidable deflection in the whole cantilever as a mass. This was, of course, also done in setting out the internal viaduct. It was intended that there should be in the free cantilevers a camber of 10 in. at the end posts when the cantilever was completed — that is, the line of rails at the end post would be 10 in. higher than in the central towers when no load was on the bridge. But to get this it was necessary to set each section higher by so much as it would deflect by the addi- tion of the remaining sections further forward. The point aimed at was, therefore, set another 10 in. up, or 1 ft. 8 in. altogether. This was, of course, entirely a matter of calculation and of judg- ment, and in the end the cantilevers arrived at the position in which they were desired to be. It remains now to tell how the central girders were erected and the final connections made. The end posts are hollow boxes about 4j? ft. deep and 3 ft. wide, by 40 ft. in height, and are closed on three sides, the fourth side towards the central girder being open. The bottom members project right to the end of the post, while the top members stop short at the closed or inner side, except the webplates, which, in the shape of large gussets, are also carried full to the ojien end. So far the four free cantilevers are exactly alike, but in the further arrangements they differ considerably, as will presently be described. The end posts of the two fixed cantilevers where they rest in the cantilever end piers are different from the above. Here the posts are re- , placed by a large box about 8 ft. long and extend- ing over the whole width and height of the end of the cantilever, out of which an arched way has been cut to allow the passage of the trains. An end elevation of this box is shown in Fig. 23 on a preceding page. The object of these boxes has 1 been already explained, and will be again referred to in connection with the expansion movements provided for at this point. They are filled witli cast-iron bricks and punchings and other scrap all laid in asphalt poured in hot and firmly set, thus preventing shifting and at the same time making the box water-tight. About 1000 tons of dead weight is placed at these points over and above the 1 weight of the steelwork. The central girders have already been described as having a slightly raised or curved top member of polygonal form ; that is to say, it is straight from one support to another, a kink taking place at the point of support, in the same manner as the 1 bottom member in the cantilevers. The bottom ! member is straight. The two are connected by ; eight pairs of cross-bracings on each side, inter- j secting each other at the centre and consisting of struts and ties. The girder is 350 ft. in length, Central Girder Cantilever Direction of Train running 9838 P Fig. 127. Expansion joint for rails at ends of central girders ; inchgarvie, north and south. With the last intersections built in bay 6, and struts and ties, top members and bottom members carried past them, it only remained to put up the end posts to complete the cantilevers. The weight which had now been raised upon the supports may be shortly stated as follows : Inchgarvie. Bedplates and central tower ... 7036 tons. Two cantilevers ... ... ... 10,750 ,, 17,7S6 „ or, on the three points, a grand total of 40,050 tons, not counting the approach viaduct spans at either end. But, apart from the permanent work, many hundred tons of weight in the shape of cranes, temporary girders, winches, steam boilers, rivet furnaces, rivetting machines, miles of steel wire ropes and of gangways, and acres of solid timber staging were suspended from these cantilevers. A heavy shower of rain would in a few minutes put an extra weight of a hundred tons, and the storm would try its worst against these immense surfaces, 40 ft. high at the ends, and 50 ft. high in the centre. It is divided into eight bays of slightly unequal length. The top members are braced together by 16 sets of diagonal lattice bracings, while the bottom members are connected by solid plate girders acting as cross-bearers, one at tire centre and one at the end of every bay, in addition to those forming the ends of the girders. Vertical ties are attached to each intersection of struts and ties and carry the bottom members between the bottom junctions. The bottom members are trough- shaped and about 3 ft. high by 2 ft. 6 in. wide ; Total DETAILS OF CONNECTIONS OF CENTRAL GIRDERS AND INTERNAL VIADUCT. 268 ENGINEERING. [Feb. 28, 1890. the top members are inverted troughs of the same varying strength and section. The joints in top and the flooring in the central girders are made up , the footpaths— were made up of buckle plates uimensions. itach pair of opposite struts is con- booms and bottom booms were so arranged that much about the same as in the cantilevers, with supported on T bars from trough to trough. ec •, y two I' alrs ot diagonal wind bracings eacli half-bay could be built out in succession, the four rail troughs and two footpaths, and a wind Previous to the exact lengths of the central a .°"’ n , as , low a f , fche P assa ge of trams wdl length of boom just reaching beyond the junctions fence on each side. The 6-ft. way— the space girders being fixed the distance between the canti- ' ‘ An struts and ties are of box shape of or beyond the vertical ties. The permanent way between the two troughs of each line of rails and levers had been measured carefully and frequently CONNECTIONS OF CENTRAL GIRDERS AND CANTILEVERS. Feb. 28, 1890.] ENGINEERING. 269 * Ow ce 72 -J-3 Jh O 0 CD CD bD , 0 cd 2 ^ r o r C : K*"i. r- ’’G c3 bD G 0 2 ~ . g> g ^ G 5° o 0 0 < G Tj ’bO CD 0 0 _s ^ 0 ■+5 -H> r- ’ 0 G G O rG 0 .£h H-P CQ ^ ' bD sn ff*. ^ — . £ 0 ~ 0- 0 C -*- 3 rj 0 r o © •rH > 0 r& -g H> bD „ bD ce d 5 cZ > . o 4 h G co * r! < ^ 2 ^ n 5 G g 0 53 5 X O^. > sc-o o "S o c3 .G 1— 1 ' c 0 0 cq 0 .y ^ -4— < ' “* 0 . o 72 72 ^ g ~o > ®' s §U 2 O Cj 0 rj ,JJ PhO- "G 0 n=: -h rG G g cfl " 'g ^ J 1,2 Hi H 72 H iljgc/} G *G & te -C s ^ osci ^ c3 Hi Q2 0 0 w .3 ce x • 0 ) bJ3 jq 0 £ o 0 «r bi)i Hi 3 0 O 0 rG 73 0 Hi CS blj,_0 G 02 , 72 O 0 O r 02 r-H ^ o 72 0 2 0 S^h O ^ _g M .-g £ '3 d s v? g ce ce G 0 .2 CD 0) g ^ g°G sc P H 02 p cs H bD £ +3 ‘-p . 0 . r 7 s 0 H O ci ; co -H 0 >rH G § 0 72 0 G jU O +* PhH 3 rG O c5 'CO H 72 1 4 i>- 01— I -1-3 -H> r - 0 0 bD 0 0 0 ■ I — I ® -p O -D O £ H po ,0 3 « -p ■ H -f Oh rr _Q 72 G S £ m- 60 «s 23 O cg'g g .2 0 72 0 1 ) -P fi, 72 • • : o 02 f- 2 x --O ^ — 0 _ Pd £ 0 ce ^ bo & S o p. 0 ^ 0 •G 72 !> J2 O rl^ 0 C ^ CO . ce 0 1 600 “ ° 5 ^ co ce ^ • J a'fl 2 * | f D £ g s ■§ .s « O 0 0 . 02 c >> 2 w -»p> O ?c? 2.2 ^ 02 3 bD p ?r5 co 0 G # g ® ’be ^ 0 r— I 0 G 0 g -V 0 m egg * S-S. 0 02 P 0 O -£ O D Ct 0 o2 0 0 ce- co *: ^ 0 ^ 0 pj 0 "S .2 fc* . Q -O r— ; 4P^ p ce 0 ce 0 0 — 72 £ 0 o-ls-s: ce 1 0 <4-< c o Q2 G O , . Cw Dh 0 - 'ri ce o 00 n e e 0 m 1e 2 Ph ce U £ 0 00 £S? 0 ^ -0 _ b. I-* J3 — bD 'rt 1 .s r- o ^ 0 0 O g K -p ^ y ^.1 o'g M CD'S P C'C ^ is o« OO . G G 0 0 , bD 0 <-G r—i CO c 02 o ^ X 0 rP 8 '&J s, : co o 02 0 0 Q 0 1 • G ce m ^ ^ g 0 0 0 0 CO , rG rG D ! ’G ce 03 g "« ® . 43 r\0 ^ ^rG 0 O 0 Sol < 72 bO bDO-1 S 'DH 0 Hi iO * r-H -+-> G M H O ce 0 0 p • r-s 72 _0 0 0 0 0 0 'rS PH, o S 0 pD ci ^ Ol G 0 T •G -SP G bD 3 co 0 ^ S^.is g^l aj^ 3 rP OH CflP ce-PiH 0 G 0 0 • G • -H> 0 ? X 0 -g 0 W P p G {>> 0 H C bD •■ 0 0 *S bD ' j o 0 HJ Ph G 0 0 4P 43 hG 0 Gh 0 0 ^’2 72 X rp ' 0 r < 72 72 G bD ^ 0 43> 0 bp o -43 72 rj -H 1G 0 .G G rH 0 02 ce HgJ S a h „ Eh m 05 3 .g ^P'-g Hi 0 bD ^ O Sgsg s a ^ o® s p- -p ci -p, G j_. ce ce 0 G . 0 0 ^ 0 -g g o X § p< “? <« s rH 0 PH 0 72 Sh -h I! T| G 'bD 0 ^ 3 rG H »0 3 £ ^G ^ 0rP 2 X c l >^H , rG J G 0 O rG • ss§^ o 0 .22 0 Sh ENGINEERING. 270 bottom, allow a horizontal movement of the whole girder round the centre of the pirns, while yet allowing no lateral movement of any kind except that which may be due to the mere hair’s-breadth of play in the slide-block. At the Queensferry and Fife ends, however, these blocks are absolute fixtures, steel packings having been placed into the two 12-in. spaces which are left open on the Inchgarvie ends; and while yet the same circular horizontal movement round the centre of the pins is possible, both longitudinal and lateral movements are prevented. Should it therefore happen that one cantilever has to sustain the impact of a heavy gust of wind while the other is not so affected, the deflection thereby produced can take with it one end of the central girder and leave the other in its original position without putting any side stress upon the girder itself. It should be mentioned that the lower bearings at Queensferry and Fife in which the pins rest, are not bolted down to the cantilever ends, but have play sufficient to allow horizontal circular move- ment round the centre of the pins in the inter- locking arrangement above described. All expansion joints in the main structure have now been considered, with the exception of that in the cantilever end piers. At this point expansion and contraction to the amount already stated can take place longitudinally, but in no other direction. This is the only occasion where rollers are used for bearings, and the arrangement of these is clearly shown in Figs. 133 and 134. The lateral or vertical movements arising here are prevented by the following means : The steel casting A is a fixture to the under side of the extreme end of the cantilever, here in form of a box. This casting forms the head of the roller bearing, but also bears a ■side flange, which is set hard against a heavy cast-steel plate B, which is bolted down hard to the masonry, and carries a side flange similar to that of A. As the same thing is arranged on the opposite side, it is clear that lateral movement can only take place to the amount of play between A and B, which is practically nil. Again, on the top of the bottom end girder of the cantilever, outside the loaded box, a piece of steel C is laid, which touches, or nearly touches, another cast-steel plate D, let into the masonry of the pier, and bolted to it by holding-down bolts. Indepen- dent therefore of the counterpoise placed at this end, which prevents the cantilever lifting under any con- ditions of train load or fixed load, there is provision made to prevent its rising should an unusually heavy gust of storm-wind strike the end of the free cantilever, and thereby try to lift up this. This it cannot do, but the stress causes an upward deflec- tion in the fixed cantilevers within the limits of the elasticity of the metal. Neither of these two arrangements interferes with the longitudinal expansion or contraction, which are facilitated by the arrangement of rollers bet ween the castings E and F. All movements have now been considered in detail, and since they are of such vital importance, it will not be superfluous to recapitulate them here once more in toto. 1. Expansion and contraction produced by changes in temperature provided for by the sliding bedplates, by the rocking posts at one end of each central girder, and by roller bearings in the two cantilever end piers. 2. Lateral deflections, whether due to wind pressure, or to the influence of the sun’s rays, provided for (а) By the play left in the bedplates of the fixed cantilevers. (б) By the arrangement in the keyplates between lower and upper bedplates, which permit a slightly circular movement on the centre of each column, producing torsion in the same. (c) By the central vertical pins in the interlocking arrangement between ends of cantilevers and ends of central girders. All vertical deflections are taken up and resisted by the elasticity of the metal in the structure. As soon as the end posts of the cantilevers had been built, the necessary preparations were made to start with the erection of the central girders. The principle upon which this work was to proceed was the same as in the cantilevers, by overhanging, but in the absence of a fixed joint between the two, other arrangements had to be made. Both ends of the central girders required to be temporarily attached to the cantilevers until they were brought together in the centre of the span, and could there be joined up. The ends could then be released. In the first instance, heavy temporary platfoi m 1 girders had to be attached to the under side of the bottom members in cantilevers projecting over towards the central girders, some 25 ft. (See Fig. 135.) Upon these were laid cross-timbers, and a strong platform was formed upon which the first half-bay of the central girder was erected. This had to be done, however, outside, and about 6 ft. away from the end posts, because all rivets inside the end posts, and through those portions of the central girder which would have to be drawn within the end posts, required rivetting up. All these holes were countersunk, and the rivets made flush. The cups which had to re- ceive the rocking posts were meanwhile placed in position, and carefully set and levelled, and next the rocking posts, weighing nearly nine tons each, were hoisted up by special tackle and shipped into their places, and lowered into the cups or sockets. Into the tops of the rocking posts were now placed the half-balls or knuckles with flat tops, upon which the under side of the top members of the central girders would come to rest. Thus far the Inch- garvie ends. The Queensferry and Fife ends were similarly dealt with, except that no rocking posts, but only the horizontal pins, had to be placed. The shipping in and fixing of slide-blocks and vertical pins had also to be done at the same time. As soon as the half-bays of the girder on each side were built, the whole portion, weighing about 42 tons, was shifted back into its place inside the end post, and connected up and also drawn tight by a number of chains and wire ropes passed round. Heavy temporary ties were now attached at the centre of bay 6 in the top members of the canti- levers at one end, and at the centre of bay 1 in the top members of the central girders. (See Fig. 130.) These ties consisted of three layers of plate, each f in. in thickness, by 20 in. in depth. There was one such treble plate-tie to each side of a top member, or four altogether. The ends were fixed to large gusset-plates and rivetted up, but the middle joint was bolted up by special turned steel bolts, 1 in. in diameter. There were about seventy-four bolts to each joint. To the ends of the bottom members, both in cantilevers and central girders, thick cast-steel plates were fitted, leaving a wedge-shaped space between them, the wide end downwards, and this space was carefully templatecl, and steel wedges, about 9 in. v ide, two to each side, were fitted in and set up hard. (See Figs. 128 to 130, and 131.) Everything was now ready for continuing the build- ing out of the girders, and half-bay by half-bay was speedily added, some delay being caused on account of all the joints in top and bottom booms having to be rivetted before much weight was added for- ward. The top member cranes, which had by degrees made their way downhill, doing all the work since the fifth bay had been completed, as the canti- levers had by then narrowed so much that there was no room to bring the twin cranes any further, were now relieved of their heavy platforms under- neath the top member, and of other temporary appliances they carried. Thus made lighter, they were moved on the temporary plate-ties, and thence on the top booms of the central girders, where they now began to climb up the curved booms towards the centre of the span. (See Plate XIX. ) These cranes now built the whole of the work, lifting all the material out of the barges in mid-channel, except the heavy floor girders, which weighed nearly four tons each, and were hoisted by special tackle with wire ropes and steam winches set up near the ends of the cantilevers. It was not long before the Jubilee cranes, which had originally started from the tops of the Inch- garvie tower, and had proceeded, the one towards the south and the other towards the north, met face to face, the two others, which had come down from the tops of the Queensferry and Fife towers respectively, and with the putting in of the last lengths of booms, their functions practically came to an end. (See Plate IV.) Much, however, remained yet to be done, for the connections had to be made, and the making of these depended largely upon the weather, or at any rate upon the temperature. As it was not convenient to arrange the joints exactly in the centre of the girder, where they would have coin- cided with the junctions of the last pair of struts and ties, the joint was laid in each instance some b ft. nearer towards Fife and Queensferry. Hie four bays of the Inchgarvie halves were, therefore, [Feb. 28. i8co completed, and half a tie and half a strut belonging to each of the other two halves were kft incom- plete. (See Fig. 13G.) In setting out from the ends cf the cantilevers the wedges had been set in such manner as to give the bottom booms an inclination upwards, which, if no deflection had occurred, would have given the girder a camber of 12 in. The deflection, however, arising from the increasing weight overhanging, reduced this to exactly the camber prescribed — namely 3j in. The lengths of the bottom booms of the girder were fixed no as to leave at the temperature of 60 deg. still a gap of 4 in. clear between the ends. This was necessary, on account of the possibility of the temperature rising considerably above 60 deg., which in the middle of September, when the south central girder had been expected to be connected, was quite possible. For the north central girder, which was to have been connected a month later, the same gap was left for a temperature of 50 deg. only. In the top booms a somewhat larger space was left, tapering in shape from about 10 in. at top down to 6 in. at bottom of the webplates ; for here wedges had to be inserted. As it happened, however, delays occurred, and the south girder was not connected till October, and the north girder in November. The connection of these central girders was an operation of a most interesting character ; for here a greater use was made of natural forces than in any other portion of this bridge. As it was essential to have the temporary plate ties, which still held up the weight of the two halves of the central girders, fully under control, a small brick furnace, heated by oil and compressed air, in the same manner as the rivet-heating fur- naces, was built round each of the four plate ties at each end, just above the end posts, and every- thing made ready for instant lighting of the same. Arrangements were also made to draw together by hydraulic pressure the two bottom booms at the gaps in the joints in centre of girders, in order to be able to give every chance to the work being done expeditiously. The temporary connections between the booms, which, however, allowed full play to expansion and contraction, were as follows : (See Figs. 137, 138 and 139.) To the bottom flanges of the bottom booms, large and thick plates had been bolted on each side of the gap, extending over the whole width of the bot- tom flanges, and projecting to some 7 in. on each side of them, and upon these plates other plates, which reached across the gap. They were fixed on the Queensferry and Fife sides, but could move in and out at the Inchgarvie ends. F or the temporary connection there large slot-holes were provided, into which bolts l£ in. in diameter were fitted, but were not put in until the time of making good the connec- tion, the slot-holes being 4 in. long, while the holes in the plates, which were parts of the booms were simply round, of lj in. diameter. Once these bolts were driven in, the gap between the booms could not be increased, but in case of increase of tempera- ture the slots would allow the gap to decrease and prevent buckling in the booms. The arrangement is clearly shown in the illustration. The temperature had been watched for several days, and the changes in the length of the boom ends noted, and after everything was ready for making the connection, the temperature yet failed for several days to rise to within 6 deg. to 8 deg. of the 60 deg. required, and the large bolt-holes were barely half open. The application of hydraulic pressure only gave about § in., equal to 3 deg. of temperature, and there was nothing for it but to wait patiently. At last, on the afternoon of Oc- tober 10, with the sun shining brightly from the south-west, the temperature being 55 deg. gene- rally, the west boom came together near enough to give a full bolt-hole ; but the east boom wanted a quarter of an inch, in spite of all the pull that could be got out of the hydraulic rams ; so a quan- tity of waste soaked in naphtha was put into the bottom booms for about 60 ft. to either side of the gap and set on fire, and in a few moments the boom had expanded to the full amount required. All the bolts, twenty-three in number, were at once put into the holes and screwed down hand- tight,. The web-covers across the gap to each side of the booms, and the corner angles, were put on, and one side, which had been kept blind, was drilled through at once, and the covers bolted up. Feb. 28 , 1890 .] This joint having been made at the time of the highest temperature of the day, when the canti- levers and girders were of the greatest length owing to expansion, it follows that as soon as tem- perature decreased, the cantilevers and girders would shorten, and the only gap left in the bottom booms, namely at the Inehgarvie end, where the wedges were placed, would open. Had the change between the maximum temperature of day and the minimum temperature of night been considerable the wedges would thereby have been released, and, if free, would have dropped out. Precautions had, however, been taken, and had the wedges been ever so slack they could not have moved from their places. In addition to this, hydraulic cylinders had been attached to the ends of the wedges, by means of which they could when necessary be drawn out from between the plates. The change was, how- ever, only about 3 deg., and with the tremendous compression on these wedges could make but little difference. In this condition the girder was left overnight, but carefully watched, and all changes of tempera- ture and of movement in the upper booms ascer- tained and noted d nvn. At 6 a.m. 011 October 11a start was made with the drawing of the wedges first at the Queensferry end, and then at the Inehgarvie end of the girder, and they were drawn, down with little effort. (See Fig. 143 at C C.) At the same time the wedges or key-plates which closed tire top booms were placed in position and driven down hard into their places at A A. The top boom connections were somewhat different in their nature, the stresses, after connection had been made, being exactly the opposite of those in the bottom booms, namely, compressive instead of tensile. It will be remembered that the weights of the two halves of the central girders were held up by the four plate ties connecting them with the canti- levers at D D, Fig. 143. The expansions in the cantilevers, after the bottom booms were connected, would have the effect of drawing up tire centre portion of these booms in the "same way, as if, instead of a central girder, there had been a simple rope attached to these ties. On both cantilevers contracting or shrinking, the rope would have been stretched and lost some of its downward deflection or sag at B. This was precisely what occurred to the bottom booms of the girder, for the top booms were still gaping and could not prevent the further opening of the gap. A temporary sliding connection was, however, arranged in the top booms in such manner that nothing could prevent their moving nearer together or further apart with the changes in temperature. (See Figs. 140, 141, and 142.) The gaps loft between the webs of the booms, which were here thickened to 2 in., were, as before stated, from about 10 in. at top down to G in. at bottom of the web. (See Fig. 143.) The gaps at A had been templated and the key or wedge- plates made to these templates. It will now be understood that, in order that the bottom booms of the girder should retain their camber or upward deflection, it was essential that these wedge- shaped spaces should be closed at the lowest possible temperature, for, when once in their places, the top boom was closed like an arch in which the keystone had been placed. Fortunately the setting up and holding up of the girder halves during construction had given the bottom boom as much camber as was required, and it needed no assistance from the drawing of the ties, otherwise some days of delay might have occurred, for the temperature kept high and the contraction in the cantilevers Avas not sufficient to draw the ties much. The key-plates were then driven down hard and the heavy web-covers on each side were at once drilled through and bolted up. At the same time T bars of heavy section were placed at the top and bottom to form a temporary connection of the flange plates. Timber struts from side to side to keep the booms apart, and wire rope ties to hold them together, were also put on. The remaining halves of struts 4 and ties 4 of the Queensferry half of the central girder were also templated now to the required size, and put in place as soon as possible. The gaps in the top booms having now at the lowest temperature been filled by the key-plates, the effect of a rise in temperature and consequent expansion of the cantilevers would be to buckle the temporary plate-ties between central girder and cantilevers at D D, Fig. 143. As soon as this ENGINEERING. movement was felt, the bolts at the central joints of these ties (see Fig. 130, at M) were gradually withdrawn and the ties altogether detached. At the same time the furnaces were set going, and the plate-ties made so hot that, whether a rise or fall in temperature should take place, these ties could no longer restrain any movement, but would yield to either influence. With the removal of these ties the central girder entered upon its full function as a connecting link between the two canti- levers, and the south span was thereby successfully completed. A careful levelling on October 12 showed a camber of 3g in. in the girder, and no de- viation laterally from a straight line drawn between the centre of the ends of the two cantilevers. The north central girder had in the mean time been built out in a precisely similar manner, and by October 15 it was sufficiently advanced to allow a gangway 05 ft. long to be laid across. This enabled the directors of the company to walk across the bridge from end to end — the chairman of the company being actually the first person to cross the north span. By October 28 the last booms were put in, and by November 6 everything was ready to connect this girder also. The temperature on that day did not rise, however, sufficiently high to make the joint, but in the night a sudden rise took place, and by 7.30 in the morning the bottom booms were joined together for good. It now required a good fall of the temperature to get the top booms connected, for the two halves of this girder had been set less high at starting, and there was now practically no camber in the bottom booms. But the weather remained obstinate aird the temperature very high, and it was not until the morning of November 14 that the key-plates could be driven in and the final connection made. An episode, of which much has been made in the papers, occurred on this occasion, and the facts are simply as follows : After the wedges at the bottom ends had been drawn out and the key-plates driven in, a slight rise of temperature was indicated by the thermometer in the course of the morning, and orders were given to remove the bolts in the central joints of the connecting-ties and to light the fur- naces. Whether the thermometer indicated wrongly or whether the cantilevers had not had time to fully expand under the rise of temperature, or whether a decrease of the same took place it is not now possible to prove, but when only about 36 of the turned steel bolts remained in the joints, and before the furnaces could get fairly started, the plate-ties sheared the remaining bolts and parted with a bang like a shot from a 38-ton gun. Something of a shake occurred in the cantilevers which was felt at the opposite ends, and caused some little commotion among the men. No mishap occurred, however, and nothing in the way of a fall of the girders took place as stated in the papers — simply the work of the furnaces and the task of knocking out 36 bolts was saved, and the girder swung in its rockers as freely as if it had been freed in the most natural manner. And thus the Forth Bridge Avas completed — for the remaining Avork Avas simply to replace temporary connections by permanent ones, to rivet up those Avhich Avere only bolted, and do the thousand and one things Avhich ahvays remain to be done after everything is said to be finished. The thrilling portion of the story is done, and the novelist Avould wish to leave off Avith so dramatic an incident as that just told. But there are yet some details Avhich belong to the history of the bridge, and Avhich could not very Avell be left unrecorded. Rivetting. An early estimate has fixed the number of rivets in the Forth Bridge at 5,000,000, but this was evidently insufficient and the figure has risen to 6,500,000. It is, hoAvever, doubtful whether even this covers the total amount, for on the central or Inehgarvie pier, where an exact record of rivetting Avas kept, the number closed there amounts to near upon 2,700,000 alone, and a A r ery large quantity of material Avas sent across from the shops and the field Avhich had already been rivetted up, and such ri\ r ets are not included in the above total. The rivets varied as to diameter from 1) in. for the heavy tubes and the skewbacks down to f in. for the buckle-plates; and, as to length, from 11 j in. (measured Avithout the head) doAvn to 1] in. The greatest thickness of plates rivetted together Avas 9 in., and this occurred in the top junctions at the head of the vertical columns on Inehgarvie — I the least thickness aytis 1- in., in the flooring of the viaduct. The various hydraulic rivetting machines, by which about one-half of the rivetting Avas done, have already been described in the places Avhere they carried on their Avork, and need not be further enlarged ujAon here. At the commencement, ordinary furnaces fired Avith coal were used for heating, but it soon became evident that these could not be taken on the out- lying platforms owing to their weight, the weight of fuel, and last, though not least, to the danger of fire caused by hot ashes left on timber staging. Various kinds of furnaces were designed and tried, all heated by oil, and in the end the difficulty Avas solved by turning the burner of an ordinary Lucigen lamp, in a somewhat modified form, into a small furnace and setting fire to it by a piece of burning Avaste drenched in oil. This was 0 tre- mendous advantage, for these little furnaces, though made of iron and brick-lined, Aveighed little more than half a ton, and could be handled and shifted about with the greatest ease. All they required Avas a small pipe-lead to supply compressed air, and a small tank Avith oil, and a crane would pick them up and put them into any place where they Avere most handy. A boy could work them and turn out 200 rivets an hour easily, all heated evenly to a bright yelloAV heat in perfect condition for the hydraulic machines, three or four of Avhich Avere fully kept going by one of these little furnaces. They Avere taken inside the tubes, and the smoke, if care Avas taken in adjusting