1 I 1 '7-^^t V SHIP'S LIBRARY, U. S. S. VICKSBURG. Class Book Digitized by the Internet Archive in 2011 with funding from The Library of Congress http://www.archive.org/details/deepseasoundingdOOusco < tll^ITED STATES COAST AE^D GEODETIC SURVEY CARLILE P. PATTERSON STJPEKIXTENDENT DEEP-SEA SOUNDING AND DREDGING A DESCRIPTION AND DISCUSSION OF THK METHODS AND APPLIANCES USED ON BOARD THE COAST AND GEODETIC SURVEY STEAMER, "BLAKE" By CHARLES D. SIGSBEE LIi:UTEXAXT-C(»nrANDEl{, r. S. XAVY ASSISTANT IN THE COAST AND GEODETIC Sl^RVEY WASHINGTON O V E R X M E X T P K I X T I X ( i OFFICE 1880 N,.> (^A" w^^of^r NOTE BY THE SUPERINTENDENT. OFFICE OF THE U. S. COAST AND GEODETIC SURVEY, Washington, D. C, March 15, 1880. This volume on Deep-Sea Sounding and Dredging lias resulted from the work executed during the past few years, mostly in the Gulf of Mexico. To show the char- acter of that work the following extract from my Annual Report of the Progress of the Coast and Geodetic Survey for the year ending June 30, 1879, is given. ■•The deep-sea suuiidiuiis tlirouohcit the (iiiifof INIexi.-i,. jiaits ,,f the ( 'mihl.eiu, Sea. an, I ehaiiiiels anniiul Cuha. witli serial teniperature „l,servati.ms tVoii, sinfaee t,, holtnai and ,,l,s.rvatin,,s ,,t rmTents. are beginning to yield valuahle results towards a ni.ir,- deHiiite eoiireption of the How. mass, and dil'eetion of the Gulf Stream. •• The i.rohlem of the Gulf Stream has heen one of the principal studies of this Survey, hut for several years before the war, during the war. and for several years after, tin- want of means and suitable vessels sus- pended its investigation. After the data prevh.usly secured, those to he obtained were: I. Depths thr..ughout the Gulf of Mexico and the Gulf <,f Fh.riila. II. Temperatures from surface to h(,ftom over the same area. III. Character of bottom throughout the same area. IV. Specimens of water for analysis, from .surface to bottom, throughout the same area. V. Surface and un.ler Currents. VI. Aidnial life from surface to bottom, especially at the latter. -After all the data have been obtained in reference to the waters forming the Gtdf Stream, including those of the Gulf of Mexico and the Atlantic east of the Caribbean islands, the Stream is tii be followed to its con- dusions. Its oscillathms of position, ditferences ,,f velocity, m.mthly and annual, and im-rease <,f volume north ■•Congress having l)artially provided means, the w.,rk of ..btaining data under the first tive heads was begun in 1^72 in the (Julf of Mexico, by Conuuander .T. A. Howell. V. S. N., A.-^sistant Coast Survey, commanding successively the steamers -Bache- and •Blake.' Howell su,a-essfully ran seven hundred and fbrty miles of sounding lines from shore out to depths of l.-20(l fathoms, by the old methods, obtaining tin- collateral data. ••Sir AVilliam Thomscm's wire sounding apparatus having been successfully used, in tl,e PaciH,- in .lepths Coast Survey. At this tinn- Commander Howell was transferred to other- duty. lb- was sur,eede,l in the com- mand of the 'Blake' by Lieutenant-Counuand.-r C. D. Sigsbee, V . S. X.. Assistant Coast Survey, and hy that officer the deep-sea soundings (generally beyond one hinulred fathoms and to the depths of 2,119 fathoms) of the ^vhole of the Gulf of Mexico were completed. He obtained at the same time full data under the first Kve head- -1- iS'OTE BY THE SUPEKINTENDENT. iiigs named. WIumi Sigslu'e saw the Tliomsqn wive sounding apparatus, he at once suggested important improve- ments, and devised ackhtional apparatus to relieve the strain on the wire dui'ing violent and rapid movements of the-small vessel. He also made other improvements so givatl.v facilitating the work that in 2,000 fathoms' depth the 'Blake' (of three hundred and fifty tons N. M.) was enahled. in nearly all \veatliers, to sound and obtain serial temperatures continuously day and night, witli a probable error in sounding not exceeding one-quarter of one per cent, of the depth, even during moderately severe gales. "The number of nautical miles of sounding-lines run by Sigsbee in the Gulf, with serial temperatures, was 12,766.