the burner, could not molest any one. Larger furnaces Avere set up in No. 2 shed for heating angles and tees, and they Avere very suc- cessful OAving to the regularity and evenness of the flame and the facility Avith which they could be lighted and kept up. For the hand-rivetters in the struts and lattice- girders, ordinary small forges AA r ere in use, with bellows worked by a treadle or by the hand. But here also the oil-furnaces came in usefully, for not only Avere the rivets pre-heated in the furnace if one happened to be anywhere near, but the boys contrived to make a connection somewhere with the compressed air pipes, and thus obtained a con- stant blast for their forges and saved themselves the trouble of Avorking the bellows. In places where so large an amount of timber staging Avas required, and Avhere a fire on such staging might have been accompanied by the most disastrous results to . portions of the permanent work, such furnaces as above described are of in- estimable value, for there is nothing left behind that could cause a lire after the men left Avork. As soon as the supply of air and oil are turned off all flame at once disappears, and in five minutes the inside is black and cold. The ordinary small furnaces used in the tubes and on the staging Avere about 11 in. Avide by 8 in. high and 4 ft. long on the inside, Avith tAvo doors for charging and drawing of rivets. They consumed about tAvo gallons of oil per hour, Avith Avhich they could heat 200, and on an emergency 250 rivets per hour, or even 300, if of smaller size. The actual size of this kind of furnace is hoAvever a matter regulated entirely by circumstances, and it is not possible to lay doAvn hard and fast rules for their construction. The furnaces and fittings shown in the illustrations are : A furnace for heating the ends of angle bars, tees, or narrow plates. (See Figs. 144 to 146.) An early form of oil furnace Avith grate at bottom to keep a body of glowing coal to assist combustion. This hoAvever is not necessary. (See Figs. 147 to 149.) The latest form of small rivet furnace as used on the stagings and inside the tubular members. (See Figs. 150 to 152.) Figs. 153 and 154s1ioav the disintegrator, or spray producer, the action of Avhich explains itself. In its present form it is much simplified, and if any obstruction in the small jet occurs, it is easily cleared by screAving back the mouthpiece. Temporary Work in Connection avith the Erection. If the proud boast is perfectly justified that in building the two 1710 ft. spans across the Forth, and erecting the 11,600 tons of steel massed therein, Avithout having placed a single stick of timber into the river, it is yet equally certain that this mode of erection entails an immense amount of auxiliary and temporary Avork, Avhich is both costly and waste- I ful Avith regard to time. There Avere many days 272 ancl weeks lost through waiting for crossings or junctions to be built up and completed, and although much of this may be said to be due to the novel character of the work, yet it is a point which must not be lost sight of. Elsewhere, it has been stated that owing to the general batter of the sides of the structure, and owing to all of its members being out of the perpendicular, as well as the horizontal, they had a natural tendency to either fall together, or else apart, and in both cases apt to be both out of the right direction. Thus in building out a pair of struts or ties, so soon as a length of 30 to 40 ft. had been built, it became necessary to put up temporary girders to hold them apart or keej:> them together, and a large amount of dangerous work had to be done before a further section of work could be built The members themselves, even when only bolted up, were often so stiff that hydraulic rams had to be used to force them apart or draw them together. I 11 other cases wedges of hard wood and union screws were able to deal with them. In look- ing at the illustrations and plates showing various phases of the erection, this feature will immediately attract attention, and in many cases it must be difficult for any one except those conversant with the structure to distinguish between temporary and permanent work. For reasons explained above, and easily under- stood, it was not possible to fix the wind-bracing so close up to the new work that temporary appliances could be dispensed with, and therefore an immense number of lattice-girders, some heavy, some light, had to be used to allow the permanent members to be corrected, and when corrected held in position. In the bottom members, especially near the piers, where they were some 120 ft. apart, centre to centre, the temporary girders naturally had to be very strong and heavy, but after the completion of three bays, timbers were in most cases sufficiently strong to take all resistance, and this much simpli- fied matters, for timber is both light in weight and easy to cut and shape to requirements. Thus in the bottom members alone, at every vertical tie and at every junction, the necessary corrections required ENGINEERING. money expended, but for the absolutely reliable character of this article, and for its manifold uses. In the first instance there were nearly a score of cages or hoists for the raising of men and materials to the different levels at which work was carried on, and these were going continuously day and night for several years, and there is not a single case on record of a rope having given way without having given ample warning. At first the pulleys over which the ropes passed were rather small in diameter, and the result of continuous running was that single wires commenced to give way, but with a crackling noise which soon became known to the attendant at [Fib. 28, 1890. between the girders and the ropes, the former could be raised and lowered at will and held in position until a joint with other portions of the work was made. Thus in the central towers, once they were completed, everything within the area could be suspended, and thus the internal viaduct was built in the easiest manner possible, every length in succession being held up until the girder was com- plete and able to carry itself. And thus in the same manner while building out the bottom members in cantilevers, the vertical ties and struts, and later on the wind bracings, a few wire ropes attached to the upper members, as far back as Disintegrator the placing of temporary struts and wire rope ties, and in most cases when finally fixing the horizontal wind-bracing girders, similar girders had to be placed to fix the position of the member. A repetition of this kind of work with every tie and strut, in bottom members and top members, at every vertical tie, and at every intersection, made up an amount of work of which no visible trace is left, yet which was as real in its day as any which helped to build up the mighty fabric. The Use of Wike Ropes. Of all appliances in use during the erection none have given more unmixed satisfaction than steel wire ropes. It may be considered a rash guess, though the writer at any rate has no hesitation in making it, that the list of accidents would have been doubled at least, and a great deal more time and the hoist. With the introduction of pulleys of 3 ft. 6 in. in diameter, and guide pulleys not smaller than 18 in., and having the bottom of the grooved pulleys laid with hard wood, the ropes lasted three to four times as long, that is from nine to twelve months. Even when taken off the hoists, moreover, they were quite good enough to act as guide ropes to the cages, or to support steady weights when used as pennants, or as temporary ties between the various members of the structure. All cranes used upon the erection had their chains taken off by degrees, and were supplied with wire ropes instead, which did the work more quietly and with far more safety and reliability. Still more useful were the ropes when portions of overhanging girders or other members had to be temporarily suspended from other portions already fixed. In these cases, by means of union screws attached necessary to obtain a fixed hold, held up — and if required drew up — the overhanging ends to any desired position. It is only necessary to call attention to the weight of these ropes in comparison with that of chain cables and hemp ropes of equal strength, to see at once the great advantages which the use of these ropes offered for the particular kind of work which had to be done at the bridge. Circum- Weight per Fathom. ference of Wire Rope. Wire Rope. Cable Chain. Hemp Rope. 4 in. 12 lb. 54 lb. 33 lb. 3 7 ,, 30 „ 19 ,, 2 Q3 ,, 21 „ Hi „ Feb. 28, 1890.] ENGINEERING. 273 In all cases mentioned here the wire rope had a higher breaking stress than the other two. Facility of attachment was also a very good fea- ture ; for they could be tied like an ordinary rope, or else have the end fixed round a common thimble or deadeye, and be used with shackles. Nearly all the small stages which had been passed up and down or along the members were hung by short pennants made of wire rope. Finally, they could be slung alongside or across the structure, and by means of running snatch- blocks every place made accessible to the men, or they could be used for raising material by means of single whips worked over a steam-winch barrel. The employment of wire ropes for this purpose is well shown in the large illustration on Plate X. and Plate XV. The sizes used here mainly were the 2| in. or in. diameter, the 2j in. or | in. diameter, and the 1J in. or § in. diameter were used on cranes or for single whips upon steam winches. For special purposes 3|-in. and 4-in. ropes were used, and for the service of men’s cages and hoists the 3 in. or 1 in. diameter. The tests for the latter gave a breaking stress of 26 tons to 28 tons, while nothing heavier than 3 tons in the case of material and 35 cwt. in the case of a cage full of men were ever put upon them. The Permanent Way. The internal viaduct has already been fully de- scribed in connection with the structure. The four rail-troughs in which the double line is laid are 18 in. in depth by 16 in. in width. (Fig. 155.) They are asphalted in the bottom to the level of the heel in the angle-bars, in order to make a water-tight bottom. Upon this bottom are laid transversely, about every 2 ft. 8 in. apart, blocks of teak about 5 in. square. Between these blocks the spaces are filled in with blocks of creosoted pine, all set about £ in. to 5 in. apart, and the whole is then tilled up to level with a mixture of pitch and tar and black oil, which quickly sets hard. Stiffening plates of steel, about 6 in. wide and § in. thick, are rivetted in about every 14 ft., and project about 2 in. above the teak blocks. All blocks are cut with an inward slope towards the centre of each line of about | in. to the foot. The whole mass of blocks and filling, which completely seals the lower portion of the trough, are now dressed for the reception of the longi- tudinal sleepers, which are about 12 in. by 51 in., and also of teakwood. They are cut in lengths which are multiples of the 2 ft. 8 in. distance of the transverse blocks, and are notched where the plate-stiffeners occur. Play to the extent of ^ in. to £ in. is left between sleepers lengthwise. Through the sleepers holes are bored every 2 ft. or 3 ft., and |-in. pins driven down into the blocks The sleepers are kept in position transversely by wedge-shaped blocks of teakwood. The upper faces of the long sleepers are dressed to receive the rails of “ bridge” section, the heaviest yet rolled weighing 120 lb. to the lineal yard. A section of the rail is shown in Fig. 156. The rails are joined by a horizontal fish-plate underlying the flanges, and sunk into the sleepers with a projection enter- ' ing into the hollow of the rail. The rails are screwed down by f-in. wood screws with hexagon heads. The total weight of rails, fish-plates, bolts, expansion joints, &c., for the double line of rails across the bridge and viaducts, is over 600 tons. The rail-troughs are drained of water through holes drilled into the sides every few feet at the level of the top of the tranverse blocking. In the floor of buckle-plates between the four troughs holes are placed to let the water through, these spaces being made up with asphalt mixture in such manner as to lead all the water to the outlets. The footpaths on each side of the double line are made up like ordinary pavements, on the system followed by the Seyssel Asphalt Company, the slope being such as to lead all water to the outer sides. Expansion Joints in Rails. These are all arranged on the same principle, though of different lengths. In the approach viaduct span, and at the fixed ends of the central girders, the movements are so insignificant that a very short rail-joint suffices to regulate the lateral displacement of the points due to contraction ; but, at the sliding ends of the central girders, where provision is made for a longitudinal movement of two feet, and at the ends of the fixed cantilevers, where half that length is provided, the arrange- ment is somewhat more complicated. Without going more into detail, it will suffice to say that the long rail-tongue is made an absolute fixture to the rail-trough in which its uncut end rests. Its pointed end, cut at an angle of 1 in 63, projects into the opposite trough and rests on a plate fixed therein, laying up close to the backing rail, which is bent away at an angle of 1 in 63 from the point of the tongue. The outside of the flange of the rail-tongue is cut in long steps at the same angle of 1 in 63, and is held down by draw- washers to the plate, which forms one piece with the backing- rail, but in such manner that it can slide in and out with the expansion and contraction. I11 doing so, however, by means of the sloping steps it draws the lower plate and with it the backing-rail always close up to the joint, which thus retains its position relative to the centre line of the bridge and thus keeps the gauge correct. The contrivance is very ingenious and unfailing in its action. (See Fig. 127.) The wind fence on each side of the viaduct is 4 ft. 6 in. high, and of close lattice work, and it is crowned by a handsome teak handrail of sub- stantial appearance. Painting. All plates, bars, angles, and other parts belong- ing to the superstructure, received as soon as they had passed through the shops or yards a thorough scraping with steel scrapers and steel wire brushes, and afterwards a coat of boiled linseed oil applied as hot as possible. As soon after erection upon the structure as could conveniently be done, and many cases also before they were put up, they received a coat of red lead paint, and subsequently a second coat of red lead. The paint finally decided upon for the bridge is an oxide of iron paint, of which two coats are applied over the two coats of red lead already laid. The first is called a priming coat of dark chocolate brown ; the last is a finishing coat of a bright Indian or Persian red, which, however, darkens considerably in a short time. Four different kinds of paint are used, all, however, of the same composition, if of different makers. At Fife : Craig and Rose’s. At Inchgarvie : Calley’s Torbay. At Queensferry : Carson’s. F or central girders : Wollaston’s Torbay. The above are for outside painting only, the inside of the tubular members receiving one coat of red and two coats of white lead paint. It is calculated that inside and out, the amount of surface to be painted is equal to 145 acres. Asphalting. The batter given to the sides of the structure brings with it one disadvantage, namely, that one- half of each lattice -girder flange forms with the vertical web a recess in which rain-water can lie and cause rusting. To prevent this, all places so situated that the water cannot of its own accord drain away are tilled with asphalt-concrete — that is, a mixture of asphalt, pitch, tar, and coarse gravel — to such an extent that all water will run oft’ by gravity. Where this is not possible, or would lead to too much weight being put on, holes are drilled, and the asphalt so laid that the water is drained to them and away through them. The top members in central towers, all horizontal bracing girders, and all recesses in top and bottom junctions, are done in this way. The whole of the inside of the skewbacks, except where the nuts of the foundation-bolts are situated, are also dealt with in the same manner, and the same at the bottoms of the vertical columns, the diagonal columns, and the struts in cantilevers; and in all cases pipes are fixed to lead the water to the outside. By this means it is hoped to prevent all rusting in the places where access for constant and thorough inspection, is not easily to be had. The Workmen. Taking them as a whole, it must be freely ac- knowledged that the workmen employed upon the bridge have not, to any material extent, added to the troubles and anxieties attendant upon such a work. Black sheep are found everywhere, and of the doings of such a tolerably lively account might easily be jrresented. Many of them — hundreds of them — were mere birds of passage, who arrived on the tramp, worked for a week or two, and passed on again to other parts, bringing a pair of hands with them and taking them away again, and having in the mean time made extremely little use of them except for the purpose of lifting the Saturday pay packet and wiping their mouths at the pothouse; many others also, who, too clean-shaven and too closely-cropped as to hair, vainly tried to deceive any one as to the character of the hotel they were last staying at, or to invent a plausible account of the big job which they had just left completed. The paddle-steamer, which carried the men across the river morning and night, during the day made hourly trips to the north shore and back for the ser- vice of the works and for the accommodation of visitors. Before many months had gone by it was known all over the country to every tramp that a free passage could be had for the stepping on board the boat, and the number of men who, when on the south side, were invariably asking for a job on the north side, and vice versa , increased at such an alarming rate that steps had to be taken to stop the nuisance. But apart from these, it is no exaggeration to say that no one need desire to have to do with a more civil or well-behaved lot of men, always ready to oblige, always ready to go where they were told to go, cheerfully obeying orders to change from one place to another, and, above all things, ready to help others in misfortune, not with advice but with hands and purses. Nor was there any difference in that respect on account of nationality ; Scotch, English, and Irish were about equally represented as to numbers, and though the latter furnished very few skilled hands, they were mostly very hard workers and very conscientious and reliable men. For the sinking of the caissons a number of foreign workmen were employed for a short time, and it is rather a curious coincidence that, as foreign workmen did some of the earliest work in connection with the bridge, so now again a number of foreign men are employed upon some of the last work — namely, the laying of the asphalt pave- ment along the footpaths of the permanent way, which is done under a sub-contract by the Seyssel Asphalt Company. Several strikes occurred during the building of the bridge, most of them brought about, not by the men themselves, but by organised committees in connection with various Trades Unions and their disputes with employers in other parts of Scotland. The causes were often trivial enough, such as the discharge from the works of some idle scamp with rn inordinate allowance of the gift of the gab, and whose demand to be reinstated in his dignity at twenty-two shillings per week, caused an immense amount of useless suffering to scores of his fellow- workmen, ana more still to their families, and a proportionate increase in the takings of the neigh- bouring whisky shops. The principal strike took place early in June, 1887, and was brought about through an accident, caused entirely by the carelessness of a few men. A movable stage for rivetters, consisting of two girders about 110 ft. long, disposed on either side of the vertical columns, was hung by wire ropes from winches worked by worm and wormwheel placed above. The stage served for rivetting the wind-bracings between the columns, and was made good by planking across the two girders in any place required. When one section had been done the stage was raised to the next section, and while 274 ENGINEERING. [Feb. 28, 189c. this was be ng done one of the girders fouled a piece of timber left in the girders. This was not noticed, and in spite of the resistance the men kept forcing at the handles of the winches until one of the wheels broke, and the whole stage rattled down, carrying with it some other staging on which some men were working. Two men and a boy were killed, and two more wounded, and before the real facts were known the usual agitators quickly organised a strike, demanding an increase of a penny per hour all round, equal to a rise of from 15 to 20 per cent, in their wages, on account of the dangerous nature of their work. As might have been expected the principal spouters at the meetings held during the next following few days were men who worked in the yards away from all danger, or who did not work at all, and after holding out for a week most of the strikers were glad to be allowed to come back. That accidents were frequent no one who can form an idea of the nature of the work upon such a structure need be told, but it is equally true that fully three-fourths of all more serious accidents were due entirely to what may strictly be called preventible causes. If any charge can be brought against the workmen, or at any rate a large propor- tion of their number, it is that of utter indifference or carelessness with regard to danger of causing injuries or death to one another. Not that in cases of sudden accident men would have hesitated to risk limb or life for the sake of helping. On the contrary, at such times the most heroic efforts were made to succour those in need; but in the every-day work — with that fatal familiarity that is said to breed contempt — while working on stages which could hardly be made large enough or strong enough to hold the litter of tools and rubbish which they constantly gathered, they were throwing about hammers and drifts and chisels, and pieces of wood, which in a moment were over the side, and tumbled down upon may be three or four other tiers of stag- ing, where men were engaged upon their work. Special gangs of men were organised to clear all these things away, and endless warnings and entreaties were given, but to no avail, and it needed the sight of a wounded and mangled fellow-creature, or his bloody corpse, to bring home to them the seriousness of the situation and the advisability of stooping to put down a tool instead of throwing it carelessly away. In the summer of 1883 a Sick and Accident Club was started upon the works. The member- ship was compulsory for all employed by the con- tractors, and the amount of contribution to the funds was one hour’s pay per week, the maximum contribution being 8d. per week. Members were entitled to medical advice and medicines, bandages, &c., for themselves, and medical advice for their wives and families, but no medicines, and, in addition, if unable to work, an allowance from the funds proportionate to the weekly contribution made. This aliment ranged from 9s. up to 12s. per week. The funerals of members were also paid within certain limits, and in cases of death or permanent disablement by accident or injury sus- tained on the works, grants were made to widows, wives, and children. The contractors contributed a sum of 200/. yearly to the Club, and gave a good deal of other substantial assistance. The Club proved a great boon to tire men, and more still to their wives and children, inasmuch as they got a great deal more care and attention than they otherwise would have been likely to experience. Special medical men were appointed at Dunferm- line, North Queensferry, Leith, Edinburgh, Kirk- liston, and South Queensferry. An ambulance waggon was provided, and temporary hospitals with every appliance needed in case of accident were established upon all three main centres. The amount contributed by the members of the Club in the year 1888, when the greatest number was employed, was 4096/., which, with donations, the contributions by the firm, &c., came up to 4546/. Out of this sum sick allowances were paid out to the amount of 1621/. ; accident allowances, 729/. ; funeral expenses, 143/. ; widows’ allowances, 176/. ; donation to the Royal Infirmary, 100/. ; and the rest being medical fees and other expenses. The attendances by the medical staff amounted to over 26,000 in the year. On the average 99 men were receiving aliment from the Club every week. Of accidents between July, 1883, and Christmas, 1889, when the Club ceased to exist, there had occurred 57 fatal, 106 which required removal to the infirmary in Edinburgh (in which number, however, some of the fatal accidents are included, ] the men having died after admission), and 518 minor accidents, which required, however, the attendance of a medical man. Apart from the benefits of this Club, however, the men’s welfare was looked after in every resjDect. While working in the foundations boots and waterproofs were provided for them free of charge. Later on, during the erection, they were I given thick woollen jackets, as well as overalls and waterproof suits, and although a nominal charge was made for some of these in order to check the carelessness and bad treatment of these tilings, it was rarely enforced against a careful and deserving man. Large shelters and dining rooms were provided for them, with stoves and men in charge to heat their food for them, and these were not only on deck but on the top of the central towers, at the level of the viaduct and right out near the very ends of the cantilevers. Here the men not only could take their meals in warmth and comfort, but they could retire also in case of heavy showers or sudden storms. In cases of accidents not caused by the men’s own fault, the full wages were as a rule paid by the con- tractors until the injured man was able to return to work, or unless an action was raised against the contractors. Every care was also taken and no expense was spared to make good and secure staging for the workmen, and to construct gangways and roomy staircases to all places where work was carried on. The wages paid to all classes of workmen were as a whole rather above the average, and as by far the greatest amount of outside work was done by the piece, a skilful and steady workman was enabled to make double and treble his ordinary time wages if he applied his abilities and energies in the right direction. Some curious aspects of the labour question deve- loped themselves in connection with piecework. The hand-rivetters worked invariably in squads of four, namely, two rivetters, one holder-up, and one rivet-heater, generally a boy or lad. Now it is easy to see that the skill or the want of it in the last functionary was of great influence upon the number of rivets put in during a day’s work, and con- sequently a sharp handy lad was worth a good wage, and as a rule he knew it. Rivetters are not generally very steady, but often lose a day or two, in which case one or more of the squad are liable to enforced idleness. After some little discussion among themselves, these rivet-heating boys stood out for a fixed minimum sum, 20s. to 24s. per week, and this had to be paid whether the squad worked or not. This did not of course affect the employers, for in piecework the head man of the squad was paid so much per 100 rivets, and he had to settle with the other members of his squad. In another sense it is said the boy is father to the man ; here the boy was master of several men. The wages were paid weekly. The number of men employed varied somewhat with the nature of the work to be done, and naturally also with the seasons, as in some instances it was next to impossible to work during the night. In the spring of 1887 the number had risen to 3200, and rose to over 4100 in September of the same year. After the lifting platforms were up to full height in the central towers the number fell again during the winter months to about 2900, but rose again as the summer advanced. The largest number employed at one time was 4600. From January, 1889, the numbers gradually decreased, and in January, 1890, the average was 1200, and in February, 1000. A large proportion of these hands are platelayers working upon the permanent way, and painters and their labourers. The removal of the staging round the piers and the landing jetties, and the disposal of the plant, as well as the restora- tion of the ground occupied by the workshops and yards, for agricultural purposes, will occupy a goodly number of hands for some months to come yet. The Railway Connections. The railway works now in course of construction, and more or less directly connected with the Forth Bridge, are extensive and important as regards the amount of heavy work they entail. Of these only two lines are being constructed by the Forth Bridge Railway Company, the remainder being done by the North British Railway Company. The two lines are the south approach and the north approach rail- ways, the former extending from the south arches of the bridge to a junction with the North British Railway at Dalmeny, the latter from the north arches of the bridge to a junction with the North British Railway at Inverkeithing. The engineers for the approach railways are Messrs. Sir John Fowler and Baker, and the con- tractors Messrs. W. Arrol and Co. The further works are : On the south side : 1. A line from Dalmeny Junction in a more direct line to a junction with the North British Railway at Corstorphine Station, outside Edin- burgh. Total length, 6 miles. Engineer, Mr. James Carswell. Contractor, Mr. W. Arrol. 2. A line from a point between Dalmeny Junction and the Forth Bridge, to a junction with the North British Railway at Winchburgh. Length, 41 miles. Engineer and contractor the same as for Corstor- phine line. On the north side : 3. A line from Inverkeithing to Burntisland to join the ordinary route from Edinburgh to Dundee, via Granton and Burntisland. Total length, 7 miles 3 chains. Engineer, Mr. W. R. Galbraith. Con- tractors, Messrs. John Waddel and Sons. 4. Widening and doubling of a line from Inver- keithing to Townhill Junction, both on the North British system. Length, 5 miles 24 chains. Engi- neer, Mr. James Carswell. Contractors, Messrs. G. and R. Cousin. 5. A new loop line from Cowdenbeath to Kelty, both on the North British system. Length, 2 miles 6 chains. Engineer, Mr. W. R. Galbraith. Con- tractors, Messrs. Charles Brand and Son. 6. Widening and doubling of a line from Kelty to Mawcarse, North British system. Length, 10 miles 3 chains. Engineer, Mr. James Carswell. Contractor, Mr. John Best. 7. A line from Mawcarse through Glen Farg, to a junction with the Bridge of Earn station, North British system. Engineer, Mr. W. R. Galbraith. Contractors, Messrs. Charles Brand and Son. A glance at the map of Scotland will show that through these new lines the North British Railway obtains access to both the east and west of the northern parts. To Dundee and Aberdeen, via Inverkeithing, Burntisland and the Tay Bridge. To Perth and the districts served by the Highland Railway, via Inverkeithing, Kinross, Glen Farg, and Bridge of Earn. The line from the Forth Bridge to Winchburgh opens a direct route to and from Glasgow and the west coast without touch- ing Edinburgh. The following is the estimated cost of connecting railways now under construction on the North British system : South of the F orth : Dalmeny to Winchburg ,, to Corstorphine ... North of the Forth: Inverkeithing to Burntisland New lines, and widening and doubling existing lines between Inverkeithing and Mawcarse, also Glen Farg line from Marcarse to Bridge of Earn £ 56.000 78.000 213,000 435,000 Total estimated cost ... ... £,774,000 The following Table of comparative distances between Edinburgh and four towns north of the Forth, both by Caledonian and North British, may be of interest: — Length in Miles. North British. Cale- donian. Edinburgh to Aberdeen, via Forth and Tay Bridges ... Edinburgh to Dundee, via 130 159 Forth and Tay Bridges ... Edinburgh to Perth, via Forth 59 90 Bridge Edinburgh to Montrose, via 48 69 Forth and Tay Bridges ... 90 123 It is not improbable that arrangements can be made to get the following results as regards train service between London and the North. London to Perth, 9f hours. London to Dundee, 10^ hours. London to Aberdeen, 12j hours. Feb. 28. 1890.] ENGINEERING. 275 The South Approach Railway. This line has a total length of 5S chains, and passes through a cutting about 20 ft. on the average in depth, through soil and clay, and strata of free- stone, intermixed with coal and shale. At about 10 chains from the bridge the new Forth Bridge Station is situated. At 45 chains the line to Winchburgh branches off to the west with a sharp curve. The building of the Forth Bridge Station, and the widening of cutting, bridges, and embankments not at first contemplated, will bring up the total cost to about 20,000?. The contract will probably not be finished until the end of April. The North Approach Railway. This line is nearly two miles in length, and com- mences with an embankment at the north end of the bridge. The embankment is 34 ft. in depth at the abutment of the masonry arches, and continues for a length of 14 chains, when cutting No. 1 com- mences. This cutting is through whinstone, and is over GOO yards long, with an average height of 80 ft. The work here was commenced by driving a toplift from both ends at about 40 ft. above formations, and at the same time bottom gullets from the south end and the north end. The material excavated was run down an incline, worked by gravity in the ordinary way, and de- posited to form No. 2 bank. The excavation made in the topdift proved the rock to be of such a nature that an open cutting at the great depth would not have been compatible with safety to the traffic, and it was decided to form a covered way for the portions already excavated and to tunnel the remainder. Accordingly, shafts were sunk in two places, and headings were driven from them in each direction. The tunnelled portions are lined with side- walls of roughly dressed whinstone and rubble backing, while the roof is of brick. The covered way has side walls and roof both of whinstone masonry. Starting from the south end of this cutting there are 189 yards of covered way, 229 yards of tunnel, and 154 yards of covered way, at the end of which the cutting terminates and bank No. 2 commences. This is 11 chains in length, and is followed by a cutting through whin- stone 11 chains in length and, on the average, 50 ft. in depth. Another embankment follows, gradually deepening and leading to a viaduct crossing the North British Railway and the public high road, and by another bank the outskirts of Inverkeithing are reached. The viaduct consists of masonry abutments in the form of eliptical arches of 75 ft. span at either end and four spans of steel girders of 100 ft. span each. The girders rest on masonry piers set at an angle of 25 deg. to the centre line, and the whole viaduct is on a curve of 40 chains radius with a gradient of 1 in 70. At the north abutment of this viaduct the bank is 85 ft. in height, but, situated on rising ground, rapidly falls away. At H miles from starting another cutting through whinstone commences, this extending for 6 chains, followed by a tunnel 378 yards in length under the town of Inverkeithing. Finally the line terminates in a. junction with the North British Railway at Inverkeithing. The last-mentioned tunnel is also on a curve of 40 chains radius with a gradient of 1 in 70, and was excavated by means of headings driven from each end. The enlargement to full size was principally made from the south end of the tunnel, as the material was required at that end for the filling up of the banks. This tunnel is lined with masonry side walls, and a brick roof. Apart from the heavy cutting and tunnelling work, the greatest difficulty in this contract was caused by a bog through which bank No. 2 had to be carried. After some quantity of spoil had been tipped from the north end of No. 1 cutting, the weight of this material commenced to force up the ground in front, and this to such an extent as to displace the public high-road running to the south- west side of the bank, carrying this road some GO ft. out of its course and altering the gradients materially. There was at one time a fear that it would displace the North British Railway line be- tween North Queensferry and Inverkeithing as well, but fortunately it stopped short of this. There is in this bank an excess of 69,000 cubic yards over and above the estimated quantity of 11E.600 cubic yards, and to obtain the necessary quantity of spoil the east side of No. 2 cutting was enlarged to the necessary extent. Geologists will have it that this is the site of an extinct volcano, but it will probably be best to leave this question to be settled by geologists. In the excavation of tunnels and cutting, pneu- matic drills were generally used with good results. The explosives used were both dynamite and ordi- nary blasting powder. The total rock excavation amounted to 341,500 cubic yards in the solid. The filling in the banks is as follows: Bank No. 1 33,400 cubic yards. No. 2 115,000 ,, (original estimate) ,, 69,000 ,, (excess) No. 3 198,100 Masonry 24, 850 , , Ballast 13,350 ,, Filling 1,000 Total 455,300 cubic yards. The total weight of steelwork in the viaduct and road bridges is 460 tons for the former and 190 tons for the latter — total, 650 tons. The whole north approach line, from the abut- ment of the bridge to Inverkeithing, is on a gradient of 1 in 70, except at one point, where it is level for about 100 yards. The sum for this contract was 88,678 ?., increased through extra work by 18,0001., or a total of 106,6781. — equal to something over 56,0001. per mile. A new station has been built at Inverkeithing. At present there is no station between this and the Forth Bridge Station on the south side. The writer wishes to express his indebtedness to Mr. Louis Neville, the contractors’ engineer for the approach railways, who furnished the above parti- culars. Weight of the Superstructure. The subjoined tabular statement will give some idea of the amount of steel distributed over the main supports. Weight of a fixed cantilever: 5441 tons. ,, ,, free cantilever: 5375 tons. ,, ,, 1710 ft. span: 11,571 tons 10 cwt. ,, ,, cantilever bridge per foot run: 9 tons 11 cwt. Table No. XII. on the next page shows the quantities of steel erected and bolted up and rivetted during the years 1887, 1888, and 1889, month by month. These quantities apply to the three main piers of the cantilever bridge only. The total cost of the foundations of the Forth Bridge may be roughly put down as nearing 800,0001.; and in connection witli this expenditure ! it is necessary to mention the name of Mr. P. W. Meik, who acted as resident engineer for, and as | representative of, Messrs. Sir John Fowler and j Baker from the commencement in 1883 until the completion of the masonry piers in 1886, and of whose unfailing tact and courtesy his many friends retain the liveliest remembrance. Another name should be added here, that of Mr. William Gray, who from start to finish had charge of all excavation and masonry work, besides other duties of the most multifarious character, and of whom it may be truly said that, day or j night, early or late, no one would ever call upon him and find him unwilling to do what was wanted. The total expenditure by the F orth Bridge Company upon construction has been as follows. | The figures are approximate amounts as far as ' expenditure year by year is concerned, but the total amounts are correct and authentic. For half-year ending cd bp £ 3 3 -g December 31, 1882 7000 IZl ^ 5 0 <3 0 ^ June 30, 1883 December 31, 1883 42,800 57,000 Ph ib 40 K 3 June 30, 1884 119,000 ® O^ 3 December 31, 1884 218,200 2+3 oT . June 30, 1885 231,000 O cj December 31, 1885 216,000 0 ^ J une 30, 1886 188,000 S .0 g to December 31, 1886 253,500 •3 g 0 0 CO £ g ® June 30, 1887 December 31, 1887 240.000 243.000 S -3 June 30, 1888 195,700 P O $4 O O O P-, O December 31, 1888 218,000 5 » s c June 30, 1889 182,000 December 31, 1889 138,000 h 9H CO t-M EH Total 2,549,200 Add to this the amount expended in connection with Sir Thomas Bcuch’s suspension bridge (including all parlia- mentary expenses) ... ... ... 250,000 2,799,200 Parliamentary expenses in connection with cantilever bridge, engineering ex- penses, interest during construction, &c. 378,006 Total expenditure to January 1, 1890 3,177,206 It is estimated that a further sum of 50, 000 J. will be required to complete the structure, the painting included. The sale of plant is expected to realise fully 120 , 000 ?. For the erection alone of the Fife, Inchgarvie, and Queensferry Piers, that is, everything on top of the circular granite piers which may be strictly called the superstructure, the amount of wages paid including salaries of officials in charge of the piers, amounted up to November 30, 1889, to a total sum of 344,810?. ; the total amount of steel put up and rivetted up to that date being 50,064 tons. The cost of labour for that work is therefore 6?. 17s. 9d. per ton erected and rivetted up. The total amount of wages and salaries paid on the works up to January 1, 1890, was 1,045,000?. The Forth Bridge Railway Company. The agreements between the four companies which guarantee the interest on capital, provide that the directorate of the Forth Bridge Railway Com- pany should consist of the chairman and vice-chair- man of each of the four interested companies, and of two directors elected by the general body of share- holders. The chair of the Forth Bridge directorate is held in rotation by the four chairmen of the guaranteeing companies, the term of office being twelve months. The representation at present is a:; follows : — Mr. M. W. Thompson, chairman, and Mr. W. Unwin Heygate, Midland Railway Company. Lord Colville, of Culross, and Lord Hindlip, Great Northern Railway Company. Mr. John Dent-Dent, deputy chairman, and Sir Matthew White Ridley, Bart., North - Eastern Railway Company. The Marquis of Tweeddale and the Earl of Elgin and Kincardine, North British Railway Company. TABLE No. XI. — Quantities of Steel used in Main Spans. Description of Parts. Fife. Inchgarvie. Queensferry. Total. Tons Cwt. Tons Cwt. Tons Cwt. Tons Cwt. 3 Central towers, including bedplates ... 4815 16 7036 4815 16 16,667 12 6 Cantilevers 1 fixed 1 free 2 free 1 fixed 1 free Bay 1 4235 4 4312 12 4235 4 12,783 2 2626 2 2658 12 2(326 2 7910 16 1764 6 1724 16 1764 6 5253 8 ,, 4 1034 3 1009 16 1034 3 3078 2 ,, 5 665 18 620 4 665 18 1952 ,, 6 490 2 423 12 490 2 1403 16 2 Central girders ... 410 15 821 10 410 15 1643 Rocking-posts and steel castings 51 9 51 9 51 9 154 7 Ladders in tubular members 36 40 36 112 Totals 16,129 15 18,698 11 16,129 15 50,958 1 276 ENGINEERING. TABLE No. XII. — Progress op the Erection of the Superstructure of tiie Forth Bridge, 1887 to 1889. Month. 1887. 1 SC 8 . 1889, Erected and Bolted up. Ri vetted. Erected and Bolted up. Rivetted. Erected and Bolted up. Rivetted. Tons. Tons. Tons. Tons. Tons. Tons. J anuary ... 793 521 1045 1080 1159 1922 February ... 652 716 1055 1149 1126 1647 March 922 817 653 742 1098 1499 April 1242 984 1703 1382 1061 1565 May 1122 819 1910 1316 1556 1991 June 1099 500 2351 1760 1047 1595 July 1180 973 1923 1341 593 1080 August 1151 1045 1929 1742 449 891 September 1050 879 2089 2104 897 906 October ... 1285 938 1638 2397 626 799 November 1561 1235 873 1402 265 515 December... 959 1112 1598 1948 111 449 13,016 10,536 18,767 18,379 9988 14,859 TABLE No. XIII. — Summary of Progress in Erecting Superstructure of the Forth Bridge. — Erected and Bolted up. Rivetted. Up to the January 1 , 1886, there had been put together and rivetted . Tons. Tons. 512 512 During the year 1880 ... 8284 6227 „ „ 1887 13,016 10,536 ,, ,, 18S8 18,767 18,379 ,, ,, 1889 9988 14,859 Total to January 1, 1890 50,567 50,513 There remained, therefore, on January 1, 18D0, still to do— 391 tons to erect and bolt up, 445 tons to rivet. Mr. Spencer Brunton and Mr. James Hall Renton, elected by the shareholders. The secretary of the company is Mr. G. B. Wieland, who is also secretary of the North British Railway Company. The engineers to the company are Sir John Fowler, K.C.M.G., C.E., and Mr. Benjamin Baker, C.E. The contractors for the bridge are : — Sir Thomas S. Tancred, Bart. ; Mr. W. Arrol ; Mr. T. H. Falkiner ; and Mr. Joseph Phillips. The contractors for the south and north approach railways are: Mr. W. Arrol ; Mr. T. H. Falkiner ; and Mr. Joseph Phillips. On the staff of Messrs. Sir John Fowler and Baker were the following : Mr. Allen Stewart ; Mr. P. W. Meik, resident engineer from 18S3 to 1886 ; Mr. F. E. Cooper, resident engineer from 1886 to 1890 ; and a number of assistants. On the contractor’s staff were : Mr. Thomas Scott, manager ; Mr. W. Westhofen, who was specially engaged on Hie works at Inchgarvie ; Mr. A. S. Biggart, in charge of drawing offices, shops and yards ; and a number of others far too nume- rous to mention. The Visitors. Their name is simply legion, for from beginning to end there has been an extraordinary amount of interest shown in this work by all classes of society. [Feb. 28, 1890. From the visit of their Royal Highnesses the Prince and Princess of Wales, August 23, 1884, down to the present day, hardly a week has passed without bringing some person of rank or distinc- tion. Dom Pedro of Brazil, the Kings of Saxony and of Belgium, and the Shah of Shahs, head this list, which includes, without exaggeration at any rate one-tenth of all people distinguished by rank or by scientific or social attainments. As in most other matters ladies were to the fore, pluckily climbing into every nook and corner where anything interesting might be seen or learned, up the hoists and down the stairs and ladders, and frequently leaving the members of the so-called stronger sex far behind. It is needless to say that under such circumstances the duties of those called upon to guide the fair visitors were of the most agreeable. The Preliminary Tests. On January 21, 1880, two trains entered upon the bridge, side by side from the south end, and composed as follows : — Each train had two locomo- tives of 72 tons each at the head, followed by 50 waggons weighing fully 13 tons 10 cwt. each, and one engine at the rear of 72 tons. Total weight of each train, 900 tons ; total weight on bridge, 1800 tons ; total length of train when close-buffered, 998 ft. 6 in. ; the same, when open or loose- buffered, 1040 ft. The train was moved slowly until the two engines in front were three-quarters through the central girder connecting Inchgarvie with Queensferry, the rear engine being about the centre of the Queens- ferry Tower. This is considered the most unfavour- able load for the Queensferry north cantilever. In that position the following observations were made : The vertical columns of the central tower in Queens- ferry were drawn north to the extent of 1 $ in. The end of the Queensferry north cantilever deflected 5 in., the end of the Inchgarvie south cantilever deflected 1$ in., the end of the Queens- ferry south cantilever (at that time not fully loaded by nearly 200 tons) rose to the full amount of play existing, namely, of an inch. The Queensferry south cantilever in itself took an upward deflection of about 1 £ in. The train then moved forward until the two front engines of the trains were three-quarters through the north central girder, the most unfavourable condition of loading for the Inchgarvie north canti- lever. In this position the vertical columns of the Inchgarvie central tower were drawn north to the extent of I 4 - in., while the Fife central tower was drawn \ in. to the south. The vertical downward deflection of the end of the Inchgarvie north canti- lever was 6 | in., and the same for the end of the Fife south cantilever was 2f in., while the end of the Inchgarvie south cantilever rose to the extent of 3b in. It is not necessary in the face of further trials by the Board of Trade, to say more than that all these movements were well within the calculated amounts. TIIE ENGINEERS AND CONTRACTORS OF TIIE FORTH BRIDGE. Our work of describing the Forth Bridge would be incomplete without suitable notices of the engi- neers and contractors upon whom the responsibility of its construction rested. As we have seen, Messrs. Harrison and Barlow took no part in this work ; having finally approved the design, they gave Messrs. Fowler and Baker the task of its execu- tion. It is of these gentlemen, therefore, as well as of Messrs. Tancred, Arrol, Falkiner, and Phillips, and of M. Coiseau, who completed the pneumatic foundation, we shall attempt to give such notices as will convey an idea of their respective careers during the course of which they acquired the experience necessary for carrying out this great work. We have been led to deal with the biography of Sir John Fowler at great length, because his history is the history of the most important period of the profession, and dates back for more than half a century. Silt John Fowler, K.C.M.G. The period over which Sir John Fowler’s career extends practically coincides with that of the profes- sion of modern engineering. In saying this we do not forget the illustrious men who preceded him, such as Telford, Trevithick, Watt, Smeaton, and Rennie. But these all flourished before the manufacture of iron, and the tools for working it, had so far pro- gressed that it was readily available for every-day use. Many of them executed splendid works in brick and stone, works which will uphold their reputations for centuries, and others of them were capital mechanics. But it was not then practicable to use iron, and particularly wrought iron, for large structural purposes. It is worth while to recall a few instances in exemplification of this fact which is often forgotten. The first flour mill which had iron wheels and shafting was erected by Rennie in 1788. The first iron bridge was designed by French- Italian engineers in 1755, and was attempted to be constructed at Lyons, but the founders proved unable to cast it. In 1777 a cast-iron bridge of 100 ft. span was erected at Coalbrookdale, and this was followed in 1796 by one over the Wear. This latter had been constructed to the directions of the celebrated Tom Paine for a different site. A third bridge was erected by Telford over the Severn about the same date, and he constructed four other cast- iron bridges before the century terminated. Rennie’s first iron bridge was opened in 1803 at Boston. It is thus shown that the employment of iron on a large scale during the eighteenth century was prac- tically unknown. In the early part of the nine- teenth century, cast-iron was largely used for bridges, for canal aqueducts, for locks, and for dozens of other purposes, only to be supplanted in its turn by wrought iron. When this metal could be obtained cheaply and abundantly, engineering science entered upon a new phase of its existence, and the world commenced to progress at a speed hitherto undreamed of. It was under conditions such as these that the subject of our sketch entered his professional career. He was born in 1817 at Wadsley Hall, Shef- field, the residence of his father, Mr. John Fowler, and when his general education was completed, the boy, at the age of seventeen, became a pupil of Mr. Feb. 28, 1890.] J. T. Leather, the well-known hydraulic engineer. Here he had ample facilities for obtaining a thorough training in several branches of his calling, and in all cases his experience was gained in works of very considerable magnitude. Yorkshire enjoys the advantage of possessing a great number of diverse industries, and it was very early in the field as a manufacturing district. From its coal, iron, steel, and woollen trades, in addition to its farming and shipping pursuits, great wealth was rapidly accumulated after the close of the bad times follow- ing the Napoleonic wars. The entire world was then the customer of England, and the shrewd people of the Hidings managed to secure a large share of the trade. The county thus was able to find employment for many engineers, and among them Mr. Leather took a leading position. He executed many works for the supply of water, notably those of Sheffield. The Stockton and Darlington line was opened when Mr. Fowler was only eight years of age, and the Liverpool and Manchester Railway when he was but thirteen. He had not completed his pupilage before the rush, which eventuated in the railway mania, commenced. When Mr. Fowler left Mr. Leather he went straight into the railway world, finding in the office of Mr. .T. U. Rastrick a very wide field. He be- came his chief assistant in the preparation of the drawings and contracts for several railways ; among these was the line from London to Brighton. To this latter Mr. Fowler gave great attention, and there is scarcely a bridge or viaduct which was not personally worked out by him. After two years spent in London, lie returned to Mr. Leather, and became responsible resident engineer of the Stockton and Hartlepool Railway. After it was completed he remained two years as engineer, general manager, and locomotive superintendent of that and the Clarence Railway. It is no wonder that these en- gineers of the old school can turn from one subject to another with so much versatility when we con- sider what an education they had. Instead of having professors to fill them with ready -digested knowledge, like the young men of the present day, they were moved from one position of responsi- bility to another, and their intellects were hardened and invigorated by constant work. Every step they took was an experiment on a working scale, and every fact they learned was imprinted on their memories by the toil and trouble it had cost. On the termination of this engagement, Mr. Fowler visited, at the invitation of Sir John Mac- neil, several railways in the neighbourhood of Glasgow, and gave evidence before Parliamentary committees regarding them. He commenced an independent career at the age of twenty-six, and as we have already seen, he started with a broad and solid foundation of experience, suitable for the towering reputation which was to be built upon it. Several important railways were then being pro- moted from Sheffield, such as the Sheffield and Lin- colnshire, the Great Grimsby, the New Holland, the East Lincolnshire, and others, and of these Mr. Fowler became the chief engineer, conducting them through Parliament and carrying them out. It was in the year 1843 that this work was commenced, and before it was completed the railway mania attained its full proportions. The history of that movement has often been written ; how fortunes were made and ruined in a day ; how men lost their reason in a moment both from good and evil tidings, and how the capital subscribed during those years, often for the wildest undertakings, almost rivalled the days of the South Sea Bubble. We have no intention of redrawing the picture, but the following incident will show at what high pressure engineers were expected to work in those days. One night when Mr. Fowler was asleep in his father’s house, a carriage and four drove up to the door, and the household was aroused by loud knocking. On descending Mr. Fowler found that a prominent promoter of railways had called with the purpose of inducing him to undertake the engi- neering of a new railway from Leeds to Glasgow, and that as an earnest he had brought an order for 20,000k, as a preliminary payment on account of the survey expenses. It then only wanted a very few weeks (quite inadequate for the purpose) before the day of depositing tire plans. Mr. Fowler had the prudence to decline the offer, and the car- riage of the disappointed promoter went thundering away, the occupant little dreaming how many years would elapse before his plan would be carried out. It was only men of iron constitution that came un- scathed through those times, and many an engineer ENGINEERING. who would have risen to eminence, had he been able to husband his strength, threw away his life in furthering the schemes of the promoters. When the autumn approached, and the fatal thirtieth of November hove in sight, surveys and drawings had to be made at the greatest possible speed. The hours of the night were annexed — sometimes all of them — to supplement those of the day, while meals had to be taken when they could, or not at all. The deposit of the plans brought rest to the rank and file, but the chief responsible engineer had then to enter upon the still more trying work of preparing for, and attending, Parliamentary committees. Often he had to appear before three or more committees in one day, pitting his wits against those of half a dozen counsel, backed by eminent opposing engineers. The engineer could not imitate the members of the bar, and choose in what cases he would appear and which he would neglect, taking his fees for all. Indeed, it is said that Charles Austin, the leader of the bar in the committees of the House of Commons, had once been engaged to appear before twenty-two committees in one day, and as it was impossible for him to attend to them all, he showed his impar- tiality by reading his newspaper and attending to none. The progress of committee work was watched with keenest interest by men who did not know an embankment from a cutting, but who took ad- vantage of every turn of the fight to manipulate the share market. They listened to the evidence of the engineer and sold and bought accordingly. If he tripped in his advocacy of a measure, or was foiled in his attack on a hostile scheme, they hurried to anticipate the effect on the money market. Mr. Fowler once met an acquaintance rushing along the corridor of the House in the wildest excitement, and when he stopped him to learn the cause, the man exclaimed, “Don’t detain me! Robert Stephenson has broken down in his attack, and I am off to buy a thousand Great Northerns.” Every- body gambled in shares, and like all gamblers their choice was determined by the merest trifles. If a line were fortunate, promoters would endeavour to appropriate as much of its name as they could for other lines, in the hope that their particular venture would gain by the association. As an instance Mr. Fowler’s Great Grimsby Railway was at a premium, and consequently the name of Great Grimsby was brought in quite irrespective of geographical facts. This was done to such an extent that the then chair- man of committee (Lord Devon) exclaimed “ What! Great Grimsby again ! Go it, Great Grimsby !” Mr. Fowler had now attained a position which necessitated his permanent residence in the metro- polis, and work of all kinds flowed in to him. It is quite beyond the limits of our space to notice, much less to describe, one-half of the matters about which he was consulted or the works lie carried out. Amongst them we may mention the following : The Oxford, Worcester, and the Wol- verhampton Railways; the Severn Valley Railway ; the London, Tilbury, and Southend Railway (in conjunction with Mr. Bidder) ; the Liverpool Central Station, the Northern and Western Railway of Ire- land, the railways of New South Wales and India, the Sheffield and Glasgow Water Works, the Metropolitan Inner Circle Railway, the St. John’s Wood Railway, the Hammersmith Railway, the Highgate and Midland Railway, the Victoria Bridge and Pimlico Railway, the Glasgow Union and City Railway, and St. Enoch’s Station, the Millwall Docks, the Channel Ferry, and many others. Mr. Fowler’s reputation with the general public of this generation rests to a great degree on his con- struction of the Metropolitan Railways. These were so far out of the common that every Londoner, and a great many people out of London, took the greatest interest in them. The most extravagant anticipations were indulged in as to the relief they would afford to the streets if they were ever completed. But the difficulties were so enormous that many, if not most, people imagined that they could not be overcome. The directors were constantly being told that they had embarked their own money and that of the shareholders in an impos- sible enterprise. Engineers of eminence assured them that they could never make the railway, that if they made it they could not work it, and if they worked it nobody would travel by it. Such a catalogue of impossibilities was enough to appal any man, and often faith in the enterprise fell to a low ebb. At such times they would say to Mr. Fowler, “ We depend upon you, and as long as I you tell us you have confidence we shall go on.” 2 77 It was an awful load to put on the shoulders of a man who had already sufficient to attend to in combating the physical difficulties of the affair. The troubles with vestries and their engineers and officials, with owners of property and their agents, were for many years during the construction of the first section of the Metropolitan Railway tedious and wearying to the last degree. All these were finally overcome, and the line was opened. So far from there being a difficulty in inducing people to travel by it, the traffic astonished the most expe- rienced railway experts. The general public did not take the view laughingly expressed by Lord Palmerston when asked by Mr. Fowler to perform the opening ceremony, “ I intend to keep above ground as long as I can.” Of course they grumbled at the ventilation, or rather the want of it, and re- proached the engineers f< >r not improving it. Origi- nally, when a junction with other railways was not intended, a special hot-water engine without a live fire, and therefore not passing the products of com- bustion into the air of the tunnel, was proposed. Experiments were made witli an engine so con- structed, but before it was perfected it was decided to make a junction with the Great Western Rail- way, and, therefore, locomotives of ordinary con- struction had to be admitted on the system. It was ni 18f)J that the first Act was obtained for a line 2j miles in length from Edgware-road to Battle Bridge, King’s Cross. Plans for extensions westward to Paddington, and eastward to the City, were at once prepared, and the financial support of the Great Western Railway was secured. After a severe fight, the Act for the extended railway was obtained, the plans providing for tunnels and stations large enough to accommodate the broad gauge Great Western trains, as well as the narrow gauge local trains which it was designed to run. There was, however, a difficulty in raising the capital, and it was not till the spring of 18150 that the contract was made, and the works commenced. In 1861 powers were obtained for extending the Metropolitan Railway to Moorgate-street ; and in 1864, for constructing the eastern and western extensions to Tower Hill and Brompton respec- tively. In 1863 a Lords’ Committee decided that it would be desirable to complete an inner circuit of railway that should abut upon, if it did not actually join, nearly all the principal termini in the metropolis, commencing with the extension in an easterly and southerly direction of the Metro- politan Railway, from Finsbury Circus at the one end, and in a westerly and southerly direction from Paddington at the other, and connecting the ex- tremities of those lines by a line on the north side of the Thames. The inner circle was the direct outcome of this recommendation. The construction of the so-called Underground Railway was the means of solving a great many problems which at the time presented much diffi- culty. Questions which are now fully understood, and which would be undertaken by contractors as a mere matter of course, then were of very grave importance, and had not only to be exhaustively discussed, but to be attacked with the greatest caution. It was not then known what precautions were necessary to insure the safety of valuable buildings near to the excavations ; how to timber cuttings securely and keep them clear of water without drawing the sand from under the founda- tions of adjoining houses ; how to undermine walls, and, if necessary, to carry the railway under houses and within a few inches of the kitchen floors with- out pulling anything down ; how to drive tunnels ; to divert sewers over and under the railway, to keep up the numerous gas and water mains, and to maintain the road traffic when the railway was being carried on underneath ; and finally, how to construct the covered way so that buildings of any height and weight might be erected over the rail- way without risk of subsequent injury from settle- ment or vibration. All these points Mr. Benjamin Baker declared, in a paper read some five years ago before the Institution of Civil Engineers, received much anxious discussion and criticism before they were decided upon. Such questions as the admis- sible stress on brick arches loaded on one haunch only, the extent to which expansion and contrac- tion of iron girdei’s would affect buildings carried by them, the ability of made ground to resist the lateral thrust of arches, and a multitude of similar problems, had to be dealt with tentatively at first, and with increased boldness as experience was gained. As an instance of the confidence which experience gives we may cite the following : doubts 278 ENGINEERING. [Feb. 28, 1890. entertained by the engineers as to the behaviour of a compound brick and iron structure led to a timber front being put to the Edgware-road Station, where it rested on a 49-ft. span girder ; yet in 1865, when the extension to Moorgate was executed, no hesita- tion was felt in trusting an elaborate brick and ashlar face wall, weighing 1300 tons, to a continuous girder 135 ft. in length. It would be tedious and unprofitable to attempt to give a detailed account of the construction of the Inner Circle line, since the lessons taught by it have long ago been incorporated into the routine of engineering practice. It will ever remain a monu- ment to the skill of the engineers concerned in its construction. Of these Mr. Fowler is responsible for the greater part, as shown by the annexed Table, which gives the lengths and percentages due to each. Inner Circle Railway. Mr. John Fowler, engineer Mr. Edward Wilson, ,, Mr. Francis Brady, ,, Mr. Joseph Tomlinson, .Tun. Messrs, llawkshaw and Barry Length Executed, miles ch. 11 20 0 27 0 28 0 35 0 58 Per- centages. 