* This gi'eat woi'k was, by the energy and unintermitting labor of Lieutenant Commander Sigsbee, eai'nestly supported by the officers and crew of the ' Blake,' completed early in the summer of 1878. The remaining part of the work; viz., collection of specimens of animal life from surface to bottom, was yet to be '■As naval officers are professionally neither naturalists nor geologists, I sought the services of Prof. Alexander Agassiz, who consented to take charge of this special part of the work, requiring only the outlay needful for his daily expenses. From his great experience with wire rope in mining operations. Professor Agassiz proposed its use for dredging purposes. Lieutenant-Commander Sigsbee, after conference Avith Professor Agassiz and myself, and to meet the requirements of the work hi every way, thoroughly fitted the 'Blake' for dredging and other piirjioses. "Professor Agassi/, joined tlie -Klake' at Havana in December, 1877, when Lieutenant-Connnander Sigsbee at once began a series of divdgings in the Gulf of ]\[exic(,, over groun.l indicated by Professor Agassiz, who viewed as they came from the wat.'r, took cliarge of and i)reserve(l tlie -Knds' of each haul of the dredge and tangles. The nets, dredgvs. Ac. had 1 ii made tV.mi tlie best models formerly u.sed in researches abroad, but some, not proving initirely successfu), were, at tli<- tii'st failure of each, made completely successful by sug- gestions from Lienteiiant-Cominamlei- Sigsbei", I'rofessor Agassi/,, Lieutenant Ackley, Master Jacoby, mid other otticers of the vessel. ■■Pi'dfessor Agassiz was ol.liged to return home I'arly in March. ]H7H. A few successful hauls of the dredge were made after his d.'|,artiire. Lienteiiant-C'omiiiiind.-r Sigsbee in the ^ Blake ' continued, with his usual energy, until .luiie, adilitioiial woik- of sdiiiidings. serial tciii|icratu]'('s, Ac, under my special instructions. "The experience .if tliat season suggested to Lieutenaiit-Cominander Sigsbee many improvements of tlie machinery and facility's for dre.lging, and also an improved dredging accmnulator of his own design for rehev- ing tin- strain on tlie dredge rop.'. I'nder his special directions and in accordance with his plans the 'Blake' was ciinqiletely letifted with new reeling-engine, dredging-engine, sounding apparatus, &c,, for all the varied classes of work of deep-sea somiding, dredging, &c, '■ The term of service of Lieutenant-Commander Sig.sbee on the Survey having expired, he was relieved in the command of the ' Blake ' by Commander J, E. Bartlett, l^. S. N., Assistant Coast and Geodetic Svu-vey, hi November, 1878. " The discovery by the ' Cliallenger ' of submarine lakes, \vhose temi>eratures are constant to the greatest depths with that of the ocean at the depths of their rims, rendei-ed it more than ever imperative to determine the depth of the rims separating the waters of the Gulf of Mexico from tliose of the Caribbcini and its waters from those of the Atlantic, both to the eastward and nortliward. I assigned the 'Blake- f<,r this development, and Professor Agassiz again accompanied the vessel to cai'e for his own class of the work. As he was obliged to return home hi March, 1879 (the 'Blake' having left Washington November 28, 1878), the first work done was, of course, the dredging. Commander Bartlett effected this with many successful hauls, at localities indicated by Professor Agassiz, in depths of from ten to 2,450 fathoms, all — officers, naturalists, men — working in harmony, with the necessary result — complete success. Of course the dredging operations of the vessel were conducted by «This Is exclusive of 219 miles of inshore sounding-lines and 1,800 miles of dredging-lines in the Gulf of Mexico, and 2,06.5 miles of sounding-lines in the Gulf of Maine, XOTE BY THE SUrERIXTENDENT. O the officers and crew iiiuler the trireetion of Commaii THE SOUNDING-MACHmE AND ITS USE. 59 rope-sounding, its mechanical success was apparently due in a great degree to the intelligence, patience, and skill of Captain Belknap and the officers who assisted him. A study of Captain Belknap's reports suggested to me the idea of improving the machine in order that it might be worked with fewer demands on the watchfulness and ingenuity of those having it in charge. Captain Belknap having been forced to reel in by hand, it occurred to me that if the wire were connected with an accumulator, interposed between the reel and the sinker, to show the strain upon the wire at all times when reeling in. and to ease the sudden jerks caused by the oscillating motion of the ship, steam might be applied for reeling in, and .thus the labor and difficulty attending this operation by hand might be obviated. My views were communicated to the Superintendent, who at once approved them. Under instructions from him, a machine having an accumulator was designed during the summer of 1874, and. as the drawings advanced, other ideas were incorporated with the original plan. From my drawings, a machine for experimental purposes was made in the winter of 1874-75 (Plate 7). This was used for three years on board the " Blake," and, as we had previously used the original Thomson machine (Plate 6) for six months, opportunity was afforded for comparing the relative merits of the two. Some faults