86 2 1 13 8 100 The main lines of the Metropolitan and Metro- politan District Railways being complete, Mr. Fowler carried out the lines in connection with them, including the St. John’s Wood Railway, the Hammersmith line, the West Brompton line, and others. His original plan, brought before the Parliamentary Committee, included an outer circle as well as an inner circle. Unfortunately, the Committee was induced to reject the outer circle on the faith of certain promises made by another line. These promises have not been practically fulfilled, and the immense advantage of being able to conduct all through passenger, goods and mineral traffic by a perfect and comprehensive scheme around London was lost for ever. Although somewhat out i if chronological order, we may here refer to another underground railway, of which Mr. J. H. Greathead is the engineer. This railway — the City and Southwark Subway — is not opened at the time of writing, but it is rapidly approaching completion, and great hopes are entertained that it will be the pioneer of a new system of railways which will prove as great a convenience as those already in existence in the metropolis. The ventilation difficulty is avoided entirely by the device of using electric power for the propulsion of trains, while the expensive work of diverting sewers and pipes, underpinning build- ings, disappropriating tenants, and buying property, is evaded by keeping the tunnels at a very low level. As the line follows, for the most part, the streets, there is little to pay for land, and the chief expense is that of construction. A Bill now before Parliament contemplates the creation of a second railway of this kind from Bayswater to King William-street, E.C., Sir John Fowler, Mr. B. Baker, and Mr. J. H. Greathead being the engineers. If it is made it will prove the greatest advantage to Londoners. Mr. Fowler was elected President of the Insti- tution of Civil Engineers for the year 1866, and took the chair for the first time in that capacity on January 9. His presidential address was devoted to the subject of the education of an engineer, and was so important and valuable that it has been reprinted and distributed extensively, notably by the Government of India to the engineers in its employment. He began by calling attention to the fact that the exclusive position hitherto held by the English engineers was not likely to continue, since both in France and Germany great efforts were being made to educate young men both theo- retically and practically for this profession. Hence, although this was greatly to the advantage of engi- neering science, it behoved the Institution to see that the distinguished and leading position which had been so well maintained by their great prede- cessors, should not be lowered by those who came after them. After a short enumeration of the nature of the works and duties which fell to the lot of a civil engineer, he proceeded to enforce the necessity of a full comprehension of the nature and qualites of materials, and the proper adapta- tion of the design to the materials in which it was to be carried out. He asserted his conviction that it was most important that the early preparation and subsequent study of an engineer should be as extensive as possible, and should em- brace every branch of professional practice. The sound knowledge and experience thus acquired would add greatly to his efficiency and value in any special branch. For the railway engi- neer there was required a thorough knowledge of surveying and earthworks, the capacity to design bridges, earthworks, and tunnels, and a knowledge of the effect of floods and drainage. To this should be added some knowledge of archi- tecture, and a taste for appropriate decoration. The dock and harbour engineer required, he said, much of the general knowledge of the railway engineer, with a vast amount of special know- ledge. This included the laws which govern the tide, the set and speed of currents, their scour and silting ; also questions relating to the trade to be accommodated, and the methods of dealing with the goods. He would also be required to be cog- nisant of such matters as harbours of refuge, piers, landing stages, lighthouses, forts, and hydraulic appliances. The water works engineer, in addition to his general qualifications, had to be familiar with the means of collecting information about rainfall, the method of gauging streams, the excavation of reservoirs, conduits, weirs, tunnels, and aqueducts. He must also be competent to superintend and design sewerage works. The mechanical engineer, the speaker continued, dealt with the most varied and numerous subjects of all the branches of engi- neering. He must understand the laws of motion, of heat, of liquids, and gases ; he must be familiar witli the strength of materials and the friction of surfaces. On railways he was responsible for the machine tools, engines, and locomotives. For docks he had to design the machinery for working the gates, the sluices, and the cranes. For water works he produced the pumping engines, sluices, valves, stop-cocks, &c. And so on through the entire series of works in which mechanism is em- ployed. The mining engineer needed, in addition to a knowledge of railway and mechanical engineer- ing, the information requisite for sinking shafts, draining workings, excavating and raising minerals, and preparing them for market. Mr. Fowler then turned to the preparation required by a civil engineer to enable him to perform his work efficiently. This he classed under four heads : (1) General instruction, or a liberal education ; (2) special education as a pre- paration for technical knowledge ; (3) technical knowledge ; (4) preparation for conducting prac- tical works. He supposed a boy to start at four- teen years of age with a strong constitution, con- siderable energy and perseverance, and a fair education, together with a mechanical bias. The period from fourteen to eighteen should be devoted, lie said, to a special education, including mathematics, natural philosophy, surveying, draw- ing, chemistry, mineralogy, geology, strength of materials, mechanical motions, and the principles of hydraulics. To these must be added considerable progress in French and German, even at the sacri- fice of classical studies and pure mathematics. At the age of eighteen, assuming the boy to have fair abilities and more than average perseverance, three courses were open. He might be placed with a civil engineer for four or five years’ pupilage, or in a mechanical workshop, or he might lie sent to one of the universities. The choice would depend on the taste of the boy, the means of his parents, and other circumstances. If he. followed either of the first two courses it would be necessary for him to con- tinue his studies in mathematics, science, and foreign languages at the same time. If the latter course were adopted, the drudgery of learning to survey, to draw, and the like, must be passed through first. With a clever hard-working boy the most advan- tageous course might be to send him, from seventeen to eighteen, into a good workshop, then for three years for a university course, and finally into an engineer’s office for his pupilage. This, of course, would require a boy of special ability and determi- nation to render it a successful course. The office chosen for the pupilage to be passed in ought to lie well organised and not too large ; the engineer should bo a comparatively young and rising man, and be accustomed to take pupils, who should be few in number, and bear some proportion to the number and extent of the works in usual course of construction under the engineer’s direction. Here the pupil ceased to be a boy, and his future success or failure could no longer be directed by others, but depended upon his own abilities and industry. Mr. Fowler also laid stress on the fact that the whole duties of the engineer were not comprised in the mere accomplishing of the objects entertained by his employers. It was his duty, he held, to advise those who consulted him whether the under- taking was one that would repay the expenditure which must be made upon it. The engineer was not merely a man of technical skill engaged to bridge the difficulties of capitalists, as a servant carries out the orders of his master ; on the con- trary, he was a member of an honourable and noble profession which could not lend itself to enter- prises which did not give fair promise of being beneficial to the world, and to the advancement of civilisation. In 1870 Mr. Fowler took part in a commission sent to Norway to examine the railways there. As is well known Norway has built a great length of railway which was constructed at a very small cost and is worked very cheaply. Now, at the date men- tioned the Indian government were undecided whether to adhere to the broad gauge of 5 ft. 6 in., which had been adopted for the trunk lines, or to introduce a narrower gauge for the less important railways. A commission composed of General Strachey, Colonel Dickens, Mr. Rendel (now Sir A. Meadows Rendel), and Mr. Fowler, was, therefore, sent to Norway, for the purpose of acquiring information as to what gauge should be adopted in India, assuming that it was decided that a narrow gauge should in certain cases be laid down. The commission was received and accom- panied by Mr. Carl Piliil, the experienced engineer of the Government, who had carried out all the railways in Norway. They travelled over the Dovre Fjld by carriole, passing over the ground on which a railway has since been constructed, and were thus able to see the nature of the works which would have to be carried out. The Norwegian lines are 3 ft. 6 in. gauge, and the rails and engines are both very light, the speed being usually quite slow. Mr. Fowler considered this gauge narrow enough, and the engines too light for economy. His colleagues, however, took a different view, and recommended 2 ft. 9 in. as the i:>roper gauge for India. Two reports, therefore, were made, one by Mr. Fowler recommending 3 ft. 6 in. gauge, and one by the other members of the commission, recom- mending 2 ft. 9 in. The final decision of Govern- ment was between the two, but much nearer Mr. Fowler’s opinion, viz. — a metre, or 3 ft. 3i in. It was understood that the question referred to the Commissioners was not whether narrow-gauge railways should be adopted in India or not, but, supposing a narrow gauge to be adopted, what gauge should it be. Mr. Fowler, from his long experience of the evil on the Great Western Railway, had very strong objections to breaks of gauge except when unavoidable. He would never permit an exceptional gauge in a link, or a possible link line, nor for short branches where exceptional plant would neutralise all saving. He considered that an ex- ceptional gauge should be confined to a district of country where break of gauge is unimportant by reason of non-interchange of traffic, and even then lie preferred to adopt a light railway on the standard gauge, except under very peculiar circumstances, which must be very rare indeed, when the narrow gauge would have some special advantages. Last winter (1888-89) Sir John Fowler had the opportunity of verifying by actual inspection on the sjnot, the opinion lie had formed as to the rail- way policy of India, and it is well known that he has expressed himself as having had his former conclusions strongly confirmed by his Indian visit. Sir John visited Darjeeling to see the work- ing of the 2 ft. 6 in. gauge mountain railway, ascending 8000 ft. by gradients of 1 in 27. This curious little railway has been laid on the fine road made to Darjeeling, and, being saved all ex- penses except that of permanent way, it is not surprising that a good dividend is earned, notwith- standing the fact that the engines can only draw less than twice their own weight up the incline. I 11 this case the gauge and everything else are suited to the traffic, but unless the same circumstances were found the system could not be applied else- where with advantage. Sir John was naturally much consulted, both professionally and otherwise, in India by the authorities on the subject of railways, docks, and water works, and was received everywhere with great distinction. His general impressions of India and its resources were of the most favourable character. Feb. 28, 1890.] One of the most interesting chapters in Mr. Fowler’s career is that connected with Egypt. He went there, in the first instance, in search of health ; and the connection thus accidentally formed lasted as long as Ismail Pacha remained in power. As is well known, that enterprising Sovereign threw himself heart and soul into the material improvement of the country. He had unlimited credit in the money markets of western Europe, and he aimed at restoring Egypt to its ancient position as one of the chief producing countries of the world. He brought about a wide extension of the irrigating system of the Delta, in order that crops might follow each other inde- pendently of the season of the year; he introduced sugar plantations and factories in Upper Egypt on a most extensive scale; he built several railways, and projected one southwards to Khartoum, which, if completed, would have been the key to Central Africa. He entered upon every scheme witli the greatest ardour, and no sooner were the plans com- pleted than he urged the giving out of the contracts and the commencement of the work. I11 Mr. Fowler the Khedive found the very man he wanted — one whose ability was only equalled by his rectitude. National prosperity, however, is not to be founded by railways, docks and canals alone. Its basis lies in good government and the just administration of wise laws ; but it is not our business to go into the politics of Egypt further than to explain the condition of affairs when Mr. Fowler came in contact with them. He landed in Egypt at the close of 1868. At this time the Suez Canal was within a year of its com- pletion, and it was natural that Mr. Fowler should hurry to see it, even before fulfilling the avowed object of his visit of exploring the antiquities of the country. The trip was made under very favour- able circumstances, the party including M. de Lesseps, hi. Voisin, the Duke of Sutherland, Sir Richard Owen, General Marshall, the Marquis of Stafford, Mr. W. H. Russell, and others. The works from Ismailia to Port Said, and the harbour works at Port Said, were well advanced, but between Ismailia and Suez nearly one-third, or twenty- five million cubic yards of excavation, remained to be executed. The survey occupied three days, and included the whole length of the canal, everything being explained by M. do Lesseps with tlie greatest kindness, and the various points being discussed without reserve. At the request of the editor of the Times Mr. Fowler addressed a long letter to that journal giving a full account of the state of the works and criticising the prospects of the company. This letter appeared on F ebruary 18, 1869, and was made the text of a leading article which pronounced it to be a fair and final summary of the subject by an English engineer of the highest eminence and repute. In the spring of 1869 the Prince and Princess of Wales visited Egypt. When about to make the journey up the Nile the Prince invited Mr. Fowler and Professor Owen to join the party, which was embarked on five steamers and dalia- beahs. Nothing could be pleasanter than to make the excursion under such conditions, as every ar- rangement was made for the Royal party to see the objects of interest in the country, both ancient and modern. Of course Mr. Fowler had to pay the usual penalty of fame, and to be prepared to suggest the probable methods employed by the Egyptians in raising large stones for the pyramids and temples, and in cutting and polishing the greenstone and diorite statues. At Thebes his engineering re- sources were severely tried by the Prince’s cross- examination as to the manner in which the colossal statue of Rameses IT., weighing 888 tons, was brought from the quarry near Assouan to its present position at Memnonium on the plain of Thebes. The excursion proved to be most enjoyable. Before Mr. Fowler returned home he had several interviews with the Khedive, explaining to him his views concerning the Suez Canal, the irri- gation schemes, and many other matters in which Ismail Pacha was interested. The outcome of this was that he accepted the position of consulting engineer to the Khedive and the Egyptian Govern- ment, a post which lie held for eight years — that is, until the abdication of that ruler. The office involved yearly journeys to Egypt, the first being in the latter part of 1871, and required Mr. Fowler to personally investigate all the great undertakings then in hand. The most important matter presented to him for solution was the projected Soudan Rail- way. It is needless to say that, although com- ENGINEERING. menced, and 150 miles constructed, it was never carried out, or recent Egyptian history would have been greatly changed, while thousands of British soldiers and millions of money would have been saved. Mr. Fowler, before deciding between the two possible routes by the Nile Valley and by Souakim- Berber, had long interviews with General Gordon, and also with the governors and other persons acquainted with the country to be traversed. The Nile Valley was ultimately chosen, and the decision ratified by the Khedive and his ministers. The surveys were commenced at once, and when com- pleted the Khedive, with characteristic promptitude, instructed Mr. Fowler to obtain a contract for the work. This was accordingly done, and on February 11, 1875, the works were commenced at Wady Haifa with great ceremony in the presence of Mr. Fowler, the governor of the province, the Cadi, and other notables, bullocks being slaughtered as part of the religious observances. The abandonment of the railway, and all the disasters which followed it were keenly felt by Mr. Fowler, who fully believed that had Khartoum been thus connected with Cairo the turbulent native tribes could have been overawed, and a great economy would have been effected in the long run. Unfortunately it is not given to man to read the future, and when matters went wrong in Egypt the expense of the railway seemed too great for the resources of the country Although this railway was not completed, and has passed for the moment out of public notice, yet it is a matter of certainty that sooner or later it will be constructed. The eyes of nearly all European nations are concentrated on Africa, and many are striving to secure a firmer foot- hold on the continent with a view to gaining a share of the future trade which is anticipated. It is certain that when Egypt attains the position which is sure to follow upon a few years of good government, there will be a revival of the old ambi- tions, and she will turn her attention southward, with that craving for extended sovereignty which is the characteristic of 'all healthy communities. It will, therefore, be interesting to give a few facts regarding the route, length, and cost of the line which must be made if the flood of Arab invasion is to be permanently dammed. Sir John Fowler always held the opinion that our difficulties in the Soudan came from the undecided attitude we took up. The native tribes could not be neutral ; they were obliged to side either with the English or the Mahdi. But the former declared that they had not come to stay ; they came to rescue Gordon, and when that was done they would retire, and leave the entire population “to stew in their own juice.” This promised to be so highly flavoured with Mahomedan vengeance that the tribes were obliged to cast in their lot with the successor of the Prophet, and fight against the invaders. In the days of Ismail Pacha the Soudan was ruled by the shadow of the authority which existed at Cairo, and Sir John Fowler holds that the same conditions would recur if the railway were completed. The southern terminus of the line was to be at Metammeh, 011 the left bank of the Nile, imme- diately opjmsite Shendy, 16 deg. 14 min. N. lati- tude, and 32 deg. 25 min. E. longitude. Shendy is equidistant between Berber and Khartoum, and about 99^ miles from each. It is moreover the con- verging locality for the camel routes from Khartoum and the White Nile district, from Hamdal, Souakim, and the Red Sea, and from Aboo Kharraz and tire Blue Nile. There is good navigation between Berber and Khartoum for ten months in the year, and the obstructions which exist in the low-water channel would not be difficult to remove or lessen. The northern or Egyptian end of the line was fixed at Wady Haifa, at the second cataract. Com- mencing at the foot of the cataract on the right bank of the river, the line followed the general course of the stream as far as Kohe, this side being chosen to avoid the drift sand from the Nubian desert. At Kobe the line crossed the Nile, and then followed the right bank as far as Dabbe. Here the Nile makes a long detour, and consequently the projected line struck across the Bahiuda desert to its terminus. The following are the lengths ; Miles. Wady Haifa to Kohe ... ICO Kohi to Ambukol ... ... ... ... 216 Ambukol to Shendy ... ... ... ... 176 279 The line was one of easy construction, with no works of magnitude except the Nile crossing. When practicable it kept to the villages and cultivated lands on the banks, but sometimes it took an in- land course amongst the mountains to avoid expen- sive works, and sometimes it traversed deserts to cut off bends of the river. The gauge was fixed at 3 ft. 6 in., the same as the Norwegian railways, but with a heavier rail of 50 lb. to the yard ; the maxi- mum gradient was 1 in 50, and the minimum radius of curvature 500 ft. The cost, including stations, sidings, quays or landing places, rolling stock, work- shops, and all expenses required to complete the line ready for traffic, was estimated at four millions sterling, or 7240?. a mile. Of this amount five- eighths would have been spent abroad and three- eighths in Egypt. It will be noticed that the railway was to start at the second cataract, some 550 miles, as the crow flies, from Cairo. The Nile forms a natural road- way between the two for the entire distance, except for some three miles at Assouan, where the first cataract occurs. To enable steamers and dahabeahs to pass from the lower to the upper level of this cataract, Mr. Fowler conceived the idea of a ship incline, and in company with Sir William (now Lord) Armstrong and Mr. Rendel he went to the site. The necessary surveys, examinations, and estimates were made, and on the return to Cairo Sir W. Armstrong offered to undertake the work, and his proposals were approved. But like many other projects of that time in Egypt, the plan was frustrated by the interference of jealous foreign rivals, and nothing was done. The plan contemplated the construction on the right bank of the canal of a ship railway 3 kilo- metres in length, commencing at the bottom of the cataract in the river channel, about 5 kilometres south of Assouan, and terminating at the top of the cataract in the harbour of Shellal. The boats to be transferred were to be floated upon a cradle con- structed to run upon the railway, and to be hauled over land by hydraulic engines of 400 horse-power, placed near the centre of the railway. The water to work the engines was to be pumped at a high pressure by a pair of large stream wheels carried upon pontoons, and driven by one of the smaller rapids at the lower end of the cataract. The total length to be traversed over land by the boats was 2950 metres at low Nile, and 2300 metres at high Nile. The estimate of the cost of the incline with machinery, workshops, wharves, and all expenses required to complete it ready for traffic, was 200 , 000 /, One of the first matters claiming Mr. Fowler’s attention on undertaking the duties of consulting engineer was the organisation of the existing rail- ways, and to this lie devoted much time on his first official visit in 1871. As a preliminary he employed Mr. D. K. Clark to obtain for him full details of the rolling stock and plant. With this information before him, Mr. Fowler was able to advise great changes in the direction of simplicity and economy, most of which were carried out. The management had previously been of a most unsatisfactory condition. In the year 1869 the expenses per train mile amounted to 7s., of which the locomotive power figured for os. 5d. Many other items were needlessly high, and were increased by the practice of keeping duplicate sets of accounts, more or less imperfect, in French and Arabic. Mr. Fowler considered that the expenses could be well cut down to 4s. 6d. per mile, or 36 per cent, of the earnings. This small percentage was due to the very high traffic charges, particularly on the transit railway which conveyed the P. and O. Company’s passengers across the isthmus ; on this line first-class passengers were charged 4fd. per mile, and second-class 2|d. ; accelerated goods were charged 4jd. per ton, and unaccelerated Id. per ton per mile. In the same year visits were made to Upper Egypt to examine irrigation works and sluices, and to Suez to determine matters connected with the docks there. M. Duport, on Mr. Fowler’s recom- mendation, was appointed engineer in charge of the new Alexandra Docks, a post which he filled in a highly satisfactory manner till the completion of the works. In the following year, 1872, the most important matter for consideration was the sugar plantations and factories of the Khedive. Already several millions sterling had been spent upon them with but poor returns, and the time had come when some alteration in working must be decided upon. 280 ENGINEERING [Feb. 28, 1890. To aid him in forming his judgment, Mr. Fowler secured the valuable assistance of Mr. (now Sir Frederick) Bramwell and Dr. Letheby. The result was that reports of the most exhaustive character were presented to the Khedive, and formed a valuable guide for all future operators. The Khedive, however, was too sanguine, and the works were established too rapidly and on too extensive a scale. Possibly the climate was also not quite suitable for sugar cultivation. The broad result was a very serious loss of money to the Government. During the course of the investigation into the conditions of the sugar estates, several interesting facts, worthy of being placed on permanent record, were demonstrated. It was found that the soil of Egypt, which, of course, is entirely Nile deposit, consists of a large amount of fine sand, mixed with an unctuous clay, in the form of minutely divided double silicates of alumina and iron, together with fine oxides of iron, alumina, potash, alkaline sili- cates, soluble silica, and a fair proportion of car- bonates of lime and magnesia. The soil is in such a minute state of subdivision that it readily yields its most important constituents (silica, phosphoric acid, and potash) to the growing crops. For the cultivation of sugar it is necessary to equalise the excess of potash by the applica- tion to the land of more phosphoric acid, and to make up for the deficiency of nitrogen by the addition of ammonia. Analyses were also made on another occasion of the Nile water to determine whether it had, when used for irrigation purposes, any manurial value beyond that due to the sus- pended mud. The samples were taken about the middle of the months of June, July, August, Sep- tember, and October. It was found that in each case the water contained a considerable quantity of nitrogenous matter in the form of actual ammonia, as well as ammonia derivable from organic matter. The proportion of actual ammonia was largest in July and smallest in August. The organic ammonia was smallest in the August sample and largest in September. Taking the whole of the ammonia derivable from 100,000 parts of water, the quantity ranged from .0114 parts in the August sample to .0271 in the sample collected in June. These are remarkably large proportions when we consider that the Nile does not receive anything in the nature of sewage or ordinary town drainage, for they are largely in excess of the pro- portions found in the River Thames at Hampton. The properties of soluble saline matters in the Nile water range from 13.443 parts per 100,000 in Oc- tober to 18.8 parts in June. The chief ingredients in these saline matters are the carbonates and sul- phates of lime and magnesia, but there is also a notable quantity of soda and potassa, as well as a trace of phosphoric acid. The sedimentary matters in the several samples taken amounted to 6.915 parts per 100,000 of water in June, and to 149.157 parts in August ; and the proportions of organic matter in the deposit ranged from .829 parts to 18.414 parts. The results show that the water of the Nile is remarkably rich in fertilising matters, for not only does the water contain in solution a notable quantity of ammonia, nitrogenous organic matter, and the soluble silicates of potassa and soda, as well as a trace of phosphoric and nitric acids, but it also contains in suspension a large amount of sedimentary matters which are charged with phosphates and alkaline silicates. The most important Egyptian question submitted to Mr. Fowler was that of irrigation. Upon this depends to a great extent the fertility of Lower Egypt, for although the annual inundations can be depended upon to give the land one thorough water- ing, there are many crops that need to be watered several times and at different seasons of the year from that at which the flood comes. Immense irrigation works were constructed by Mehemet Ali, with canals running through the delta and the land on either side of it. For a considerable part of the year these canals served their purpose fairly well, but at the period of low Nile many of them became useless because they were at too high a level. This does not arise from any error of the designers, but from the fact that the barrage, which was built to maintain a minimum depth of water in the river, did not prove capable of resisting the required head. Hence it was necessary to allow the river to fall below the proposed level. Under these con- ditions Mr. Fowler was instructed (1) to prepare alternative plans for placing all the cultivated and cultivable lands of Lower Egypt in a position to be irrigated at any time of the year without pumping ; (2) to devise an improved means of introducing flood water several times during high Nile upon any required lands on the left bank of the Nile, and of dis- charging itat pleasure without interference with other lands ; (3) to prepare a scheme for the construction of a ship canal between Alexandria and Cairo. Mr. Fowler proposed as alternative projects under the first head ; (1) a high level canal on the right bank of the Nile ; (2) a high level canal on the left bank of the canal ; (3) the completion of the present barrage or the construction of a new one. None of these proposals were then carried out, but during the past few years, under the superintendence of Colonel Sir Scott Moncrieff, the barrage has been repaired to such an extent that it will hold the water up to 3 metres, instead of 4.5 metres, as contemplated by Mr. Fowler. The methods employed in the repair of the barrage followed the lines laid down by Mr. Fowler, but were on a less extensive scale, as the pressure to be resisted was less, and there was greater difficulty in obtaining money than during Ismail Pacha’s time. The deficiency of head is made good by pumping into the higher canals. The second undertaking required a canal starting very high up the Nile, and following the course of the Balir Yousuf, but it presented no features of special engineering interest, and was not attempted. The third, the ship canal, was a subject in which Ismail Pacha took the greatest interest. He found that the effect of the Suez Canal was to divert the traffic from the capital, and to take the stream of passengers through the country without adding any- thing to its wealth or importance. He, therefore, conceived the idea of making Cairo into a sea- port, with easy access to the Mediterranean. Mr. Fowler worked out a combined irrigation and ship canal from the Mediterranean to the Red Sea, by way of Cairo. This canal would have been a formidable rival to the Suez Canal, in so much as the dues derivable from the irrigation water would have enabled the tolls on ships to have been reduced to a very low figure. I 11 the negotiations which sub- sequently took place with the Suez Canal Company, the possibility of the second canal being made, served as a powerful lever in the hands of the English party. Although so many of Mr. Fowler’s Egyptian schemes were not carried out, we must not regard them as wasted effort. For thousands of years Egypt has been the prey of conquerors of many races and creeds. Probably for the first time in her history she is in the hands of a power which has no selfish aims, and thinks solely of the good of the inhabitants. Under such conditions she must prosper, and the time is certain to come when many of the ambitious schemes of her late ruler will become possible of realisation. At that moment the reports and drawings of Mr. Fowler will be turned to as the key of the plans to be adopted. Space does not permit us to particularise all the great works in Egypt with which Mr. Fowlerwascon- cernecl, such as the construction of steamers for the Khedive, surveys for a railway to Harrar, and many others. For nine years he made periodical visits to the country, and became greatly interested in its fortunes. The connection was broken, however, when Ismail Pacha was made to abdicate, and a new era of economy was introduced. Egyptian credit was almost exhausted, and what little was left was destroyed by the revolt of Arabi Pacha. A few years later (1885) the Queen, on the recom- mendation of the Marquis of Salisbury, created Mr. Fowler Knight Commander of the Order of St. Michael and St. George “for important services and guidance to Her Majesty’s Government in con- nection with Egypt.” A curious example of the way that the engineer may be useful in averting political troubles is found in one of the incidents of Mr. Fowler’s career. The Italian premier, M. Minghetti, had disagreed with Garibaldi on the question of the rectification of the Tiber. The popular patriot was powerful at the time in Italy, and wielded an influence which the Government did not care to have exercised against themselves. At the same time they did not feel able to accept his views on the particular question before them. Mr. Fowler was at that time at Cairo on one of his Egyptian visits, and it was decided to submit the matter to him. He was accordingly summoned to Rome, and was fortunately able to reconcile the differences of the two parties, to the great relief of the Government. We now come to the Forth Bridge, the best known of all the works with which Sir J ohn F owler has been associated, and one which at the present moment is engaging the attention both of the general public and of engineering experts in all parts of the world. Sir John lays no claim to be the sole author of the design which was the joint outcome of four minds, all bent on discovering the best and cheapest means for cai’rying a railway over the Firth of Forth. Most people will remember that when the Tay Bridge was destroyed, preparations were being made, and were actually commenced, for bridging the Forth. Sir Thomas Bouch had designed a suspension bridge for' the purpose, and an Act of Parliament had been obtained authorising its construction. The failure at the Tay at once threw doubts upon the safety of the most ambitious project, and the works were stopped. Subsequent investigation showed that the proposed bridge could not have been a satisfactory one. A bridge across the Forth offered so much advantage to the railway companies forming the east coast route to Scotland that, after two years, the idea was revived. On February 18, 1881, the four great railway companies concerned, the Great Northern, the North-Eastern, the Midland, and the North British, wrote to their consulting engineers — Mr. T. Harrison, Mr. W. H. Barlow, and Mr. John Fowler, associated with Mr. B. Baker — propounding two questions for their joint opinions. They were asked to consider the feasibility of building a bridge for railway purposes across the Forth, and, assuming the feasibility to be proved, what description of bridge would lie most desirable to adopt. The matter involved so large an expenditure and contained so many novel issues that it needed to be approached with the greatest possible care. It was fairly well known how many types of bridge there were to select from for such a site; — these were (1) Mr. Bouch’s original design; (2) a stiffened suspension bridge; (3) a second form of stiffened suspension bridge ; (4) a cantilever bridge. Calculations of weight and cost were made for each type of bridge and were discussed by Messrs. Harrison, Barlow, Fowler, and Baker, with the general result that the cantilever type was chosen. A report was made to the railway companies on May 4, 1881, embodying the result of the deliberations, and pointing out that the cantilever principle offered a cheaper and better solution of the problem than any other. The report did nut enter into the details of construction; indeed it could not be said to give even the broad features, other than those which are involved in the use of the cantilever. These still remained to be elaborated in council, and it was only by united discussion that the original plan developed into the final design. Although the type of the bridge is very ancient there were many features in it which were open to consideration, and to differences of opinion, and at each meeting of the engineers new ideas were propounded, and novel methods of over- coming difficulties were mooted. After most elabo- rate investigations and calculations the structure gradually, by a process of evolution or development, assumed its present form. The design being settled ancl the execution decided upon by the associated railway companies, the carrying out of the work was entrusted to Mr. Fowler, in conjunction with his partner, Mr. Ben- jamin Baker. The Parliamentary fight had been exceedingly stubborn, for great interests were at stake. Hitherto the London and North-Western and the Caledonian companies have enjoyed a great advantage in carrying the Scotch traffic to Perth and the High- lands, in consequence of the east coast traffic having to traverse the circuit from Edinburgh via Larbert and Stirling to Perth. But when the bridge is opened this advantage will disappear. A very strong hybrid semi-public committee was appointed, with Lord Stanley, of Preston, the present Governor of Canada, as the chairman. Engineering evi- dence was brought forward to condemn the struc- ture, and every possible description of hostile evidence for shipping interests was adduced against it, and made the most of by eminent counsel, who both in speeches and cross-examination strove to the utmost to prejudice the undertaking. But at the close of the case the committee were unanimous in favour of the Bill, only stipulat- ing that the Board of Trade should maintain a general inspection of the works during construction. It was finally arranged at the suggestion of Mr. Fowler that the inspectors should report to Parlia- ment every three months as to the progress of the bridge, and the quality of the materials and workman- Feb. 28, 1890.] ENGINEERING. 281 ship. These reports, made by General Hutchinson and Major Mar indin, have appeared regularly in our columns, and all have spoken in the highest praise of the way in which the undertaking was being carried out. Sir John Fowler and Mr. Baker have kept a personal and continuous control over the entire opera- tion of building the bridge, and have superintended the series of processes, from the rolling of the plates to the closing of the rivets. They have further employed several distinct staffs of assistants for the purposes of (1) surveying and foundation work ; (2) for working drawings ; (3) for inspecting plates at the mills ; (4) for inspecting the rivetting ; and (5) for the fitting and erecting. Mr. Alan Stewart was chief of the staff in Westminster, where all the detailed drawings and calculations were made. The resident engineer was Mr. Cooper, who entered Mr. Fowler’s office in 1863, and has remained there ever since. Mr. Tuit, Mr. Lilliquist, and Mr. Carey, and other engineers of exceptional ability were also on the engineers’ staff. The con- tractors were selected on account of their previous experience. Mr. Phillips had had great experience in bridge building ; Sir Thomas Tancred and Mr. Falkiner in large contracts and the organisation of labour ; and Mr. Arrol had shown on previous occasions remarkable ability and resources. In the early days Mr. Phillips took an active part, but in the preparation and erection of the steel Mr. Arrol took the leading position, and he was ably seconded by Mr. Biggart, Mr. Moir, Mr. Westhofen, Mr. Harris, Mr. Scott, Mr. Bakewell, and others. Having brought this series of sketches of inci- dents in tire career of Sir John Fowler up to the commencement of the Forth Bridge, we do not pro- pose to carry it further. In the columns of this issue will be found full details of the design and construction of that magnificent work. The bridge, however, has not monopolised the whole of Sir John Fowler’s time and attention ; he has been connected with many other important works in the meantime, besides fulfilling his standing engage- ments. Sir John became consulting engineer, on the death of Mi'. Brunei, to the Great Western Railway, and besides this and many smaller under- takings, he is consulting engineer to the Great Northern, the Brighton, and Highland railways. Mr. Benjamin Baker. The career of Sir John Fowler, which we have endeavoured to sketch in the foregoing columns, may be regarded as a contribution to the early history of the profession rather than as a biographical notice. When Mr. Baker began his career, Sir John Fowler had been actively en- gaged in a variety of important work for more than twenty years. The great pioneers of the pro- fession had, most of them, either passed away, or had retired from active service, their work having been continued by those who had served with them, benefiting by their experience, and enlarging it with their own. Engineering had, in fact, been reduced to a science that replaced the more or less experimental pursuit which had occu- pied the previous generation, and the foundation had been securely laid for the development which to-day distinguishes the profession throughout the world. But it was not alone the early engineers who bequeathed a rich inheritance of experience to their successors. Industry and applied science in every direction which could be useful to constructive work were progressing steadily and with rapidity. Especially this was the case witli the manufacture of iron, which rendered undertakings easy that would have been impossible to the older engineers, who had little at their disposal except timber, stone, and brick. And later, when, in the march of pro- gress, iron had to give way to steel, engineers were enabled to undertake and carry out successfully, undertakings which their immediate predecessors could not seriously consider for want of the proper materials. In the atmosphere of enthusiasm that naturally surrounds the successful completion of so vast a structure as the Forth Bridge, one is too apt to forget, in presence of the stupendous work, how much is due to the great army of workers who have laboured — blindly in some cases — since the beginning of the century, and to ascribe some of the credit to its creators which is really due to the general advance in mechanical science charac- teristic of the age. As Lord Brassey said on a recent public occasion, ‘ ‘ I like to remember that if my father had not laboured I should not be Lord Brassey. ” In his many public utterances on the sub- ject of the Forth Bridge Mr. Baker has always brought this fact prominently before his audience, Speaking at Southampton seven years ago, he said: “The merit of the design, if any, will be found, not in the novelty of the principles underlying it, but in the resolute application of well-tested mechanical laws and experimental results to the somewhat difficult problem offered by the construc- tion of so large a bridge across so exposed an estuary as the Firth of Forth.” At Montreal, two years later, when the works were in full swing, he said : “ If I were to pretend that the designing and building of the Forth Bridge was not a source of present and future anxiety to all concerned, no engineer of experience would believe me. Where no precedent exists the successful engineer is he who makes the fewest mistakes.” At Newcastle, last year, when delivering the workmen’s lecture of the British Association to an audience of 4000 men, he remarked that the success of the work was due as much to the individual and collective pluck and ingenuity of the workmen as to the scientific labours and organisation of the engineers and con- tractors ; and as President of the Mechanical Science Section of the Association at Aberdeen, he said : “1 have no doubt that as able and enter- prising engineers existed prior to the age of steam and steel as exist now, and their work was as beneficial to mankind, though different in direc- tion.” It is quite clear, therefore, that Mr. Baker does not labour under the common illusion that a very great undertaking must necessarily lie the work of very great men ; and, indeed, he told the Mechanical Engineers at Edinburgh that he would be sorry not to believe that there were plenty of engineers and contractors in England, Europe, and America capable of building a Forth Bridge, if called upon to do so ; and that, in his opinion, if the engineers and contractors of the Forth Bridge deserved the praise which had been so liberally awarded them, it could only lie on the grounds that they had done their work as well, probably, as any one else would have done it. Sir John Fowler’s professional training began with level and theodolite in the north of England, and Mr. Baker’s with hammer and chisel in one of the oldest ironworks in South Wales. After the usual preliminary training of an engineering student, Mr. Baker was articled to Mr. H. H. Price, civil engineer, in whose workshops and draw- ing - office he acquired practical experience in foundry, forge, and manufacturing processes, and the designing of machinery and ironwork of all kinds. At the works referred to were made, a hundred years ago, Trevithick’s first Cornish lumping engines; and long before the eve of the jiverpool and Manchester Railway, strange loco- motives, with spur gearing and racks, and others with double bogies, some of which have been illustrated by us, were turned out of the works, together with marine engines and steamboats of the earliest type. The portfolios of working drawings thus embodied the whole history of the develop- ment of the steam engine in its application to rail- ways, navigation, mining, smelting and rolling metals, and to other purposes. After three years practical work at this branch of engineering, Mr. Baker then underwent a further period of training elsewhere in surveying, levelling, and the designing of works in masonry and brickwork. Shortly after his arrival in London, Mr. Baker en- tered Sir John Fowler’s office, and then gradually took a more and more active part in the many important engineering works then being carried out and proposed, including amongst others the Metropolitan Railway, and other railways in and around London. Mr. Baker was at that time a constant contri- butor to the columns of Engineering, and his articles on “ Long- Span Bridges,” first published by us, twenty-three years ago, were soon after republished in America, Germany, Austria, and Holland. From these early days to the pre- sent time, Mr. Baker lias been associated, in one capacity or another, with important bridges too numerous to mention in different parts of the world; the latest and biggest of which, the Channel Bridge, Mr. Baker, as stated at the Society of Arts, undertook to investigate as an interesting scientific problem, out of consideration to the high position of its promoters and designers, Messrs. Schneider and Hersent, and not as a promoter of the project him- self in any sense of the word, but confining himself entirely to the consideration of the question of the best design, and the probable cost of Messrs. Schneider and Hersent’s bold project. Whilst on the subject of bridges it may be interesting to recall Mr. Baker’s statement at the Institution of Civil Engineers, that it had fallen to his lot to repair and strengthen the three great historical bridges of their first President, Telford ; namely, the Menai Suspension Bridge, the Build was cast- iron arched bridge, and the Over masonry arch bridge across the Severn near Gloucester, and that he had succeeded in restraining the local authorities from pulling two of them down, or doing anything which would affect the appearance of these works as left by his great predecessor Telford. Although in connection with the subject of the Forth Bridge it is fit that we should refer at some little length to Mr. Baker’s connection with bridge engineering, the Proceedings of the Institution of Civil Engineers, the “ Encyclopaedia Britannica,” and many other publications, and our own columns, bear witness that he is no less interested profes- sionally in tunnelling, ship railways, or other classes of work offering the fascination of novelty and diffi- culty. Mr. Baker holds an official position under the War Department as a civil member of the Ordnance Committee, to whom all questions affecting the design of guns are referred. He lias also advised the Metropolitan Board of Works during the past twelve years, and many other public bodies, on important engineering works of a varied character projected or undertaken by them. Mr. Baker is a Member of Council of the Insti- tution of Civil Engineers ; of the Society of Arts ; of the British Association for the Advancement of Science ; and also Past-President of the Mechanical Science Section of the latter Association. He is an Honorary Member of the Society of Engineers ; of the American Society of Mechanical Engineers, and of other scientific and literary bodies ; and a Lieutenant-Colonel in the Engineer and Railway Volunteer Staff Corps. Sir Thomas Tancred. Sir Thomas Telby Tancred, the eighth baronet of Lis line, was brought up in the office of the well- known engineer, the late George Willoughby Hemans. He left England in 1865, shortly after the term of his pupilage had expired, and obtained a position in the Public Works Department of New Zealand. After a time he abandoned the profession in favour of sheep farming, in which pursuit lie distinguished himself, becoming a famous breeder, and receiving many medals at different exhibitions. In 1876 Sir Thomas Tancred returned to England, and became associated with Mr. Falkiner as con- sulting engineer for the New Zealand Government, the business being carried on under the title of Messrs. Hemans, Falkiner, and Tancred, and under that of Falkiner and Tancred, as con- tractors for public works. The partnership was dis- solved in 1886, and afterwards Sir Thomas carried out large contracts in Asia Minor, besides com- pleting the Delagoa Bay railways, a work that was very rapidly executed under his own supervision. He is at present engaged in constructing a railway across the Isthmus of Tehuantepec, over nearly the same route as that located by the late Captain James B. Eads for his proposed ship railway. Sir Thomas Tancred became an associate member of the Institution of Civil Engineers in 1868, and like Mr. Falkiner has practised as an engineer, besides having been a contractor on a large scale for public works. Mr. William Arrol. Mr. William Arrol, like many other famous con- tractors, is essentially a self-made man, who has risen from the humblest position occupied by a worker in iron, to that of one of the principal con- tractors in the United Kingdom. Mr. Arrol, who was born at Paisley, was apprenticed to a local blacksmith at the age of thirteen ; he learned his trade for four years, and it need not be said that he learned it well. By the time he became a journey- man, a financial crisis paralysed Scotland, and work being difficult to obtain, he went to England, where, for a considerable time, he followed his trade, arid acquired a varied stock of knowledge that was to serve him well at a later period. Always learning, and always saving money, to aid him in commencing the independent career of which he had already laid down the main outlines, Mr. Arrol — when times grew better — returned to Scotland, and found employment in various capa- 282 ENGINEERING. [Feu. 28, 1890 r cities, for all of which he was thoroughly fitted, hy virtue of his energy, industry, and versatile talent. Whether working as a blacksmith, a fitter, or a boilermaker, his work v/as well done, and was always characterised by the touch of originality which distinguishes the man born to command from the one made only to obey. To do everything he undertook well, to forsake the grooves prescribed by established handicraft, for new and bolder ways, and never to avoid a menial task that might accom- pany the undertaking in hand, was characteristic of Mr. Arrol. Speaking recently to some of his friends who presented him with a mark of their esteem, he said: “ Whatever I went to I put my whole mind to. Sometimes I was sent to clean the Hues instead of repairing the boilers, but I never shirked the duty.” It is in this that lies one of the chief causes of his success, “ that he never shirked his duty.” It was inevitable that Mr. Arrol should I’ise and rise quickly ; before long he changed from the man-of-all-work to the foreman of the bridge and boiler departments, in the works of Messrs. Laidlaw and Sons, of Glasgow and Edinburgh. Here he remained for some years, gaining the experience which was neces- sary for his coming advance- ment. Twenty years ago the time arrived when he con- sidered himself justified in making his first and inde- pendent venture, and he boldly launched himself as a contractor and repairing en- gineer, with the munificent capital of 85 1 . — the savings of his life. Success was certain , though Mr. Arrol did not know it, because he had the good fortune to possess the ele- ments that, when combined, command success. It is in- teresting to know that twenty years ago he purchased his first engine for 181. , his first boiler for 251., and the few tools he could afford, and which we may be sure he knew how to select to the best advantage, and how to turn to the best account. How many times during the last few years must Mr. Arrol have recalled this, his first poor but all-important ven- ture, as he walked through the enormous shops and works he laid down to carry out the Forth Bridge con- tract. For two years after he started in business for himself, Mr. Arrol’s life was that which has been led by thousands of other men under similar circumstances, a period of hope and disappointment, of waiting made tolerable only by patience and determination to succeed. In his case, how- ever, success came early, and within three years he had the years 1882 and 1887. In the mean time Sir John F owler and Mr. Baker had decided that they could safely place the most important part of the work of the Forth Bridge contract in Mr. Arrol’s hands, and it is needless to say that Mr. Arrol has j ustified the confidence which the engineers placed in him. Mr. Travers Falkiner. Mr. Travers H. Falkiner is a member of a well- known family long since settled in Ireland, of which his brother Richard Falkiner, of Mount Falcon, County Tipperary, is the head ; he has been a member of the Institution of Civil Engineers since 1803. Like Sir Thomas Tancred, he was a pupil of the late George Willoughby Hemans, and until the From a photograph by John Fergus, Lirgs, MR. WILLIAM ARROL. advanced so far in means and reputation, that he was death of that well-known engineer, was closely asso- intrusted with the contract for iron bridges on the ciated with him in professional work, as assistant, Glasgow, Hamilton, and Bothwell Railway, one of them being a very large structure spanning the Clyde. Then followed the erection of another important bridge over the Clyde adjoining the Glasgow Central Station of the Caledonian Railway, and it was for this work that Mr. Arrol devised a number of special machines for drilling and rivetting up work, which, with necessary modifications, were so largely used on the Forth Bridge. The Forth Bridge Company in 1873 entered into a contract with Messrs. W. Arrol and Co. for carrying out Sir Thomas Bouch’s design, and when the scheme was abandoned, after the failure of the Tay Bridge, the reconstruction of this work came into Mr. Arrol’s hands, and was carried out by him between representative, and finally .as partner, together with Sir Thomas Tancred, in conjunction with whom he acted as consulting engineer to the New Zealand Government. In 1876 this connection was extended by Mr. Falkiner and Sir Thomas Tancred becoming contractors on a large scale, and together they executed many important works, including railways, harbours, piers, water works, sewage works, and arterial drainage. Previous to his taking up a part of the Forth Bridge contract, lie had carried out for Sir John Fowler and Mr. Baker, the Limerick and Kerry Railway, the Tralee and F err it Railway and harbour, and the Didcot, Newbury, and South- ampton Railway, works amounting to 1,500,0001. Amongst other undertakings completed by him in Ireland, aretheDungarvon and Lismore Railway ; the Killorglin Railway and water works for Waterford, Wexford ; and the Rathmines and Rathgon town- ships, Dublin. Although in important practice as a contractor, Mr. Falkiner has never abandoned his connection as a civil engineer, and has been associated in that capacity with several works of considerable importance. Mr. Joseph Phillips. The fourth member of the firm of contractors for the Forth Bridge, Mr. Joseph Phillips, commenced his professional career in 1844, as a pupil to Messrs. Grissell, of London, and after serving his time he entered the service of Messrs. Fox, Henderson and Co., who were then building the Exhibition of 1851. When the firm erected the Crystal Palace at Syden- ham, Mr. Phillips acted as one of their outdoor super- intendents, and he afterwards was in charge of the con- struction and erection of Newark Dyke Bridge, on the Great Northern Railway, the largest ever constructed on the Warren truss principle. His next work was the Bir- mingham Railw r ay Station roof, which is of 212-ft. span, and at that time was by far the largest roof in existence. Since then Mr. Phillips has frequently been consulted by engineers on the subject of large-span roofs, and has carried many into execution. While still in the employ- ment of Messrs. Fox and Henderson he paid much attention to the system of sinking caissons by com- pressed air, invented by Mr. Hughes, and first adopted in constructing the founda- tions of the Rochester Bridge by Messrs. Fox, Henderson, and Co. Mr. Phillips joined the firm of Messrs. Cochrane and Co., of Dudley, in 1856, as their manager, and he sub- sequently undertook for them the erection of such well- known structures as West- minster Bridge, and the Charing Cross and Cannon- street railway bridges over the Thames. He was also associated with the same firm in the construction of the bridge across the Mersey at Runcorn. Further recogni- tion of his ability came with the adoption of his patent for wrought - iron caisson cofferdams, put down by open sinking or by com- pressed air, for the most difficult parts of the Thames Embankment, and, by the Government, at the Spithead forts. Later on he was associated with the late Mr. T. Parry in the contract for the Central Railway Station and line at Liverpool, and the Whitehaven Ducks. He afterwards carried out by himself the contracts for the Campos Bridge over the River Para, for the Brazilian Government ; the extension of the Derbj Water Works(under Mr. Hawkesley), and the Great Western Dock at Plymouth, for the Great Western Railway Company. The foregoing are only some of the works upon which Mr. Phillips has been engaged, but, of course, he has besides undertaken many others, for which much skill and ability were necessary Mr. Phillips’ career has been all the more re- markable because he was removed from active life for a long while by a very serious illness, at a time when he was busily engaged upon important matters, and which, after his recovery, left him in a much less advantageous position for progress than lie had formerly occupied. Since the starting ENGINEERING 283 Feb. 28, 1890.] of the Forth Bridge seven years ago he has resided on the spot. Mr. Phdlips was specially interested in the sinking of the deep foundations of the main piers, and in the execution of which the contractors co-operated with the eminent French contractor M. Coiseau. The difficulties of that part of the undertaking will he realised by what we have already said. Since the foundations were com- pleted, Mr. Phillips has been actively engaged with Mr. Arrol in superintending the erection of the superstructure. Monsieur L. Coiseau. Tt would be, of course, too much to say that the foundations for the piers of the Forth Bridge could not have been so successfully carried out by English workmen and the firm of contractors who executed the remainder of the work ; but it is certain that it was a wise decision to entrust this part of the undertaking to some one who had achieved a high reputation in the specially difficult work of sinking large foundations to a considerable depth, by means of compressed air. On the Continent works of this kind had been carried out on a much larger scale, and under greater difficulties than in this country, and no firm in the world has earned so high a reputation in this field as MM. Hersent and Couvreux. At the time — about 1880 — when these contractors were carrying out the Antwerp Harbour works, at a cost of more than a million and a half sterling, their engineer-in-chief, M. L. Coiseau, had the responsibility of the foundations, a work similar in many respects to those of the Forth Bridge. Before this M. Coiseau had been engaged on heavy contracts upon the Suez Canal and the regulation of the Danube at Vienna. For a time he was a partner of Sir Thomas Tailored, and so became familiar with English methods of carrying out work, while at the same time he grew to be favourably and widely known by English engineers. It was during this period that he con- structed a railway in Asia Minor. At the present time M. Coiseau is engaged in completing a large contract for the improvement in the port of Bilbao, on extensive railway undertakings in South America, and on other important works. There is no occasion for us to enlarge here on the manner in which he carried out the sub-contract for the sinking of the Forth Bridge caissons, as the details have been given on a previous page, but we may add that many important appliances used for pneumatic foundations have been designed by M. Coiseau.