arising from bad mechanical arrangement had first to be corrected in the Sigsbee experimental machine, after which, even under the most unfavorable circumstances of wind, sea, and current, it performed as had been anticipated. This machine being experimental and open to such improvements as experience might suggest, it was always intended, if suc- cessful, to replace it by one embracing these improvements. Accordingly, drawings were prepared during the summer of 1876 to this end (Plates 36, 37, 38), but, for various reasons not necessary to be recited, the machine was not made until just before my detachment from the survey, so that I have never seen it at work (-Plates 8 to 15, inclusive). Since this book was commenced Commander Bartlett, my successor on board the "Blake," has used tlie new machine for six hundred and sixty- four casts, in depths from one hundred to 3,000 fathoms, many times under trying circumstances in trade-wind seas about the Windward Islands of the Caribbean Sea. Commander Bartlett and others onboard the "Blake" 60 DEEP-SEA SOUNDING AND DEEDGING. agree in representing its working as wholly satisfactory. Among the "Blake's" officers who have rendered these favorable opinions are those who have operated the Sigsbee experimental machine also, and one who has worked both the original Thomson machine and the Sigsbee experi- mental machine. It is highly probable that so small a vessel as the ''Blake " must have been very lively in the seas she encountered during her recent cruise ; hence if a governor on the motions of the sounding-reel possesses any advantage, it must then have been needful on board the ''Blake," particularly as most of the work was done with a reduced Navy steel reel weighing, independently of the wire, at least one hundred and twenty-five pounds. Of the governing action of the new or latest form of the Sigsbee machine the opinions cited were most favorable. I will state briefly that the experimental machine was the same in prin- ciple as the new one, shortly to be described, but in the latter spiral springs have been substituted for the helical springs used in the former; there has also been added to the new machine a strain-pulley to prevent the crushing of the reel, and a swivel-pulley to admit of the vessel steaming ahead on her course when reeling in the wire. The idea of using these two pulleys was obtained from Sir William Thomson's machine in its form as improved by him after Captain Belknap's cruise, but Sir William Thomson's mode of construction was departed from in order to suit the different shape of my apparatus. The modification or improvement made by me on the original Thomson sounding-machine lies chiefly in the employment of a peculiar kind of accumulator, and its adaptation to the various uses of accumulator, dynamometer, brake, correct register, and governor. The accumulator eases the jerks that may be brought upon the wire while reeling in, and as a dynamometer it shows the strain upon the wire at each, instant during the same operation. The brake gives a handy means of applying resistance to the reel without weights, and, with its attachment of spring scales, provides a second dynamometer, which, during the operation of paying out, shows the tension upon the wire and the resistance which the reel suffers. The brake, in connection with the accumulator, operates as a governor on the motions of the reel when paying out wire. The odometer, used as a register in a special place, gives, without interpolation, the amount of wire played out. > H W CD THE sou:nding-machine and its use. 61 It may be stated, after four years' experience in deep-sea sounding with wire in a small steamer, that these changes and additions, excepting, perhaps, the use of the odometer as cited, are desirable and of sufficient value in prolonged work to warrant their extra cost. With the experimental machine (Plate 7), eight hundred and twenty-four soundings were taken in weather varying from calms to gales, and with scarcely any annoyance whatever. The latest form of the Sigsbee machine (Plate 8) , being more compact and having less friction in its Avorking parts, has been found to be more convenient. In comparing the original Thomson sounding-machine for wire (Plate 6) with the Sigsbee form of the machine (Plate 8) the following points have been established. I. For reeling in the latter has the advantage at all times. II. For paying out when there is no distinctly perceptible rolling or pitching motion on the vessel, there is no gain worth mentioning-, except- ing at the instant of striking bottom. III. When there is such motion the advantage is largely in favor of the new machine — greater in degree as the motion becomes excessive. IV. In handiness the comparison is always in favor of the latter. Before passing to a detailed description of the new machine it is proper to state that my efforts to improve the sounding-machine have been made in the interest of good work, and that the kind manner in which Sir Will- iam Thomson has been willing to receive co-operation in improving the apparatus has been very encouraging and gratifying, although nothing less could have been expected from that distinguished scientist. I have already stated that, in point of accuracy, the original form of the machine by Sir William Thomson was successful from the first, and it is particularly to be understood that the sufficiency of the original machine in that respect is fully recognized. 62 DEEr-SEA SOUNDING AND DEEDGING. DESCRIPTION OF THE LATEST FORM OF THE SIGSBEE SOUNDING-MACHINE. (Plates 36, 37, 38.) The Reel (A, Figs. I, II, III, IV, aiid V) is, for convenience, one fathom in circumference of drum, less an allowance for the thickness of the wire; that is, the initial turn of wire taken around the bare drum measures exactly one fathom in length. At the side is a score, which is V-shaped in cross-section, for receiving the friction-line. The reel is rigidly attached to its axle by a key, and for each end of the axle a crank should be provided. The drawing was made from the Navy brass reel, the form of which is not now approved. (For another style of reel see Plates 16 and 17.) If the key by which the reel is iittaclied to its axle be made to admit of easy removal, the axle may be withdrawn when the reel is to be stowed in the tank of oil or lime-water. In this way a smaller tank may be used. For a description of the tank ordinarily used see Chapter II. In the machine made for the "Blake" the axle rests on friction-rollers. This is not necessary, but it ^ives a very smooth movement, and, by lessening the ft'iction of the axle, a more accurate indication of the amount of resistance upon the reel, when paying out, is given by the readings of the two scales to be described hereafter. I7.e Register for the Axle of the Reel (B, Fig. 1). ThlS is thC SaUlC iu COU- struction as the register used by Sir William Thomson on the original machine, but it is marked differently. (See drawing, Plate 38, on which, however, the thousands dial has been marked in tens where it should have been marked in unit's.) A worm on the axle of the reel engages the gearing of the register. Since the record of the instrument gives only the revolu- tions of the reel — turns, not fathoms — a correction-curve (Plate 41) or other means of reduction must be employed in order to ascertain the true length of wire payed out at a sounding. For ;i ready method of measure- ment see Odometer in the course of this description. The Reelinuin or strain J^ullev (C, D, E, FlgS. I, IV, V). CompOSCd of three separate pulleys, C, D, and E; the score E, for the wire; the score C, for a rope belt to connect with the friction scoreof the reel, if desired ; and the score D, for a rope belt to connect with a hoisting-engine. The two ])elts are shown " brought to"" on Plate 13. For eacli end of the axle a crank should be provided. The axle is made in two parts, squared and slotted to clutch each other. That part which sustains the pulleys is free only to revolve in its bearings, while the other, besides revolving, slides in its bear- THE SOUNDING-MACHINE AND ITS ITSE. 63 ing ill the line of its axis to admit of unclutching, tliat tlie wire and belts may be ''brought to" on the strain-pnlley. (Fig. V.) The scores V niid 1) sliould be V-sliaped in ei'oss-s ' of a cai.stau or of a wineli-liea.l. I do not full v believe ii aiisxv.MiM.u tlie eoiiditious of weigbt and strengtb. As hu Inindi-eil pounds nmy be fixed upon as tbe weiobt beyond Tills inelndes tbe axle and Kttings and assumes a well-piv eoil of wiiv. Within this limit great strength may be see the latter is m.t yet e^^/reZ// rertain. an.l t,. increase the doubtful expediency, it is, perhai)s, not saf,. to advise th The strain-pulley i.'laeed U]>on the •• Blake's ■' new soundi The score E sho essity for a strain uld be 1 pulley ■ounded li ke the barrel s only ushing force whi, if we 1 ',"i'a rr a be br ■ IJlakc rts of ; ts; but ought ■torily t is not advisabl,. i-olmbly enough f, HE; hide the V I reel, of the s is of ,se of the strain-i bine was added i fsbeennichine tha inlley 1 nore fo .e wholly ■el shown ixiuiid on I'la ished. an for of the tes 16 of the , stitution for the present strain-pulley of a steam-engine, similar to tlnat shown on Plate 18, of which a description will be given in this chapter. If the tly-wheel of this engine were given the three grooves menticnied, either of the