* * We propose in .an early issue to publish portraits of all the contractors for the Forth Bridge, it not having been possible to do this in the present issue. THE PHYSICAL SOCIETY. At the meeting of the Physical Society, held on February 21, Professor G. Carey-Foster, F.R.S., past- president, in the, chair, Mr. S. Evershed was elected a member of the Society. The following communications were read : “ On a Carbon Deposit in a Blalec Telephone Trans- mitter,” by Mr. F. B. Hawes. The author exhibited photographs of the interior portions of the transmitter on which the deposit had taken place. These portions con- sist of a metal diaphragm, a highly polished carbon button, and a platinum contact-piece carried by a German silver spring placed between them. The diaphragm pre- sented a mottled appearance due to the deposit, but the part which had been behind the German silver spring seemed comparatively clean. The deposits on the carbon button and German silver spring were much less dense than that on the exposed parts of the diaphragm, and the space near the point of contact between the platinum and carbon was free from deposit. The deposit was fairly adherent, considerable rubbing being necessary to remove it, and on examination under the microscope particles of copper and metallic crystals could be seen. The author believes the deposit due to some kind of bombardment of carbon particles, but was unable to say why it should occur, or why the varnished diaphragm should receive the greater deposit, although it was further from the carbon than the German silver spring. Mr. C. V. Boys said the photographs reminded him of a phenomenon he observed some time ago on a glass sheet against which one terminal of a dry pile had been resting for some weeks. Just as on the carbon button the glass near the point of contact was clean and had a comet- shaped deposit formed around it. He could offer no explanation of the appearance. “ The Geometrical Construction of Direct Reading Scales fjr Reflecting Galvanometers,” by Mr. A. P. Trotter. In a recent paper “On Galvanometers,” by Professor W. E. Ayrton, F.R.S., T. Mather, and Dr. W. E. Sumpner, read before the Society, the opinion was expressed that proportionality of scale reading to current was very desir- able, and the present paper shows how to bend a scale of equal divisions so as to give the required proportionality. Suppose the currents required to produce several deflec- t ons have been experimentally determined. A full-size plan of the scale is then drawn, and radial lines from the points on the scale at which the observations were taken are drawn towards the centre of the mirror. Let these radii be numbered 0, 1, 2, 3, &e., commencing from zero azimuth. According to the procedure recommended, distances proportional to the several current strengths are marked off along the edge of a strip of paper, a few inches being left over at each end. Call the marks a, h, c, d, &c., a being the zero point. Two points on the radii 0, 1, and equidistant from the mirror, are now found such that the distance between them is equal to that between a and b on the strip, and the points marked by fine needles stuck in the board. The zero end of the strip is now fixed so that the marks a, and b lie against the needles, and the strip is swept round until the mark c coincides with the radius 2, where also a needle is placed. Repeating the process gives a series of points, which 011 being joined form part of a polygon. A line can then be drawn between the inscribed and cir- cumscribing curve, which has the same length as the sum of the straight lines, and this is the curve to which the original scale may be bent, so as to give proportional readings. Diagrams showing such curves constructed from the calibrations of instruments given in the paper above referred to, accompany the paper. The author showed that a family of curves may be drawn, each of which satisfies the required condition. Of the two limiting curves one is tangential to the usual scale line at zero azimuth and the other passes through the vertical axis of the mirror. The flattest of the various curves is generally the most convenient. Mr. J. Swinburne asked whether good definition could be obtained when such curved scales not equidistant from the mirror were used, and also whether it was not easier to divide a flat scale unequally, so that the readings are pro- portional to the current 'l Mr. Trotter, in reply, said Dr. Sumpner thought there would be no difficulty as regards definition with the flat curves shown. He (Mr. Trotter) also added that a curved scale might be advantageous in reading the deflec- tions from one side of a table, as the more distant part of the scale could be more nearly perpendicular to the line of sight. For such an arrangement, however, a parallel beam of light would be required. “A Parallel Motion Suitable for Recording Instruments, ” by Mr. A. P. Trotter. This is a modification of Watt’s parallel motion in which the two fixed centres are on the same side of the line described by the “ parallel point.” The arrangement consists of two vibrating arms one of which is twice the length of the other, and whose outer ends are jointed respectively to the middle and end of a short lever ; the free end of the latter describes an approxi- mate straight line. The motion was arrived at by con- sidering the curve traced out by a point on the radius of a circle such that its distance from the circumference measured towards the centre is equal to the radial inter- cept between the circle and a tangent line. The equa- tion to thecurve is r — 2 — sec. 6 (conchoid of Nicomedes), and the radius of the osculating circle at the point where the intercept is zero is given as half that of the initial circle. This osculating - circle, the author finds, practi- cal 1 y coincides with the curve over a considerable angle (10 deg.), and hence may replace this part of the curve ; hence the motion. The author thinks that the motion will be useful for recording barometers, ammeters, and voltmeters, as it is more compact than that of Watt, and needs no fixed point beyond the straight path. Owing to the absence of Professor S. P. Thompson, his paper “ On Bertrand’s Refractometer” was not read. LAUNCHES AND TRIAL TRIPS. The trial trip of the s.s. President Carnot took place on Wednesday, February 5, over the measured mile at Long Reach in the Thames. This vessel has been constructed by Messrs. Edwards and Symes, of Mill wall, London, and her dimensions are : Length, 175 ft. ; beam, 271 ft. ; depth, Oft. She has been fitted by the builders with compound surface-condensing screw engines of 300 indi- cated horse-power, having cylinders 18 in. and 30 in. in diameter with a stroke of 22 in. One steel boiler with two furnaces constructed for a working pressure of 1101b. per square inch, supplies steam to the engines. With 700 tons on board the draught of water is only 8 ft., and her speed on the trial was 81* knots per hour. A steel screw steamer named the Latona, and built by Messrs. Russell and Co., Port-Glasgow, was taken on her trial trip on the 8th inst. Her dimensions are : Length, 323 ft. ; beam, 42 ft. ; depth, 23 ft. 0 in. ; and she had a full cargo on board. Two runs were made on the measured mile on the Clyde, the speed obtained being 10j knots, and the machinery worked very smoothly at 72 revolutions. The engines, which are by Messrs. Dunsmuir and Jackson, of Govan, have cylinders 24 in., 89 in., and 04 in. in diameter, with a stroke of 45 in., and have been built under the superintendence of Messrs. Flannery and Blakiston, of Liverpool and London. The boilers are extra large double-ended, and gave ample steam on the trial. The vessel is owned by Mr. G. hi. Steenes, of Liverpool. The London and Glasgow Shipbuilding and Engineer- ing Company, Limited, launched on Wednesday, 12th inst., from their yard at Govan, a steel twin-screw steamer, named Nanchang, built by them to the order of Messrs. John Surre and Sorts, London, for the China Steam Navigation Company. The steamer is of the fol- lowing dimensions : Length, 255 ft. ; breadth, 36 ft. ; depth of hold, 22 ft. 6 in. ; and her gross tonnage will be about 1750 tons. Twin engines of the triple-expansion type have been constructed by the company at their works in Glasgow. The cylinders in each engine are of the fol- lowing diameters, 14 in., 23 in., and 37 in., with a stroke of 30 in. Steam is generated in two single-ended boilers made of steel, and measuring 12ft. 9 in. by Oft. 9 in., having in all six furnaces. The engines, it is expected, will develop 1600 horse-power. The s.s. Kilmore, which has been built by the Edwards Shipbuilding Company, Howden-on-Tyne, went on her official trial on the 15th inst. ; she is of the following dimensions: Length, 287 ft.; beam, 38ft.; with 18ft. depth of hold, having a. deadweight capacity of 2700 tons. The Kilmore has been fitted with triple expansion machinery by Messrs. David Hollo and Sons, of the Fulton Engine Works, Liverpool. The engines have cylinders 22 in., 34 in., and 55 in. in diameter, with 42 in. stroke. Steam at 160 lb. pressure is supplied by two large single- end steel boilers. The machinery gave every satisfaction during the trial. The steamer Pei'sis, built by Messrs. Mackie and Thom- son, Govan, to the order of Messrs. Aiken and Walker, Glasgow, went on her speed trials on the Firth of Clyde on Saturday, the 15th inst., and attained a speed of 11 J knots on the measured mile, the engines working smoothly. The vessel is of the following dimensions : Length, 260 ft. ; breadth, 37 b ft. ; depth, 24 ft. 9 in.; and the carrying capacity is 3000 tons deadweight, the gross tonnage being 1900 tons. The engines were constructed by Messrs. Muir and Houston. They are of the triple-expansion type, having cylinders 18 in., 29J in., and 47 in., with a stroke of 39 in. Steam is generated in two boilers 12 ft. 3 in. by 9 ft. 6 in., working to a pressure of 160 lb. to the square inch. On trial the indicated horse-power was 1000. On Monday, the 17th inst., Messrs. Caird and Co. launched from their yard at Greenock a steel screw steamer named Netherby Hall, constructed for Messrs. R. Alexander and Son, Liverpool. The vessel in ques- tion is of the following dimensions : Length, 350 ft. ; breadth, 42 ft. ; and depth 29 ft. 9 in. ; and of 3250 tons gros*. The builders will supply engines of the triple- expansion type to indicate 2000 horse-power. The steamer Weimar, built and engined by Messrs. Ramage and Ferguson, Leith, for Messrs. James Currie and Co.’s passenger service between Leith and Hamburg, went on her speed trials in the Firth of Forth on Monday, the 17th inst., experiencing unfavourable weather; but, notwithstanding, a speed of 131 knots was easily obtained. The Weimar is about 1550 tons gross, being 254 ft.. long between K. and F. ; breadth, 34 ft. ; and depth moulded, 25 ft. The engines are of the triple-compound type, and on trial indicated 1350 horse-power. The cylinders are 23 in., 37 in., and 60 in. in diameter, with a stroke of 42 in., and steam is supplied from two large single-ended steel boilers. O 11 Tuesday, the 18th inst., Messrs. Raylton, Dixon, and Co. launched from their Cleveland Dockyard a large steel screw steamer, which has been built to the or,der of Messrs. W. Ross and Co., London. The particulars of the vessel are: Length, 351ft.; breadth, 42ft. 6 in.; depth moulded, 29 ft. 6 in.; witli a deadweight capacity of about 4550 tons. Her engines will be fitted by Messrs. T. Richardson and Sons, Hartlepool, on their triple-ex- pansion principle, with cylinders 21 in., 44 in., and 72 in. in diameter, by 48 in. stroke. On leaving the ways the vessel was christened Storm King. On February 19 there was launched from Messrs. Craig, Taylor, and Co.’s Thornaby Shipbuilding Yard, Stockton- on-Tees, an iron screw steamer named the Shaftesbury, and of tlie following dimensions : Length, 278 ft. ; breadth, 37 ft. ; depth, 19 ft. 8 in. The engines, of the triple- expansion type, are being constructed by Messrs. West- garth, English, and Co., Middlesbrough-on-Tees, and have cylinders 20 in., 33 in., and 54 in. in diameter by 36 in. stroke. Two large steel boilers supply steam at 150 lb. pressure. The vessel has been built to the order of Mr. William R. Rea, of Belfast. Messrs. Gourlay Brothers, Dundee, launched on Wed- nesday, the 19th inst., a steel screw steamer named Circassia, built by them to the order of Messrs. N. Pacquet and Co., Marseilles. The vessel is 315 ft. long, 37 J ft. broad, and 25 ft. deep, the registered tonnage being 2240 tons, and the net 1448 tons. Triple-expansion engines, constructed by the builders, are being fitted on board, the cylinders being 25 in., 40 in., and 64 in. in diameter respectively, with a stroke of 45 in. A four-masted barque of 2050 tons named Mayhill was launched on the 20th inst. from the yard of Messrs. Alex. Stephen and Sons, at Dundee. She is 292 ft. long, 41 ft. broad, and 23 ft. 9 in. deep. The Electric Light at Philadelphia. — The city council of Philadelphia has under consideration a pro- position to establish an electric light plant of 12,000 lamps at a cost of 60,0001. The cost of maintenance is esti- mated at 18,0001. per annum. 284 ENGINEERING. [Feb. 28, 1890. INDUSTRIAL NOTES. In the February report of the Boilermakers and Iron Shipbuilders the opening paragraphs on the monthly returns give just a hint of the possible limit having been reached in the orders for the construction of new vessels. They say: “Shipbuilding and the various industries that depend upon it are active and appa- rently as brisk as ever. One hears everywhere predic- tions that the present year will see the end of this wonderful production of steam shipping. Still, supply in shipping seems to beget demand, and fresh avenues for maritime commerce are continually opening by which employment is found for increased tonnage, and the area of consumption for British coal is extended.” This paragraph is cautiously worded, and seems in- tended to give the hint to members that prudence and moderation are required. The next paragraph explains that “ the great increase in the prices of steel, iron, and coals, has no doubt checked the demand for vessels for the time, except those wanted for special pur- poses.” It then proceeds to comfort the members with the gratifying news that in so far as the present year is concerned they are safe. At the beginning of the year 521 vessels of 872,957 tons were in course of con- struction, which is more than last year started with by 61,000 tons, or an increase of 8 per cent. It there- fore concludes that the output of 1890 will exceed that of last year. Nearly one-third of the total is for foreign and colonial owners. Further encouragement for the present year is to be found in the fact that 2,000,000/. are to be expended in building vessels for the navigation of the Danube, in connection with a gigantic scheme just brought to a successful issue in London. These vessels are for a special purpose, and will not mean increased tonnage for the ordinary freight market, to the danger of over- production. The returns as to members on the funds show a substantial decrease under each head, except as to sick benefit, in which class there is an increase of 466. There were fewer out of work, on strike, and on superannuation, the total decrease in these three classes being 112. The proposition for a “ ten-shilling levy ” lias been carried by a majority of 3122, the votes being : For, 12,860; against, 9788. The lodge secretaries report that many of the members who voted against have now changed their minds, and express themselves in favour of this fighting defence fund. Some have suggested a pro rata levy on the advanced rates secured during the last two years, but this mode of taxation upon increment received is not generally favoured. Attention is drawn to the fact that the branches which have received most help from the Society have voted against the levy, and the report says that the members spend more in one week in the public-house than the entire levy, and think nothing of it. The full levy is to be paid by all the members except apprentices ; the 10s. may be paid down at once, or it must be paid in four instalments of 2s. 6d. eacli per quarter. If the amount is not paid it will be booked as arrears of contribution. The engineering trades throughout the Lancashire dis- tricts show no sign of lessened activity in any branches. It is true that there has been a falling off in the weight of orders for new work for shipbuilding purposes, but all branches are so fully employed that the effects are not felt, and will not be felt for some time. The general activity which has existed for a long period is well maintained, and might almost be said to have in- creased in connection with boilermaking, stationary engine building, machine tools, and other branches, all of which are very full of work — sufficient to keep all skilled men fully employed for a long time to come. The great development and expansion of electrical engineering have had the effect of increasing the demand for skilled men in several branches of work, especially in connection with stationary engines. The proposed expenditure of 2,000,000/. in connection with the navigation of the Danube seems already to have given a spurt in some branches, for the engine shops in various parts of the country are so full of orders that new orders for machinery have been refused, as the firms could not guarantee deliveries at the dates wanted. The forge works are kept going day and night, some heavy forgings being on hand. Influenza has broken out in Oldham to such an extent that some 500 workmen at Messrs. Platt’s engineering establish- ments, employing nearly 10,000 persons, have been more or less indisposed. The pressure of work at these establishments is so great that the absence of any considerable number of men will be felt immediately. In the Sheffield and Rotherham district there is no falling off in industrial activity, but quite the reverse. The armour plate mills are full of work, with a pro- spect of continuance for many months to come. One of the largest contracts ever obtained in Sheffield in this branch has been secured by Messrs. John Brown and Co. and Messrs. Cammell and Co. from the Admiralty. In the Bessemer steel department of trade the various firms have work on hand to keep them fully employed for months to come. The stove- grate industry is actively brisk, and the employers have conceded the demand for 54 hours per week, from 57 hours previously worked ; but the masters refuse at present to grant the advance in wages asked for of 10 per cent. As both parties seem unwilling to give way, a strike may possibly result. In the present state of trade, however, it is hardly likely that any serious cessation of labour will take place. Some of the men employed in the spoon and fork department of Messrs. Huttons removed their tools on the expiry of the notices, but in other cases the notice was withdrawn. The further action of the men will be decided at a general meeting. The sheet rollers of the district are organising themselves with the view of securing an advance in wages and other advantages corresponding to those conceded to other workmen. In the crucible steel trade there is a plethora of work and orders ; the steel rail industry is flourishing, and there is a strengthening of prices. The threatened strike in the coal trade is causing much anxiety in many quarters in this district. Throughout the Cleveland district trade continues active in all branches. Even the speculators are more cheerful in the prospect of better prices. The unrest of the miners, and the prospect of a strike, seem to have assisted in bringing about a feeling of satisfac- tion, because of the greater readiness of consumers to buy, in view of the possible rise in prices. Already the market is said to be “stronger” in consequence. There is a small dispute at the Teesside Iron and Engi- neering Works, where about thirty of the labourers connected with the boiler shops and bridge yards, demanded an advance of 2s. per week in wages. This the employers refused, and the men were paid oft'. A similar demand was recently made by a portion of the labourers at the Cleveland shipbuilding yard and was refused. The miners of Cleveland and North York- shire, and the Blast Furnacemen’s Association, have determined to federate for mutual assistance and pro- tection, in case of labour disputes. The votes of the members are to be taken by March 4, as to the terms of arrangement, amount of contributions, and other matters of constitution, organisation, and government, for carrying out the proposed union. In all other respects labour movements are quiet at present, the men being fully employed, overtime being very general, and wages in most branches fairly good. The labourers’ federation, of which much was heard a short time ago, does not seem to have produced much effect, for in the two instances in which the labourers demanded a rise in wages, the employers have refused, without, it would appear, suffering much inconvenience. A very curious tale is told with respect to a recent dispute in connection with one branch of the iron trades. A demand was made for increased pay for overtime by the day workers ; the firm refused, unless the men worked the full 54 hours per week, after which increased rates would be paid. But many of the more skilled men worked by the piece, and they did not, as a rule, work more than four days per week, their plea being that the nature of the work was so exhausting that they were not able to stand more. When the matter was investigated it was found that these men crammed into the four days at full speed a whole week’s usual work, at high rates of pay ; but they kept their helpers unemployed during the first two days, and only paid them for four, so that while the higher paid got a full week at high rates for four days’ work, the less paid and more laborious workers lost two days’ work and wages in each week. Truly man’s inhumanity to man makes countless myriads mourn. The Society intervened to minimise this inconvenience to the masters and injustice to fellow workmen. The movement of the brassworkers in Birmingham for an advance in wages of 15 per cent, has been so far successful that many of the large firms conceded the terms asked for without a strike. In some cases the men turned out, ami one by one the employers gave way. The number involved in the dispute was about 7000, but only a comparative few went on sti'ike. The work of the town was not seriously inconvenienced thereby. A very interesting ceremony was performed at Old- ham on Saturday last by Mr. George Howell, M.P., who formally opened the new offices of the Card and Blowing Room Operatives’ Association, in Union- street. The premises are said to be the third in architectural importance in the town ; the Public Library stands first, the Lyceum second, and these new premises third in order. A large company assembled, including Mr. John Burnett, the labour correspondent to the Board of Trade, the chairman and secretary of the Employers’ Association, and a large number of representatives of the textile trades in Lancashire and adjoining counties. The opening ceremony was fol- lowed by an excellent dinner at which speeches were made, by a “ Lancashire tea” in two or three large halls, and two large public meetings and concerts in the two large co-operative halls in the town. It was stated at the dinner that this was the first time in which the employers were the invited and welcomed guests of the operatives, at a public dinner. And, singularly enough, this was the class of operatives whose members were on strike for thirteen weeks, only last year ; the dispute was finally settled in about half an hour by the chairman of the Masters’ Association, and Mr. Robert Ascroft, a well-known townsman, a friend of the workpeople, and solicitor to the Association, at a friendly interview. The agitation among the railway employes of the North-Eastern Company seems to be entering on the acute stage. With one voice they recently determined to continue their agitation, and on the main points they were “solid and undivided,” whilst as regards the mode of conducting it, they practically agreed to leave the matter in the hands of the executive of the union. The temper of the men at present seems to be that of no surrender, but to offer arbitration as the alternative to a strike. There are about 5000 members of the Amalgamated Society on the North-Eastern, besides many who follow their lead. The employes on the Irish Great Northern Railway have determined to strike on March 4 if their demands for an advance of 2s. per week with pay for Sunday work and overtime, after sixty hours, have not been acceded to. One curious fact is observable in connection with labour and capital at the present time, namely, that the leaders of labour movements and the more intelli- gent of their followers are following very closely the reports of the great companies and others whose accounts are published, finances disclosed, and divi- dends declared. The publicity and criticism of these yearly or half-yearly reports will in the end be advan- tageous, because the workpeople will be better able to understand whether or not the state of trade will warrant a rise in wages, or justify an attempt to reduce the working hours. More light will prevent mistakes. The eight hours’ movement has had its innings to some extent during the last fortnight. Deputations have waited upon the Home Secretary, Mr. Gladstone, Lord Dunraven, and Lord Randolph Churchill to press their views. Members of Parliament and candidates for Parliament have also been, and are being, interviewed on this question. A special round robin has been signed by a large number of members, asking the Government to grant a day for a debate on the Eight Hours’ Bill. The promoters are careful to explain that it is only intended for miners, forgetful of the fact that this is class legislation with a vengeance. The condition of things in the coal trade is not very reassuring. Nearly 400,000 notices, it is said, have been given by the miners in various parts of the country for an advance in wages, in most cases of 10 per cent. , but in Durham and Northumberland of 15 per cent., by some 40,000 men. In some districts there is an eagerness for the fray, but in some others the men are more carefully weighing the probable cost. For the moment the more ardent and advanced men are to the forefront ; moderate men, and moderate views, are at a discount. Thoughtful and prudent men are anxious as to the result of all this feverish excitement in connection with labour. The first batch of notices was given by the miners of South Staffordshire on Saturday last, to terminate all engagements in fourteen days unless the 10 per cent, is granted. Some 4000 men and boys are involved in this district. In the Leicestershire district, it is said, the men will be rather glad of a holiday to plant their gardens. But what of those who have no gardens to plant ? In Cumberland a further 10 per cent, has been con- ceded, making a total of 40 per cent, advance since the agitation commenced. The strike will not therefore extend to this district. Some advance has also been conceded in some parts of Scotland, so that it is doubtful whether the strike will extend generally across the border. In the Lancashire district the final decision has not yet been given, but the men hope that a strike may be averted. In Lanarkshire the advance conceded amounts to 6d. per day, and the men are now considering whether they shall not adopt a four days per week policy, so as to force all mineowners to give the full advance named. In Fifeshire the men are demanding a further advance so as to make up the full 20 per cent, which they demanded some time ago, but which was settled by a compromise. At their last council meeting it was agreed to give in their notices, terminating all con- tracts, to expire at the same time as the other miners’ notices. A New Brunswick Bridge. —An iron plate girder bridge above Gordon Falls, Pollet River, New Brunswick has just been completed. The span is 104 ft. Feb. 28, 1890.] ENGINEERING. AGENTS FOR “ENGINEERING.” Austria, Vienna : Lehmann and Wentzel, Karntnerstrasse. Calcutta : G. C. Hay and Co. Edinburgh : John Menzies and Co., 12, Hanover-street. Franck, Paris : Veuve J. Boyveau, Librairie Etrangire, 22, Rue de la Banque ; M. Em. Terquem. 