above modifications would possess all the advantage of an independent strain-pnlley, ami either might be employed with equal facility for the same purpose. Tlie Aecumuiatoi: — CoHiposed of the tubes F, F, F, &c. (Figs. I, II, III, IV, V), containing the spiral extension-springs G, G (Fig. Ill) which con- nect with the movable cross-head H (Figs. II, VII, VIII, IX) by means of the chain, or wire rope, I, I (Figs. I, II, III) passing over the pulleys J, J (Figs. I, II, XII). The tubes are hinged at K, K (Figs. I, II, III, IV) that the upper sections may be lowered for convenient stowage ; they may be graduated for the number of pounds pull on the wire, either the upper or the lower arm of the cross-head being made the index. There are three sections to each -tube, the lower section of each, beneath the bed-board, unscrewing for stowage or transportation (Plate 12). The cross-head H, containing the pulley L (Figs. I, VII, VIII, IX), moves on the steel guides M, M (Figs. II, III, V, XI), which are fastened by screws to the tubes. The pulley L is rigidly attached to its axle by a key. To the axle is attached an odometer, N (Fig, II, Plate 37, and drawing on Plate 38). This pulley is exactly one yard (one-half fathom) in circum- ference on its drum, less the allowance for thickness of wire. One-half the number of revolutions of the pulley, as shown by the odometer, will, therefore, give at once the number of fathoms of wire payed out or reeled 64 DEEP-SEA SOUNDING AND DEEDGING. in. The action by which the accumulator operates as a governor will be explained when the method of taking a sounding is described. The extension-springs used in tlie accunnilator are eacli twenty-eight and a half inclies long and 1\vo and an eighth inches outside diameter; they are made of No. 4 (American gauge) steel wire; each weighs eight and a quarter pounds, and has a movement of four feet (approximately) for a strain of one hundred and fifty pounds directly applied. When the purchase is considered, it is seen that a pull of one hundred and fifty pounds on the wire will move the cross-head four feet, which will correspond to a rendering or cushioning of the wire a dis- tance of eight feet. Thinking that these springs might he found too stiff, a couple of spare sets were provided the "Blake," which were made from smaller wire hut on the same mandril used in the manufacture of the first set. A single spring from one of the spare sets gave a movement of four feet for one hundred pounds strahi, and from the other spare r°t an equal movement for eighty pounds strain. The original pair seem to have done well, however. The springs were made by John Chatillon & Son, 91 Cliif street. New Yoik, at a cost of about $12 The upper section of each tube is of two and a half inches inside diameter and an eighth of an inch thick- ness of metal. The two lower sections are the same as the others in inside diameter but are a quarter of an inch thick. Within the limit of its elasticity the movement of a spring varies as the strain; hence the tubes of the sounding-machine may be graduated for the number of pounds of strain upon the wii-e as follows : Reeve the end of the wire from the reel over the cross-head pulley and pawl the reel. Hang a weight of twenty. five pounds from the end of wire, the and mark the point on one of the tubes opposite which the upper arm of the cross-head comes to rest, which point we will call A. Increase the weight to one hundred poiuuls and mark the corresponding point on the tube indicated by the upper arm of the cross-head, which second point we will call B. Lay off on a thin strip of wood or metal the distance A B, and divide this distance into seventy-five equal parts. Each division will correspond to a strain of one pound on the wire. Continue the same scale above the point A and below the point B. Lash the strip of wood to the tube so that the point A on the former will coincide with the point A on the latter. The upper arm of the cross-head will be the index. Sliould the rope by which the cross-head is suspended stretch or shrink thereafter, add twenty-five pounds to the wii'e as before, and determine the position to which the point A of the tube has shifted. Having deter- mined the new point A on the tube, bring the point A on the strip of wood to a coincidence therewith, and the graduation will have been corrected. It is obvious that to get a sensitive accumulator dynaniometer, or governor, it is necessary to keep the weight of the cross-head and its pulley as light as strength will permit. There will be very little lateral strain upon the cross-head other than that due to its own weight when the vessel is heeled. The cross-head pulley should be so made as to permit its removal from the cross-head without unshipping the latter from the guides. Figs. VII and IX show an arrangement to prevent the wire from flying off the pulley, in which the small spiral springs should be very supple. O, O (Figs. II, VII, VIII) are shoulders, to guard against the bending of the cross-head in the event of parting the chains or ropes I, I, or of parting the wire. Should the chains part the cross-head would fall, the lower shoulders striking on the studs P, P (Figs. II, III, V, and also Plates 8 to 11 inclusive). Should the wire part while reeling in, the cross-head on flying up would receive the blow against the upper shoulders, the latter strikhig against the cross-piece upon which rest the pulleys J, J. On the " Blake's " machine a piece of rubber is fastened under the cross-piece to ease the shock. On the latest machine — on board the " Blake" — the studs P, P constitute buffers. A hole is bored in the upper end of each stud in the line of the axis of the stud, into wliirh a spiral compression-spring is placed. A simple piston cut from a cylindrical steel or ii-on rod. (if a size tn lit loose in the hole, is allowed to rest on the spring and project above the stud. Per- haps the i)laiii stud ra|i|i<'d with rubber or padded canvas would do as well. The Swivel Ptiuey. — The object of this pulley, S (Figs. I, II, V), is to alloAv the wire to be reeled in while the vessel is steaming ahead. A sleeve > W CO ^^•- THE SOUNDING-MACHINE AND ITS USE. 65 of steel, or case-hardened iron pipe, is fastened to a casting that is bolted to the bed-board. This sleeve, which is a fairleader for the wire, has, slid- ing freely around it, a brass or iron collar to which is bolted the arm holding the pulley. In the positions shown in Figs. 1 and V the pulley is ready for reeling in, and it may be swung latterly to any desired angle (see also Plates 11 and 13). The score will always be in the same line with the score of the cross-head pulley. Before paying out the wire — or before reeling it in if it be not intended to steam ahead during the opera- tion — the arm T, which holds the swivel pulley, is released from the bolt U, when the arm will pivot on the bolt V. The pulley should then be lifted clear of the wire, turned to one side, and secured (see also Plates 9 and 10). The SMiing-scaieg (W aud X, Figs. I aud IV). — In paying out the wire, the difference between the readings of the scales W and X gives the num- ber of pounds of resistance imposed upon the reel by the friction-rope at the instant of taking the readings. Tlif scales slinulil lie of tlie kind tliat hav,- a long nioveuu'iit of the index, or iioiuter, for a small exten- sion ,.f the rontaiiied spring, and they should he strong .Miough t THE SOUNDINCt-MAOHINE AND ITS riSE- B9 the machine is set up the strain upon tlie wire is thereupon lessened, and the consequent effort of the cross-head to rise — imparted by the reaction of the springs — is transferred to the friction-Une. Tiius a greater resistance is automatically placed upon the reel, checking its speed or stopping it altogether — rarely the latter — until the rising of the vessel or the slowing- down of the reel causes an increase of strain upon the wire. As the strain increases the cross-head is borne down, which eases the pull on the fric- tion-line, allowing the reel to revolve more rapidly; and so on with recip- rocal effect. When the vessel is quiet the accumulator has no inherent capability of varying the amount, of resistance upon the reel. This alter- nating movement of the cross-head when paying out is, of course, scarcely perceptible to the eye. Although the effect of the governing action on the motion of the reel is distinctly seen, the motion is not fitful, but remark- ably smooth. No instance is recalled of the wire jumping from the drum of the reel when using the governor. Commander Bartlett, during his six hundred and sixty-four casts with wire, met with no such accident. From what has been said it follows that the operation of paying out is progressing safely if several ])ounds of surplus j^esistance is ujoon the reel, according to the rule, and the wire is keeping constantly under tension. It appears by the records of work done in the Navy that the recom- mendation of Sir William Thomson to use a weight at the end of the wire has been held in practice, as much as four pounds sometimes being used. If such a weight, or any other considerable weights — as water cups, &c, — be used on the stray-line or wire they should be taken into account in applying the resistance. The sinkers and sounding-rod being the only weights which are to be permitted to reach the bottom, all other sub- merged weights should be counterbalanced