31Ms Boulevard Hausmann. Also, for Advertisements, Agence Havas, 8, Place de La Bourse. (See below). Germany, Berlin : Messrs. A. Asher and Co., 6, Unter den Linden. Leipzig : F. A. Broekaus. Mulhouse : H. Stuckelberger. Glasgow : William Love. Italy: U. Hoepli, Milan, and any post office. Liverpool : Mrs. Taylor, Landing Stage. Manchester : John Heywood, 143, Deansgate. Queensland (North), Townsville : T. Willmett and Co. Rotterdam : H. A. Kramers and Son. United States : Sole Agent, W. H. Wiley, 16, Astor-plaoe, New York. Victoria, Melbourne : Melville, Mullen, and Slade, 262/264, Collins- street. NOTICE TO AMERICAN SUBSCRIBERS. We beg to announce that American Subscriptions to Engineering may now be addressed either direct to the publisher, Mr. Charles Gilbert, at the Offices of this Journal, Nos. 35 and 36, Bedford- street, Strand, London, W.C., or to our Sole Agent for the United States, Mr. W. II. Wiley, 15, Astor-place, New York The prices of Subscription (payable in advance) for one year are : For thin (foreign) paper edition, 11. 16s. (Id. ; for thick (ordinary) paper edition, 21. Os. 6d., or if remitted to Mr. Wiley, 9 dollars for thin and 10 dollars for thick. ADVERTISEMENTS. The charge for advertisements is three shillings for the first four lines or under, and eightpence for each additional line. The line averages seven words. Payment must accompany all orders for single advertisements, otherwise their insertion cannot be guaranteed. Terms for displayed advertisements on the wrapper and on the inside pages may be obtained on application. Serial advertisements will be inserted with all practical regularity, but absolute regularity cannot be guaranteed. Advertisements intended for insertion in the cur- rent week's issue must be delivered not later than G p.m. on Thursday. In consequence of the necessity for going to press early with a portion of the edition, alterations for standing Advertisements should he received not later than 4 p.m. on Wednesday after- noon in each week. The sole Agents for Advertisements from the Con- tinent of Europe and the French Colonies are the AGENCE HAVAS, 8, Place de La Bourse, Paris. SUBSCRIPTIONS, HOME AND FOREIGN. ENGINEERING can be supplied, post free, direct from the publisher, at the following rates, for Twelve Months, payable in advance. For the United Kingdom £19 2 ,, India, China, Japan, Borneo, Ceylon, Java, Manila, Burmah, and Straits Settlements : Thin paper copies £2 0 6 Thick „ £2 7 3 ,, the Continents of Europe and America, Australia, New Zealand, and most other countries : Thin paper copies £1 16 0 Thick „ £2 0 6 All accounts are payable to the publisher, Mr. Charles Gilbert. Cheques should he crossed “ Union Bank, Charing Cross Branch.” Post Office Orders payable at Bedford-street, Strand, W.C. Foreign Subscriptions, when sent by Post Office Order, should be advised to the Publisher. Foreign and Colonial Subscribers receiving Incomplete Copies through News-Agents are re- quested to communicate the fact to the Publisher, together with the Agent's Name and Address. Office for Publication and Advertisements, Nos. 35 and 36, Bedford-street, Strand, London, W.C. Telegraphic Address— ENGINEERING, L0UD0H. Telephone Number— 3663. ENCHNEEBING is registered for transmission abroad. Reading Cases. — Reading cases for containing twenty-six num- bers of Engineering may be had of the publisher or of any news agent. Price 6s. each. In consequence of the whole edition of the present number of “ENGINEERING” having been sub- scribed for prior to publication, the Publisher begs to say that a reprint of the descriptive matter and illustrations of the Bridge will be published early next week, printed throughout on special Plate Paper, and bound in Cloth, Gilt Lettered. Price 5s. CONTENTS. PAGE PAGE The Forth Bridge (Him.) .. 213 II Bridging the Hudson River 287 The Engineers and Contrac- 1 Notes from the South-West 287 tors of the Forth Bridge. . 276 |: Notes from South Yorkshire 287 The Physical Society 283 it Notes from Cleveland and Launches and Trial Trips .. 283,; the Northern Counties .. 288 Industrial Notes 284 l| Notes from the North 288 Railway Competition 285 | Miscellanea 288 Narrative of the Manoeuvres 280 I With 17 Two-Pane Platen illustrating THE FORTH BRIDGE. NOTICES OF MEETINGS. The Institution of Civil Engineers. — Ordinary meeting, Tues- day, March 4th, at 8 p.m. Papers to be read with a view to dis- cussion : “The Hawkesbury Bridge, New South Wales,” by C. O. Burge, M. Inst. C.E. “The Construction of the Dufferin Bridge over the Ganges at Benares,” by F. T. G. Walton, C.I.E., M. Inst. C.E. “The New Blackfriars Bridge on the London, Chatham, and Dover Railway,” by G. E. W. Cruttwell, M. Inst. C.E. Institute of Marine Engineers. — Tuesday, March 4th, at 7.30 for 8 p.m., in the Langthorne Rooms, 15 and 17, Broadway, Stratford, Essex. Paper on “ Friction of Screw Propelling- Engines,” by Mr. W. J. N. Brett (Associate). Physical Society. — March 7th. “On Bertrand's Refracto- meter,” by Professor S. P. Thompson. ENGINEERING. FRIDAY, FEBRUARY 28, 1890. RAILWAY COMPETITION. The railway passenger, in liis moments of irrita- tion, is fond of referring to the company with whom he is finding fault as a monopoly. If lie be on a branch line, or in a south London suburban train, there is probably a good deal of truth in the charge, but on the great trunk lines of the country it is quite unfounded. There are very few im- portant towns which are not served by two lines of railway, and many have three or more. Between these lines there is always very considerable com- petition for passenger traffic, even when it is more or less veiled under agreements as to fares and trains. In this country the competition seldom takes the form of a war of rates, as it does in America ; it shows itself in better accommodation, higher speed, and general convenience. These concessions to the public spread, in course of time, from the main lines to the branches, and tints the effects of competition are felt in districts where it does not exist. Numerous examples of boons given gratuitously to the travelling public must occur to every one who lets his memory wander back a few years. The Midland Company have been the greatest benefactors in this way. In 1872 they made a bold hid for passenger traffic, in which they were defi- cient, by running third-class carriages in all trains, both fast and slow. No change was ever appre- ciated by the public as much as this, since it practically reduced the cost of travelling, to all who must study economy, by 30 to 40 per cent. Three years later they altered all first-class fares to the second-class tariff, thus conferring an obliga- tion on those whom social considerations, rather than choice, obliged to patronise the more expen- sive part of the train. Of course, all the other northern lines had to follow their example in these points, and thus passengers far beyond the Mid- land system reaped the benefit. It is difficult to decide what the ultimate effect was on the finances of railway companies, although we know that the immediate action was to render the Midland Com- pany very popular with a considerable section of the public. Mr. George Findlay, General Manager of the London and North-Western Railway Com- pany, stated before the Society of Arts'*' that the etfect of the adoption of the practice of conveying third-class passengers by all trains, coupled witli the reduction of fares, was to increase the third-class traffic, and reduce that of the first and second classes. On the London and North-Western Railway in 1871 tlie gross earnings from first-class passenger traffic were 728,779k, or 13.59d. per passenger train-mile ; hut in 1888 the earnings for that class were only 480,780k, or 5.81d. per train-mile. From second- class traffic in 1871 there was earned 867,099k, or 16.17d. per train-mile ; but in 1888 only 328,771k, or 3.91d. per train-mile. On the other hand, while in 1871 the receipts from the third-class were only 999,051k, or 18.4Gd. per train-mile, in 1888 they had grown to 2,433,485k, or 29.38d. per train-mile. The total passenger receipts from all three classes combined fell from 48.22d. in 1871 to 39.16cl. in 1888. The mileage was upwards of 20,000,000 train-miles per annum. Apart from these two striking examples of concessions to railway travellers there have been many others quite, if not more, valuable, which have proceeded so slowly as not to attract much attention. The chief of these is the constant increase in speed which is taking place. In 1872 the fastest train between London and Liverpool, a distance of 201|- miles, performed the journey in 5 1 to 6 hours, while now it is accomplished in 41 hours. Between London and Manchester, 188f miles, the shortest time occupied was 5 hours, * “On Modern Improvements of Facilities in Railway Travelling.” Paper read before the Society of Arts, February 12, 1890, and published in the Journal of the Society for February 14. 285 while now it is 4|- hours. Between London and Birmingham, 113 miles, one train ran in 3j- hours, but the others were much longer on the road, while to-day all the fast trains perform the journey in 2| hours. In the entire country there are now 670 trains daily, with a mileage of 62,904 miles, having an inclusive speed of upwards of 41 miles an hour, whereas in 1871, on the ten leading railways of England, there were no more than 57 trains running at a speed exceeding 39 miles an hour. The greater part of this improvement is due to competition. The quality best appreciated by the railway traveller, next to speed, is comfort of accommoda- tion. This is increasing very rapidly, and there is no doubt that it is directly at the expense of the shareholders. A reduction of fares is sure to bring more traffic, and so is increase of speed, but no one is tempted to make a journey because the carriages are comfortable. The new carriages cost far more, both for first expense and haulage, than the old ones. In 1872, according to Mr. Findlay, the standard third-class carriage on his line was 30| ft. long and weighed about 10 tons, carrying 50 pas- sengers ; now it is 42 ft. long and weighs upwards of 18 tons, with seats for 70 passengers only. The addition of lavatories to a 42-ft. first-class carriage reduces the seating capacity from 40 to 28, or by about one-third. The companies which compete for the Scotch traffic are now about to provide lavatory accommodation for second and third-class passengers. An East Coast carriage of this kind will weigli 19 j tons, cost 860k, and only accom- modate 33 passengers of ail classes. A sleeping saloon weighs 22i tons, costs 1300k, and contains 16 berths. The Forth Bridge, however, supplies the most striking example of railway competition that this country lias ever seen. The four companies which work the east coast route to the Highlands of Scot- land have practically united to spend three millions of money in order to redress a trifling advantage on the side of the two which run to the same goal by the west coast route. Surely no system of competition could lead to greater expenditure than this. Every one will remember the premonitory outbreak of tliis competitive zeal, which showed itself in 1888 in the celebrated race to Edinburgh. Up to that time there had been a tacit understanding between the east and west coast companies that each should enjoy their natural advantages unmolested. By tlie east coast the passenger leaving London by the morning train reached Edinburgh in nine hours, and Glasgow in ten hours twenty minutes ; by tlie west coast tlie journey took ten hours to both towns. Naturally, those bound to Edinburgh were inclined to travel by tlie Great Northern line, and those for Glasgow by the London and North- Western. These, however, were only first and second-class passengers ; third - class passengers were not carried by tlie quickest east coast trains, although on tlie west coast no distinction of this kind was made. Therefore, as regards this class of traffic, both companies offered equal advantages to Edinburgh, while as regards Glasgow, tlie west was nearly two hours tlie speedier. In November, 1887, however, the Great Northern Company adver- tised that they would carry all classes of passengers in their 10 a.m. express from King’s Cross, thus practically offering to set down the third-class passenger in Edinburgh one hour before tlie North- Western Company would do so, and to convey him to Glasgow in only twenty minutes’ longer time than he could arrive there by the west coast. Tlie abstraction of traffic caused by the alteration was, no doubt, sufficiently serious in the winter months, hut when tlie tourist season set in it was not to he borne. Towards the close of May, 1888, tlie London and North-Western Rail- way Company announced that their ten o’clock expresses would complete the journey between London and Glasgow and Edinburgh in nine hours, both ways. The east coast lines re- turned the challenge by speeding tlie trains to reach Edinburgh in eight and a half hours, and Glasgow in nine hours fifty minutes. This was on July 1. The Midland Company also joined the strife by reducing their time to Edinburgh by twenty-five minutes, and to Glasgow by one hour. Matters stayed thus during the whole of July, but on the 27 tli the west coast companies announced that they too would run to Edinburgh in eight and a half hours, and immediately the east coast lines followed with a notice that their time would be eight hours. O 11 August 6 the North-Western 286 replied by adopting the same time, and up till the 12th both companies ran alike. But on the 13th the east coast train was timed to reach Edinburgh at 5.45, or in seven and three-quarter hours from King’s Cross. The west coast train accepted the challenge, and actually covered the distance in seven hours thirty-eight minutes, while the next day the east coast train did it in seven hours thirty- two minutes. A conference was then held, and it was decided that for the remainder of the month the Great Northern time should be seven and three-quarter hours, and the North-Western time eight hours. At the end of August the tension was relaxed, and both trains were timed to make the journey in eight and a half hours. This wonderful outbreak of competition took the major part of the public by surprise, since there seemed to be no greater cause for it than there had been for years past. The Edinburgh traffic had not undergone any larger extension than that of other important towns, and there was no prospect that it would. The real significance of the Forth Bridge in relation to the contest was not clearly perceived, for it was situated beyond the point where the contest ended. Yet it was the true cause of the rivalry, and its influence could be discerned in the alterations which the west coast trains to Perth underwent during the struggle north of Edinburgh. English passengers by the North- Western line had always been better situated than those who travelled via York. There are two rea- sons for this : first the distance to be traversed is less, and, second, the lines are owned by friendly companies. The carriages from Carlisle for Perth, Dundee, Aberdeen, and Inverness, instead of being taken to Edinburgh, travel via Carstairs, Coat- bridge, and Larbert to Stirling and Perth, the whole route being on the Caledonian system. Car- riages from York must pass through Edinburgh, with its long stoppage, and then over the lines of a company whose fortunes are bound up with the success of the west coast route. It is easy to under- stand that the North-Western passengers would be treated with a more benevolent form of neutrality than those who travelled by the Great Northern, and that the latter company, with their partners, should find their position so unsatisfactory that they thought it wortli while to spend a large sum of money to emancipate themselves from it. A glance at the map on page 214 will show how this is to be accomplished by the Forth Bridge. Instead of the long detour by Larbert, Stirling, and Crieff, tire route to Perth runs as nearly straight as the configuration of the country will allow, while a new and direct route is also opened to Dundee across the Tay, and thence to Aberdeen. As soon as the race to Edinburgh began, the North - Western Company accelerated their ex- presses to Perth, so as to accentuate their supe- riority on that route. They first put on a new express to Perth, leaving Euston at 10.30 and arriving at Perth at 9.35, or twenty minutes quicker than before. On July 1 this train was accelerated by forty minutes, so as to arrive at 8.45 r.M. This arrangement is still maintained, and the west coast passenger for Perth by the day train can thus start half an hour later than if he travelled by the east coast, arriving at the same time ; by the night train he starts twenty minutes later. This arrangement is not one that is likely to be con- tinued, for the Great Northern Company is adver- tising that “the time occupied on the journey between London and other stations on the east coast railways and stations north of the Forth will be shortened ” after the Forth Bridge and the railways in connection with it are opened. We can, however, make very a fair estimate how much the length of the journey will be reduced. At present the distance from Edinburgh to Perth, via Larbert, is 69J miles, and the journey occupies from 6.40 p.m. to 8.45 p.m., or 2 hours 5 minutes. By the new route the distance will be 48 miles, with fewer occasions for delay, and therefore the time may be safely taken not to exceed one hour — that is, the day train will arrive at 7.45 instead of 8.45. Thus the east coast journey will be thirty- five minutes shorter than that by the west coast unless the speed of the latter is accelerated. At present the Caledonian is hauling the day express from Carlisle to Edinburgh, 101 miles, in 2 hours, and from Carlisle to Perth, 151 miles, in 3 hours 35 minutes. If the Perth journey were made at the same speed as that to Edinburgh, the time occupied would be three hours, and the odd minutes saved would put both routes on an equality. There ENGINEERING. is not the slightest doubt that this time can be saved, although with difficulty. The entire distance from London to Perth is 440 5 miles by the new east route, and 450 i- by the west route, and this differ- ence of 10 miles is theffotal advantage that the one set of companies holds over the other as regards Perth. To Dundee and Aberdeen there will be a gain of about 10 miles more by crossing the Tay Bridge. If the running of the trains by the two routes be settled by an amicable arrangement between the respective companies, we may assume that the advantage to the east coast route will not be greater than fifteen minutes to Perth and Inverness, and thirty minutes to Aberdeen, while, if it be fought out, both lines will probably run in the same time to Perth. Passengers who are intending to break their journey at Edinburgh will travel by either route; it is only those whose immediate destination is Perth, and beyond, that can possibly be influenced by the opening of the bridge. Imagination fails to conceive what would be the expression of a Conti- nental railway manager if he were asked to spend more than three millions to gain an advantage of this kind. He would regard the mere putting of the proposition before him as an insult to his under- standing, and would find words to express that sentiment very clearly. It would appear absurd to him that he should saddle his company with an enormous annual burden, together with all the ex- penses of a costly struggle, when the matter could be so much more cheaply managed by an agree- ment between himself and the manager of the rival route. It is fortunate for the English public that this way of looking at things does not prevail here, or else we should be much in the same position as our neighbours the French, and should have to pay very high rates for travelling at very moderate speeds. There is one point- worth remembering when we compare our own lines with those in France. Here the company are in absolute possession of their property— they are freeholders. In France the lines are built on 99 years’ concessions, and at the end of that period will have to be surrendered to the State without compensation, just as a leaseholder has to give up his house to the ground landlord at the end of the term. \Ve all know how unpleasant it is to spend money over other people’s property, and possibly this feeling has something to do with Continental railway management. But apart from this there can be no real competition in France, because the country is divided into territories, which are in- violable against the entry of a hostile company. I11 the fewcases where competition exists for foreign traffic even the French railway official cannot resist its influence altogether. The Nord and Est com- panies run some good trains to the St. Gothard in competition with the German Alsace-Lorraine lines, and the latter company runs a good train to Bale, competing with the Paris, Lyons, and Mediterranean line for the Italian traffic. Possibly the day will come when every earthly dispute will be settled by arbitration instead of by fighting, but when it does it will certainly be a bad epoch for the railway traveller. THE NARRATIVE OF THE MANOEUVRES. The Admiralty does not seem to be able to make up its mind as to the form in which it should make the public acquainted with so much of the naval manoeuvres as, in its wisdom, it deems it advisable the public should know. That is little enough this year, for the official “ narrative” recently published is of the baldest description. The official report dealing with the 1887 manoeuvres, which was the first issued, gave a description of the operations, and, in an appendix, an “abstract of reports of casualties to ships employed,” and also a list of casualties to torpedo boats. This was a rare piece of candour on the part of their Lordships ; but one good action, the Laureate tells us, is the stepping- stone to another, and in the following year’s report they carried their virtuous resolutions so far as to take the public into their confidence in quite a friendly way. The report was a lengthy document and contained a vast deal of really valuable in- formation on the state of the Navy. There were “ opinions on the behaviour and sea-going qualities of, or the defects in, the new and most recently commissioned vessels, as obtained from the reports of the admirals in command of the respective squadrons.” These opinions were given by Ad- [Feb. 28, 1890. mirals W. M. Dowell, R. Vesey Hamilton, and F. W. Richards. They contained some most valu- able remarks on the sea-going qualities, &c., of the ships engaged. There was also a digest, by the same authorities, of the report of the Committee on the Manoeuvres. These documents were com- mented upon by the First Sea Lord, Admiral Sir Arthur Hood, and his observations were likewise made public in the report. The exercise of so much candour could not but prove exhausting to a department unaccustomed to its practice ; and we all know that the most enthu- siastic and ardent reformers, after they have breathed the official atmosphere of Whitehall for some time, find their noble aspirations to be dimmed and the fire of their energies to wane. So it has been with the present administration. Like the Rev. Hopley Porter, they have found the burden of so much well-doing too heavy to be borne, and have been glad of an excuse to lapse in the old wicked ways of sin and secrecy. It is sad to see a career so bright in its early promise blighted at its close. Nothing could have been more candid and liberal than the conduct of the present Board of Admiralty in its early days ; nothing narrower than its policy now. This clouding with secrecy is but an ostrich policy, which, after all, defeats its own ends. The public, which pays the bill, is conscious of a light to know what is going on so far as may be com- patible with national interest, that is to say, secrecy ought to be observed only so far as may be necessary to prevent our possible foes learning those things that might be to our disadvantage in time of war. It therefore follows that those things which are made known to foreign naval attaches should not be withheld from the public. This of course has never been the case ; and, indeed, a citizen of the United States has a better chance of knowing many things in connection with the Royal Navy than has a British subject. As an instance of this we may cite the gunnery trials of the Cam- perdown. As our readers are well aware, the public mind was a good deal agitated by the failure of heavy naval guns, and additional interest was there- fore taken in these trials. On the first day when the lighter armament was tried, newspaper re- porters were admitted ; but on the second day, when the heavy guns were put to test, a special order was sent down from the Admiralty that none others than those officially engaged were to be on board. Under these circumstances it cannot be wondered at that the public imagine things are much worse than they are. We have no desire to swell the exaggerated chorus of alarm which has arisen of late on the naval ordnance question. The statements of some of our contemporaries have, to put it mildly, not always been warranted by facts ; but this is not to be wondered at ; jieople naturally imagine things are worse than they are when they find so much trouble is taken to observe secrecy. That is what we mean by an ostrich-like policy ; the Admiralty in its endeavour to escape public censure, buries its head in the sands of secrecy, and thus renders censure more certain. Much the same thing may be said of this present narrative of the 1889 manoeuvres. No reference is made to mishaps to any of the ships engaged, and yet one remembers how full the papers were of them at the time. It would be a plausible argu- ment that “accidents” to Her Majesty’s ships have become so common that they are taken as matters of course ; or that the list was so heavy that the parsimony of the Treasury, of which we have heard a good deal lately, had refused the large sum required for their printing. Some of these accidents were of an unavoidable nature, others were of a trivial description only exaggerated by incident-seeking, picturesque reporters. Others were blameworthy and of a serious kind ; but, had the very worst been levealed, the authorities re- sponsible would not have been brought into such ill-repute as is at present the case, in consequence of the exaggerations made possible only by the secret policy of the Admiralty. Professional officials and naval officers of both branches of the naval service recognise this, and although their mouths are closed in public, in private they resent the action of the Board. It is a pity to see tins de- generacy in an administration that promised so well at its start. It would seem, however, that rapid deterioration is the rule with all Boards of Ad- miralty. However vigorous they are at first, they soon wear out, and it is to be feared that the present one will prove no exception to the rule. In that case the sooner we have a change the better Feb. 28, 1890.] E N G I N E E R I NG. 287 for the naval service, even remembering how disas- trous changes are, and how brief a time vigour and bold action last in a department. The official “narative, ” as we have said, is a bald description of the movements of the ships engaged in the manoeuvres. As the science of naval tactics is not one within our province we do not propose to analyse these movements of make pretend war- fare. There are, however, one or two points worthy of attention. The distribution of intelligence (i.e., movements of the “ enemy”) was arranged on a different plan last year. In 1888, it will be remembered, when Admiral Baird was the defender of Great Britain, his strategy was greatly hampered by the want of information of his “enemy’s” movements. “It is to be observed,” said the official report, “that in the whole course of these manoeuvres the Britsh Admiral was heavily handicapped as being thrown entirely on his own resources. Not only was he cut off from the central source of authentic in- formation — the Admiralty itself — which would not have been the case in war, but the coast defence vessels, to which lie could have reasonably looked for the protection against attack by single cruisers of coast towns, were not utilised.” In the present report we are told that : “It was also proposed to take advantage of the occurrence of the manoeuvres to test the value of a plan — on the necessity of which much stress had been laid — for establishing in London a central office for the receipt of all information relating to the movements of the enemy’s vessels, to sift such information, and transmit any intelligence to certain selected sta- tions for the guidance of officers in command.” This duty was carried out by the Intelligence Department, and afforded the greatest assistance to the defending squadron. The general public are too apt to look on the manoeuvres as a trial of skill between the two admirals in command, and to judge of their respective professional ability in this way. How unjust this is will appear from the instance we have just quoted. Another feature in the 1889 manoeuvres was to test the arrangements for the supplying of coal to fleets operating in home waters. We are not in- formed that these arrangements were successful, and therefore the captious critic is at liberty to conclude they were not so. However this may be, one thing very certain is that no efficient means have yet been devised for coaling ships at sea. In an appendix at the end of the narrative is a list of merchant vessels “captured by the enemy.” As the merchant vessels made no efforts to escape the warships, and the conditions generally were so utterly different to those that would be present in real warfare, not much importance is to be attached to the list. Amongst other points may be noticed the im- portant influence of fog on the results of the opera- tions. Those gentlemen of the dogmatic school of argument, who have cut-and-dried theories on the question of naval tactics and national defence, would do well to remember that, even in summer, fog is a very important factor. The importance of speed is also shown in the way the Hero and In- flexible suffered from the want of it. The value of electric search-lights has been so often questioned of late, some commentators saying they were only likely to prove hurtful to those possessing them, that it is well to notice Rear-Admiral D’Arcy-Irvine attributed the failure of a torpedo boat attack prin- cipally to the continued use of the ship’s search- lights. The Colling wood fell a prey to her pursuers owing to the priming of her boilers, which caused her speed to fall off. Lastly, the want of a proper system of nomenclature is emphasised by the dif- ference of opinion that arose as to the reading of the terms ‘ ‘ protected vessels, belted cruisers, battle-ships, armoured coast defence vessels, and ironclads.” In conclusion, we can only repeat our often- expressed opinion as to the great value of the naval manoeuvres, and trust that they may long continue to be an annual event, and be better reported upon in the future. BRIDGING THE HUDSON RIVER. The great success of the suspension bridge over the East River, that separates New York from the city of Brooklyn, has resulted in the preparation of plans for a larger bridge on the western side of the city, passing over the Hudson River and con- necting New York with Hoboken, New Jersey. New York is built upon an island, and has rail- way communication only upon the north. For many years a tunnel under the Hudson River has been driven at various rates of progress, and for a long time the work was at a standstill. The bridge scheme of Gustav Lindenthal, C.E., consists of a link 6500 ft. in length, and involves an enormous structure with 2850 ft. in a single span, and con- taining six railroad tracks. The plan, as far as can be stated to the public, involves four steel wire cables, each 4ft. in diameter and 50 ft. apart, and forming the upper chords of the bracing trusses. The towers would be of open lattice construction and not of masonry. The estimates for this mammoth structure are naturally of corresponding dimensions ; the figures for the bridge being 16,000,000 dels., approaches, 7,000,000 dols., and the right of way from 11,000,000 dols. to 13,000,000 dols. At present all freight from the west which is not delivered by the New York Central Railway, and enters the north of the city, is delivered at the western side of the Hudson River and then shipped upon lighters which are towed to the pier nearest to their destination. If this bridge were built there would still remain the question of breaking bulk and moving by land to the several points of delivery ; so that without questioning for the present the great utility of such a bridge, the cheapness and convenience of a water transport, which goes so far towards the final distribution of freights, would still remain a permanent method of delivery and prevent any bridge from becoming a monopoly in transportation, except so far as delivery at the eastern terminus of the bridge or such points near it, as would render this a cheaper method in such instances. NOTES FROM THE SOUTH-WEST. North’s Navigation Collieries (Limited). — The report of the directors states that the net trading profits for the past year were 50,057 1. 