at the reel. With the original sounding-machine for wire, when bottom is reached the weight of the sinker and sounding-rod ceases to act as a moving force for the reel ; hence, if a resistance slightly in excess of the weight of the submerged wire and its attachments — above the rod and sinker — has been placed upon the reel the latter will stop. In the same case, with the Sigsbee form of the machine, the weight of the sinker and sounding-rod not only ceases to act as a moving force for the reel, but the force due to the weight 70 BEEP SEA-SOUNDING AND DEEDGIKG. of the sinker and rod is automatically transferred to the friction-line, because the cross-head, being freed from the bearing-down effort of the weight of the sinker and rod, rises and communicates that effort to the friction-line. This peculiarity may not appear to give any great advantage over the original machine, yet it is a safeguard, and provides a reaction against the momentum of the reel at a critical point. Since it results, without extra cost, from the action of such parts of the machinery as are devised for other, and perhaps more necessary, purposes, it may at least be considered an acceptable feature in the working of the apparatus. In practice it is found, both with the original Thomson and the Sigs- bee machines, that to maintain a rapid rate of paying out the pull upon the friction-line (not friction, but pull upon the line) has gradually to be reduced froim the time of starting the sounding. This is chiefly due to the friction on the submerged wire. On board the "Blake" we would occa- sionally, in very deep water, find the cross-head nearly at the top of its guides, and the reel controlled by the resistance due to a very light strain on the friction-line. In this case we would lose to a considerable extent the governing action of the accumulator and the automatically increased resistance at the instant of striking bottom. The -remedy was to use a friction-line of smaller stuff when sounding in very deep water, or to decrease the length of the arc of bearing-surface which the friction-line had in its score by making its standing part fast somewhere above the bed-board of the machine. The use of a heavier sinker will also serve the same purpose. In regard to the size of the friction-line only that part which is wrapped in the friction-score is of much moment. In a heavy sea, if sounding from the bow, the violence of the vessel's motion may cause the reel to "race'' occasionally, notwithstanding the governor. This will be understood when it is stated that the "Blake" has been known to plunge so quickly as to slack the wire when reeling in by steam. To provide against racing in seas exceptionally heavy for the work, we used a very simple and completely successful device. While the reel was unwinding the wire under the usual frictional control a small toggle turned into the friction-line outside of the pulley Y (Figs. I, III, V), on the same side of the bed as the friction-score of the reel, was made to THE SOUNDING-MACHINE AND ITS USE. 71 bind with a force of several pounds against tlie pulley, by setting up taut on the standing part of the friction-line at the scales X (Fig. I). Thus, while the governor was free to automatically increase the friction upon the reel as occasion demanded, it was incapable of decreasing it to an amount less than that due to the resistance of the toggle against the pulley. Stretching of the friction-line will cause the toggle to recede from the pulley, and the friction-line may have to be set up afresh at the sfanding part several times during a deep cast in very heavy seas; this, however, does not necessitate a stoppage of the reel. A close inspection will show the toggle on Plate 9. While this device may be dispensed with, even in very heavy seas, by the exercise of a little care, its use under such circum- stances permits- a more rapid rate of descent. When paying out wire, oil or fresh water should be applied freely to that part of the friction-line resting in the friction-score. This will give smooth work. Water, if used, must be applied frequently; oil not neces- sarily so often. As soon as the sinker strikes bottom, which is made apparent l^y the stoppage of the reel, read the register or the odometer, and, at the same time, ship the cranks ©n the axles of the reel. Throw the bight of the fric- tion-line out of its score, and, to insure the detaching of the sinker, pay out cautiously one or two turns of the wire, if necessary, until the strain upon it is eased. Then reel in a few turns slowly and carefully, when the distance which the cross-head is borne down along its guides will indicate if the sinker be clear. Usually, with a good form