9s. 7cl. An interim dividend at the rate of 10 per cent, per annum was paid in August last for the first half of the year ; and after writing off 4000k towards meeting renewals and depreciation, the directors recommend a dividend for the second half-year at the same rate, making 10 per cent, for the entire year, free of income tax. This will leave a balance of 0057k 9s. 7d. to be carried forward, subject to auditors’ remuneration, which the shareholders will be asked to vote at the general meeting. A sum standing to the credit of special account in the previous balance sheet, viz., 23,501/. 10s. 5d., is being expended in the development of the company’s properties, pursuant to a resolution of the last general meeting. The sinking of two new pits has been com- menced, and will be pushed on with vigour immediately. A branch railway connecting them with the main line is completed. Cardiff. — Steam coal has been in good demand at fully former rates ; the best descriptions have made 15s. 3d. to 15s. (id., and secondary qualities 14s. 9d. to 15s. per ton. There has been an active demand for house coal; No. 3 Rhondda has made 15s. (id. to 15s. 9d. per ton. Patent fuel has been firm, and iron ore has continued m good demand. Shipments of finished iron and steel from Car- diff have shown some falling off of late, but previous prices have been supported. Heavy section steel rails have made 7k to 7k 10s., and light section ditto, HI. to 8/. 10s. per ton. Bart •>/ Docks and Railway. The directors of this com- pany recommend a dividend for the past half-year at the rate of 51; per cent, per annum. The Pontypridd section has been taken over by the company. Great Western Cotton Company (Limited). — The direc- tors state that, owing to losses resulting from a strike at the works, they are unable to declare an interim dividend for the half-year ending 81st December last. The strike, they add, terminated towards the end of the year, and the works have since, been in active operation. The interim dividend for the corresponding half of 1888 was at the rate of 31 per cent. The Great Western Railway at Bristol- The Great Western Railway Company is proceeding with the con- struction of a relief line between Stapleton -road and Laurence Hill Station, near Bristol. This relief line, has been rendered necessary by the great increase of traffic for South Wales and the North, caused by the opening of the Severn Tunnel. It is, in fact, part of the great tunnel scheme, but was put off till the traffic developed sufficiently to warrant its being carried out. Cyfarthfa.—A. fourth blast furnace and three addi- tional stoves are now in progress and will shortly be brought into operation. Wages in Wales. —At a meeting of the joint sliding scale committee for South Wales and Monmouthshire on Saturday, the accountants’ report as to the price of coal was presented, and it was decided that there should be no alteration in the rate of wages. Pcntyrcli.- The Pentyrch Iron Works were recently acquired by a Leeds firm for the purpose of converting them into mills for the production of tinplates. Arrange- ments are now so far completed that a number of men are engaged in preparing for tire erection of eight tin mills. The alterations will be carried out under the supervision of Mr. B. Rees, Treforest, who has been ap- pointed manager of the new undertaking. Torquay. — New harbour works at Torquay, upon which the local authorities are proposing to spend 50,000/., have been commenced. The railings in front of Cary- green have been removed, and the work of reclaiming that portion of the land from the sea is to be proceeded with at once. Dredging will be rapidly carried on and subsequently a concrete pier will be taken in hand. Mangotsfield. — A company will be shortly formed with the view of further developing the coalfields in the Man- gotsfield district. The coal raised from the fields is spoken of favourably. Llancaiach. — The Ystrad Mynach Valley Colliery Company has acquired an extensive area between Llan- caiach and Ystrad Mynach, and is about to commence sinking a pit in search of the Mynyddislwyn vein of house coal on a site near the old Tredowen level, along- side the Penallta branch line of the Rhymney Railway. A contract for sinking a trial pit has been let to Mr. R. Davies, of Maesycwmmer. North Wedcs Coed Trade. — A meeting of North Wales colliery proprietors was held on Monday at Chester to consider a notice given by the colliers for an advance of 10 per cent, from March 1. The proprietors decided that the state of trade did not warrant the demand, and were unanimously in favour of a scheme of federation, which was submitted to. Lundy Island. — A meeting of the executive of the Bristol Channel Ports Committee was held at Bristol on Thursday, Mr. A. J. Lawson presiding. The chairman reported that the memorial of the committee to the First Lord of the Admiralty had been duly presented and acknowledged. It briefly stated that the harbour of refuge at Lundy Island would be desired as a basis of operations for the portion of the fleet which might be employed in guarding the St. George’s and Bristol Channels, as a fortified station, and as a port of repair for Her Majesty’s ships ; but after full examination of all the conditions their lordships stated that they were of opinion that Lundy Island did not offer the Navy more advantages for defensive purposes than was already at the disposal of the fleet in Milford Haven, where there was a natural harbour strongly fortified, and provided with the establishments for the construction and repair of ships. Milford Haven. — The half-yearly meeting of the Milford Docks Company was held in London on Thursday, Mr. T. Wood presiding. The chairman, in moving the adoption of the report of the directors, stated that the proposed Canadian line of steamers would be shortly brought before the public. The fish trade at Milford, the chairman added, was steadily increasing, and a vessel had been recently chartered to convey coal from Milford to Singa- pore. The directors’ report was adopted; and the meet- ing having been made special, approval was given to a Bill now pending in Parliament authorising the Board to create additional debenture stock to an extent not ex- ceeding; 150,000/., to be applied to the construction of a pier and other objects. NOTES FROM SOUTH YORKSHIRE. Sheffield, Wednesday. The Coed Crisis. — An effort is being made in this dis- trict to bring about an understanding between the federations of the eoalmasters and men with a view to the prevention of the threatened strike of miners. A well- known mining engineer is acting as pioneer in the nego- tiations. Notices of the men are being given in and there is much excitement in the district. The Yorkshire Miners’ Association report that nearly all the leading lodges in the county have held meetings to test the feel- ings of the men respecting the application of funds in the event of a strike taking place. The resolution sug- gested by the Hoyland Silkstone Lodge, and passed by the council — that in the event of a strike taking place the funds of the Association shall not be touched until the third week of the struggle — has been thoroughly tested. The reports which have come to hand show that the lodges are almost unanimous on the point. Heavy Forging Press. — Messrs. Vickers, Sons, and Co. (Limited) it is stated, intend to erect a second forging press for the heavy work which they have gone in for so extensively in marine and military material. The new press, which will take a considerable time to complete, is to have a capacity of 0000 tons. Midland Counties Miners' Permanent Relief Fund. - The tenth annual meeting of the Midland Counties Miners’ Permanent Relief Fund has been held. The annual report showed that the year commenced with 3569 mem- bers and 32 branches, and closed with 4228 members and 32 branches, an advance of 659 members on the year. The receipts from members had been 2257/., and from other sources 491/. A sum of 1050/. was now invested, and the balances in hand amounted to 726/. 7s. Id., a total of 1776/. 7s. Id., being an increase in value on the year of 546/. 12s. 7d., against 232/. 11s. lOd. saved last year. Colliery Extensions at Rotherham. — A valuable and ex- tensive addition to the coalfields of Messrs. John Brown and Co., Limited, has just been made with the object of establishing a steam coal colliery within easy reach of .Sheffield. Land situate at Canklow, and adjacent to the Masbrough and Chesterfield branch of the Midland Rail- way, has been secured from Mr. Fullerton, of Thrybergh Hall, Rotherham. Two shafts are to be sunk and plant for dealing with an output of from 1500 to 2000 tons per day is to be put down. The machinery and appliances are to be of the most approved kind. 238 Large Machine Orders. — A well-known firm in Leeds have just sent a large plate mill, weighing upwards of 500 tons, to the steel works in Bilbao, for which they made the whole of the Bessemer plant and compound rolling mill engines. This means that a considerable quantity of plates will now be rolled in Bilbao instead of being purchased in England, as heretofore. A heavy forging press for the steel works at Terni, in Italy, has also been delivered. Coke. — The coke trade shows no falling off. The out- put of the district is large, having for some time been augmented weekly by the lighting of additional ovens. More coke will shortly be wanted for Northamptonshire, where an additional furnace belonging to the Hunsbury Hill Iron Company, will shortly be started. The increase in the tonnage rates, added to the increase in the price, is being seriously felt by large consumers. NOTES FROM CLEVELAND AND THE NORTHERN COUNTIES. Middlesbrough, Wednesday. The Cleveland Iron Market. — Yesterday there was only a poor attendance on ’Change, and not much business was done, but prices were a little better than they have been during the past day or two. Warrants have been falling pretty rapidly recently, and this has almost altogether put a stop to buying, but yesterday improved somewhat and buyers were rather more inclined to do business. They offered 52s. fid. for prompt f.o.b. delivery of No. 3 g.m b. makers’ iron, but sellers as a rule would not do business under 52s. 9d. For March delivery of No. 3 it was stated that 53s. had been paid, and for April delivery 53s. fid. was the quotation. Makers, however, who gave any quotation at all, asked considerably higher rates than the above, none of them being willing to book new contracts under fiOs. for early delivery of No. 3. They are still pretty well supplied with orders, and are confident that we shall soon see better prices. Grey forge iron is still dearer than No. 3, and 55s. fid. to 5Gs, has to be paid for this quality. Yesterday, Middlesbrough No. 3 warrants opened at 51s. lid., but they soon rose to 52s. 3d., and at the close of the market there were buyers at52s. 4* d . cash, while some holders would not part with any Cleveland warrants under 52s. fid. Hematite warrants closed at G4s. ca ll, but merchants here would not sell makers’ iron at less than 73s., and producers asked more than this figure for mixed numbers. It is not expected that the Cleve- land Ironmasters’ Association returns for the month of February will show any material increase in makers’ stocks. To-day the market was flat and business was practically at a standstill. Prices fell and buyers were not to be found at all. There were merchants who quoted No. 3 g.m.b. Cleveland pig iron 52s. fid. for prompt f.o.b. delivery, but 52s. 3d. would have been taken for that quality. Middlesbrough No. 3 warrants fell to 51s. lOd. cash, and the business that was done was in warrants, people in want of iron preferring to take it out of stock, when they can buy it cheaper that way than any other. Manufactured Iron and Steel. — There is little new to report in the finished iron trade. Producers continue busy, but inquiries concerning new orders are very few. There is no disposition to buy, nor is there any likely to be until the pig-iron trade is a little steadier. Common bars are quoted 71. 10s. ; ship-plates, 71. 10s. ; and ship angles 71. 5s., all less 2£ percent, discount for cash. The steel industry is very quiet and prices are not quite so firm as when we last reported. Heavy sections of rails are obtainable at 61. 10s. per ton ; ship-plates are 81. 10s. ; and ship angles 81. 5s. The Wear Steel Company (Limited). — The Wear Steel Company (Limited) have issued their first report. It states that the profits made during the last three months of the year (in which the works were started) have been used to partially wipe off the expense incurred in the formation of the company. The balance-sheet shows that the works up to date have cost 133, 2G6/. 7s. 9d., this sum being 33,260/. 7s. 9d. in excess of Mr. Beardmore’s original estimate. The following is a statement of finan- cial affairs up to 31st December. Capital and liabilities : Nominal capital, 12,000 shares of 10/. each, 120,000/. ; issued, 11,400 shares on each of which 9/. is paid, 103,179/.; mortgage debentures, 50,0001. ; creditors on open accounts, 19,736/. 3s. 8d.; on bills payable, 1032/. 0s. lid ; deben- ture interest, 1292/. 8s. Id.; Woods and Co., 1506/. 15s. 7d. ; total, 23,507/. 8s. 3d ; gross total, 170,746/. 8s. 3d. Under the head of property and assets are the following items : Land, 17,843/. 15s.; buildings and cottages, 18,898/. 5s. lid.; fixed plant and machinery, 91,765/. lfis. (id.; loose plant and tools, 4758/. 10s. 4d. ; total, 133,260/. 7s. 9d. ; stocks as per valuation, 30,482/. 4s. 9d. ; book debts as per ledger accounts, 12,300/. 6s. 2d.; cash and bills, cash on hand, 270/., and bills on hand, 427/. 9s. 7d.; total, 176,746 /. 8s. 3d. NOTES FROM THE NORTH. Glasgow, Wednesday. Glasgow Pig-Iron Market. — Last Thursday’s pig-iron market was characterised by a quiet tone. The large reduction in the stocks of iron in the warrant stores on the preceding day, combined with the reduction in the Bank rate, had but little effect on the market. Scotch iron did not vary in price more than 2d. per ton duiing the whole day* but the closing quotation showed an im- provement of Id. per ton over the previous day’s final quotation. Cleveland iron was depressed, the price at one time being 10?,d. per ton down, but the closing quota- tion was still Is. lid. above that of Scotch iron. Hema- tite iron was firmer, and improved 4-Id. per ton. The closing setthment prices were — Scotch iron, 53s. 9d. per ENGINEERING. ton ; Cleveland, 54s. 10£d. ; hematite iton, 67s. 10 id. per ton. The indifferent reports received regarding the con- dition of the iron trade in the Midlands, and the reduc- tion in prices announced in Birmingham on Thursday, were reflected in the Glasgow market on Friday by a relapse in the prices of warrants. There was a preponder- ance of sellers, and a fair amount of scrip very soon changed hands. Prices in the forenoon dropped about Is. per ton from the top, Scotch iron being 9d. down from Thursday’s close, Cleveland Is. 3d., and hematite iron Is. per ton down. In the afternoon there was renewed selling, and prices suffered a further drop. At the close the settle- ment prices were — Scotch iron, 52s. 7id. per ton ; Cleve- land, 52s. 9d. ; hematite iron, 65s. 9d. per ton, the decline on the day being respectively Is. l^d., 2s. lid., and 2s. ljd. per ton. Under ordinary circumstances the with- drawal of nearly 10,000 tons of pig iron from the warrant stores within a week would have given an extra filip to business, and prices would probably have advanced a shilling or two per ton. The reverse happened on Mon- day forenoon, the price of Scotch iron falling Is. Id. per ton, while Cleveland and hematite were down in price respectively Is. 2d. and 2s. fid. per ton on Friday’s closing prices. The unfavourable reports from America and the Continent, together with the absence of buying orders from outsiders, gave “bears” an opportunity of which they took full advantage by depressing prices. The after- noon market was also flat but steadier if anything at the close. The settlement prices at the close were — Scotch iron, 51s. 7id. per ton ; Cleveland, 51s. lOld. ; hematite iron, 63s. 4id. per ton ; so that the decline over the day was respectively Is., 10Jd., and 2s. 5d. per ton. There were heavy settlements, but no failures were reported. After the severe drop in prices and excitement of Monday’s market, yesterday’s was characterised by a firmer tone. Scotch iron had a steady recovery to the extent of 4d. per ton, while Cleveland and hematite prices recovered, respectively, (id. and 8d. per ton. The differences pay- able on business done during January at one month have been gradually becoming less severe. Early in February as much as 12s. fid. per ton was paid as differences on Scotch iron transactions early in January, 13s. fid. on Cleveland iron, and 18s. on hematite iron. The differ- ences on Monday were reduced to 7s. per ton on Scotch iron, fis. on Cleveland, and 10s. on hematite iron, and in the corresponding week of last month prices came down smartly, thus reducing the differences further. The closing settlement prices were, respectively, 52s., 52s. 41d., and 64s. per ton. The market was feeble this fore- noon, and Scotch warrants receded in price to 51s. 8d., being a decline of 4d. for last night’s close ; Cleve- land was at least 4d. per ton lower, and hematite iron fully 3d. per ton lower in price. In the after- noon prices receded still further, but less in the case of Scotch iron than in Cleveland and hematite. During the past week four furnaces making ordinary iron were relighted at Carnbroe Iron Works, while one hema- tite furnace was put out of blast at Gartsherrie, and one ordinary at Shotts Works, leaving a total of 89 now in blast, as compared with 80 at this time last year. Last week’s shipments of pig iron from all Scotch ports amounted to 6497 tons, as compared with 7152 tons in the corresponding week of last year. They included 600 tons for the United States, 205 tons for South America, 270 tons for Australia, 300 tons for Italy, 425 tons for Ger- many, 405 tons for Holland, 505 tons for Belgium, smaller quantities for other countries, and 3607 tons coastwise. The stock of pig iron in Messrs. Connal and Co.’s public warrant stores stood yesterday afternoon at 875,587 tons, as compared with 886.277 tons yesterday week, thus showing for the week a decrease of 10,690 tons. Cessation of the Ferry Traffic at Burntisland. — The adverse effects which the opening of the Forth Bridge for railway traffic is certain to produce upon the trade and population of Burntisland are already being revealed. The North British Railway Company have intimated to the workmen connected with the ferry that on and after March 5 the transit of goods and minerals by the ferry steamers will be stopped, and all through goods are to be sent via the Forth Bridge, Inverkeithing, and Thornton. The direct effect of this change will be the throwing out of employment between 80 and 100 of the workmen. At present there are four steamers en- gaged in the carrying of goods across the Forth, and for the working of these there are double crews required, as the steamers are run night and day. In addition to the crews of the vessels, and a number of men who are em- ployed in marshalling the wagons and running them on board the steamers, the majority of the engine drivers, firemen, cleaners, and guards who are employed in run- ning the goods trains, will require to remove elsewhere. The passenger ferry service will be continued for a month or two longer ; but so soon as the Inverkeithing and Glenfarg lines are completed there will be another batch of railway servants cleared out of Burntisland. It is computed that before the summer sets in about 200 rail- way workmen will require to leave the town. Shipments of Machinery, tic., from the Clyde. — The foreign and colonial shipments of machinery, &c., from the Clyde reported last week, included the following : Machinery of various kinds, of the value of 8700/., chiefly for Calcutta, Colombo, Rangoon, Japan, Nantes, Barce- lona, New York, Boston, and Rouen ; sewing machine parts, valued at 8285/., chiefly for Nantes, Bordeaux, Rouen, Cadiz, and Barcelona ; blooms, billets, plates, bars, and other steel goods, of the value of 9900/., chiefly for Rangoon, Japan, Halifax, Buenos Ayres, Boston, Calcutta, Bombay, and Adelaide ; pipes and other cast- ings, plates, sheets, bars, tubes, sleepers, and miscel- laneous iron manufactures, of the value of 10,610/. Shipbuilding and Engineering. — Messrs. Murdoch and Murray, shipbuilders, Port-Glasgow, have secured a con- [Feb. 28, 1890. tract to build two steel screw steamers each of 175 ft. keel and 500 tons gross register. The vessels are in- tended for the fruit trade between the West Indies and America, and they will each be supplied with triple- expansion engines of 800 indicated horse-power. Accom- modation will also in each case be provided for about sixteen first-class passengers. A contract has been placed with Messrs. William Simons and Co., Renfrew, for a set of powerful sand-pumping apparatus, which is to be fitted to one of the steam hopper barges built by the firm some time ago for the Mersey Docks Board, for the improvement of the channel across the Mersey bar at Liverpool. Institution of Engineers and Shipbuilders in Scotland . — An ordinary meeting of this Institution was held last night, at which the principal business was the reading of a paper — the last of the series — on “The Forth Bridge,” by Mr. A. S. Biggart, C.E., Mr. Arrol’s leading right- hand man in carrying out his many remarkable inven- tions in constructional devices. This paper had reference to the erection of the superstructure of the bridge, and more especially the central girders. MISCELLANEA. Chicago has succeeded in getting Congress to fix on her as the site for the proposed World’s Fair in 1892. This will be a great disappointment to New York. The Iron Age states that there are about 1100 canals for irrigation purposes in Colorado. The primary canals are upwards of 6000 miles in length, whilst the secondary system is still longer. Upwards of 4500 square miles of land are fed by the system. At the meeting of the Institute of Marine Engineers, held on the 18th inst., in the Langthorne Rooms, Strat- ford, E., the discussion on Mr. Sommerville’s paper on “ Ventilation and Heat Radiation,” read at the previous meeting, was resumed. The gross receipts of the 23 principal railways in the United Kingdom, for the week ending February 16, amounted, on 10,1421 miles, to 1,208,388/., and for the corresponding period of 1889, on 16,030 miles, to 1,131,962/., an increase of 1121 miles, or 0.7 per cent., and an increase of 76,426/., or 6.7 per cent. An Engineers’, Electricians’, Builders’, and Iron- mongers’ Exhibition is to be held in the Royal Agricul- tural Hall, Islington, on March 17 to 29, 1890. Any one interested in these professions and trades will receive a ticket admitting to the Exhibition on sending a post-card to the offices, 43, Oxford-street, W. C. It has been decided to keep a record of the number of visitors ascending the Monument. The City architect has accordingly instructed Messrs. Le Grand and Sut- cliffe, of London, to erect a set of Norton’s turnstiles. The port boiler of the new third-class cruiser Barra- couta, which is lying at Sheerness Dockyard, was examined for the fourth time on Tuesday by the experts appointed by the Coroner’s Court, the Admiralty, and the Palmer Shipbuilding Company. Nothing was dis- covered to account for the serious accident which occurred at her recent steam trial, and the experts have now decided to have the boiler filled with water and subjected to a water test with the view of ascertaining whether it is in a perfectly sound condition. The boiler was tested with water before leaving for the trial, and everything was then found perfectly satisfactory. From some experiments by Mr. James Macbeth, of the West Shore Railroad of the United States, it would appear that the average American expressengine drawing a train of seven cars at 42.88 miles per hour uses 47.431b. of coal per train-mile. The engine experimented on had an extension front, a grate area of 18 square feet, the boiler being lift, long, with 240 1-in. tubes. The cylinders were 18 in. by 24 in., the coal used about 6 per cent, of ash and clinker, and the evaporation was 6.28 lb. of water per pound of coal. A ten-wheeled freight engine was also tested whilst hauling a load of forty cars at an average speed of 20 miles per hour. This engine had cylinders 18 in. by 24 in., and the coal consumption in this case reached 106.601b. per car-mile. The Mines Department of the French Ministry of Public Works has published particulars as to the produc- tion of coal last year, the figures showing that the total output was 24,588,880 tons, or 1,985,986 tons more than in 1888, and 3,300,000 tons more than in 1887. This increase would have been still larger but for the strikes which occurred during the past year in the basins of the Pas-de- Calais and the Nord, which produced 13,456,000 tons last year, or more than half of the whole of France. This represents, despite the strikes, an increase of over a million tons upon 1888, while it is of interest for English coal- owners to mark that, despite the iron crisis in the southern departments of the Gard, the Tarn, the Aveyron, and the Hirault, the output of coal has increased from 3,000,000 to 3,500,000 tons, a great effort being made by the southern companies to increase their sphere of action and supply the Mediterranean ports which have hitherto been provided chiefly with English coal. The Royal Show at Plymouth. — We are requested to draw the attention of intending exhibitors to the fact that the entries in the implement department close on the 1st of April next, and the entries of live stock, poultry, and pi’oduce on the 1st of May. The forms of entry for implements, horses, bulls, cows, sheep, pigs, poultry, w'ool, cheese, butter, cider and perry, jams and preserved fruits, hives and honey, and for the butter-making and horse-shoeing competitions, are now ready, and copies will be forwarded by the secretary on a specific request being addressed to i2, Hanover-: quare. ENGINEERING, February 28 , 1890 . THE FOR' PLATE III. H BRIDGE. INCH QARVIE PIER — 260 '. — — mo 1 0 NORTH QUEENSFERRY PIER -~--l45'-* £89'. 9 "... ‘ !i'i ! 1200 1400 1000 1800 2000 2100 2400 2600 2800 3000 Ft G i r d e r s Pig-21. 4 t Fig.23. Id t fe e aada lay 5. abend of Bay 5 at upper portion of Bay 6. ENGINEERING, February 28, 1890. PLATE V. THE FORTH BRIDGE. GENERAL VIEW OF SITE LOOKING NORTH-EAST. CAISSONS BUILDING ON LAUNCHING WAYS, ENGINEERING, February 28, 1890. VIEW FROM INCHGARVIE CASTLE. THE SOUTH CAISSON IMPOSITION. ENGINEERING, February 28, 1890. THE FORI launching of caisson for south-west pier, inchgarvie. PLATE VII. GENERAL VIEW OF SITE, WITH PIERS OF SOUTH APPROACH VIADUCT, LOOKING NORTH, CAISSON FOR QUEENSFERRY NORTH-WEST PIER. CONSTRUCTING TIMBER CASING ROUND THE TILTED CAISSON. NORTH APPROACH VIADUCT : RAISING VIADUCT GIRDERS. NORTH APPROACH VIADUCT ; GIRDERS RAISED TO FULL HEIGHT FRONT VIEW OF NORTH CANTILEVER END PIER AND VIEW OF VIADUCT AND ARCHES. ENGINEERING, February 28 , 1890 . V •b ENGINEERING, February 28, 1890. THE FOR' FIFE PIER. ERECTION OF SUPERSTRUCTURE ; CONSTRUCTION OF LIFTING PLATFORMS. FIFE PIER. ERECTION OF SUPERSTRUCTURE ; LIFTING PLATFORMS ABOUT 100 FT. ABOVE HIGH WATER. PLATE IX. BRIDGE. INCHGARVIE PIER. ERECTION OF SUPERSTRUCTURE ; RIVETTING CAGES ANI» HYDRAULIC RI VETTING MACHINES ON VERTICAL COLUMN AND DIAGONAL STRUT. ENGINEERING, February 28, 1890. QUEENSFERRY PIER, LOOKING NORTH. LIFTING PLATFORMS ABOUT 190 FT. ABOVE HIGH-WATER LEVEL. ENGINEERING, February 28, 1890. QUEENSFERRY REEK, LOOKING NORTH. PLATFORMS RAISED TO FULL HEIGHT. FIFE PIER. BUILDING OF TOP MEMBERS ON PLATFORMS. COMMENCEMENT OF BUILDING OUT BOTTOM MEMBERS IN CANTILEVERS, AND SHOWING TEMPORARY SUPPORTS. i FIFE FIEK, LOOKING .SOUTH. PLATFORMS RAISED TO FULL HEIGHT. FIFE PIER. PLATFORMS RAISED TO FULL HEIGHT. ENGINEERING, February 28, 1890. PLATE XII. FIFE CANTILEVEK. SIDE ELEVATION, LOOKING EAST, ■ • ENGINEERING, February 28, 1890. EFFECT OF SEA FOG. CENTRAL TOWERS AND SOUTH APPROACH VIADUCT. ENERAL VIEW OF CENTRAL TOWERS AND APPROACH VIADUCTS LOOKING NORTH. PLATE XIII. B R I D G F. * - H.M.S. “DEVASTATION” PASSING THE FIFE PIER. ■ - QUEENSFERRY PIER. INTERSECTION OF DIAGONAL STRUTS, WITH HORIZONTAL AND DIAGONAL BRACING GIRDERS, INCHGARVIE PIER. RI VETTING IN TOP MEMBERS BETWEEN VERTICAL COLUMNS. ENGINEERING, February 28, 1890. ' ENGINEERING, February 28, 1890. THE FOR' FIFE PIER. FIRST HALF-BAY IN FIXED CANTILEVER, SHOWING LIFTING PLATFORM FOR BUILDING THE LOW'BR PORTION OF BAY TOP MEMBER CRANE WITH TLATFO-RM SUSPENDED FROM IT. AND PLATE XV. BRIDGE. I ENGINEERING, February 28, 1890. PLATE XYI. Q.TJP.BNSPEKBY PIER ; HOBIZONTAl AND DIAGONAL BRACING GIRDERS ; PART OF INTERNAL VIADUCT AND TEMPORARY STAGING TJEENSFERRY PIER. INTERNAL VIADUCT FROM CENTRE OF BAY TO WITHIN CENTRAL TOWERS. * ENGINEERING, February 28, 1890. THE for: ♦ PLATE XVII. U BRIDGE. FIFE PIER. CENTRAL TOWER AND LOWER HALF OF FIRST BAY IN FREE CANTILEVER. ENGINEERING, February 28, 1890. THE FOR: PLATE XVIII. I BRIDGE. >ER COMMENCED ; FIXED CANTILEVER NOT QUITE COMPLETED. ENGINEERING, February 28, 1890. THE FOR. QUEENSFERRY PIER AND INCHGARVIE SOUTH CANTILEVER, WITH PARTS OF CENTRAL GIRDER BUILT OUT. INCHGARVIE SOUTH CANTILEVER, WITH FIRST BAY OF CENTRAL GIRDER BL'ILT OUT, >J PLATE XIX. H BRIDGE. — , — w ’ - . , . . • ■ ' ■ ® . m * * ■ . ■ ■