of detacher, it drops off at once on striking bottom, requiring no actual slacking of the stray-line or wire. The exceptions are most likely to occur when paying out slowly in strong currents. In paying out extra turns of wire to detach the sinker it should be remembered that the wire must not be allowed to coil on bot- tom; nor should the stray-line be allowed to foul the rod or sinker on the bottom. If a thermometer have been fastened to the stray-line for observ- ing the bottom-water temperature, care should be exercised that the sound- ing-rod may not drag along the bottom while waiting for the thermometer to register. Although we always used steam for reeling in, it was our invariable custom first to reel in fifteen or twenty turns by hand before connecting with the engine, and with inexperienced supervision at the 72 DEEP-SEA soundi:ng and deedging- machine the last fifteen or twenty turns should also be got in by hand — that is, by men working at the cranks. If the strain-pulley is to be employed for reeling in, Plate 36 (dotted line, Fig. 1) and Plate 11 will show the manner of leading the wire, which is as follows : The last or uppermost turn of the wire upon the reel leads from the latter six or seven times around the wide score of the strain-pulley, "with the hands of a clock" or "with the sun," and thence underneath the reel, over the cross-head pulley and into the water. The power for reeling in is applied to the strain-pulley, from which the wire is passed to the reel with the tension reduced. To keep the parts of the wire from riding over each other on the strain-pulley a standard with a roller is interposed, as shown on Plates 11 and 36. It is seen that the wire, after coming in over the cross-head pulley, passes over a large part of the circumference of the coil contained on the drum of the reel. It is thought that this may pos- sibly cause the wire to act as a belt to revolve the reel for taking the turns from the strain-pulley, but if the arrangement prove insufficient for the purpose stated, a loose belt of rope, just long enough to fit, should con- nect the friction-score of the reel with the score C (Fig. V, Plate 38) of the strain-pulley. The weight alone of a small rope would, doubtless, give enough friction for a connecting slip-belt. The use of the score D (Fig. V, Plate 38) is to connect the strain- pulley with a reeling-engine by a rope belt. Plate 13 shows the two connecting belts that have been described. When the strain-pulley is not to be used a rope belt maybe taken directly from the friction-score of the reel to the V-groove of the reeling-engine. KEEPING A TIME-RECORD OF SOUNDINGS. It was our custom to keep a record, as shown on Form 1, next page, at every sounding taken with wire. This practice is useful in various ways. The officer of the deck is thus kept constantly posted as to the speed of the machine, and is given experience with regard to its capabili- ties; should the register cease to record from any cause the fact is made known, and when plotting, if a non-agreement is observed between sound- ings on the same or intersecting lines, the means of verifying tlic figures relating to the soundings are at hand. ji -^:::^ > THE SOl7NDIN(;-MA CHINE AND ITS USE. FOEM 1. U. S. COAST SURVEY STEAMER "BLAKE." Locality, 20 miles N. W o/So,, brerold. Dat », Apn 23,1879. Sounding No. 25. Line, P. P. Turns Keel REELING OUT. REELING IN. Times. Intervals. Times j Intervals. REMARKS. To bt- i.iadf by tl.e Officer of tlie Deck. Kegis- TEB. H. M. " Jll •■ ! s. II . s. 11 1 21 1 12 30 1 20 :| "55" Sinker used, Slml. Weight, 60 lbs. 100 i' i 22 34 i! 1 02 29 25 47 Was sinker detached or recovered ? Dehwlml m \: i 23 25 i 51 28 38 47 No. of fathoms of stray-line used, 9. 300 y I 24 j 15 '.\ . 50 27 51 : 49 No. of turns of wire in use on reel, Ufl58. UOO \ 25 1 06 1 51 : [27 02 54 Kind of reel used. Navy steel reel (reduced). .500 25 ; 58 ' 52 ; | 26 08 54 ■Weight of reel used, mi lbs. 600 26 52 '54 \\ 25 14 59 Reeled in by Steam (hand or steam?). 700 27 : 46 54 \'. 24 15 1 01 Reeled in iirst l.i turns by hand. 800 28 : 43 57 ' 23 14 1 04 Reeled in last V, turns by hand. • .900 29 43 1 00 : 22 10 1 03 Wind N. E. to N. N. E. Force 1 to .}. 1000 30 41 , 58 : ■ t 21 07 1 07 State of the sea. Light swell from E. N. E. 1100 31 4:3 1 ; 02 , 20 00 1 10 Vessel rolling. Easili/. 1200 ! 32 i 46 : 1 i 03 i; 18 50 1 10 Vessel i.it.-hiny-. Easily. 1300 33 48 1 02 f ' 17 40 1 13 Modified Belkmq} rod loith Sigshee detacher used. WO 34 : 54 1 1 06 j 16 27 1 18 Reeled in sloidy because the aire had seen much prerwu mo 36 ; 01 ;^ 1 1 07 1 . 15 09 1 1 18 service. 1600 : 37 09 : 1 08 |i 13 51 ,| I 21 Thermometer and water-cup on the dray-line. i700 i 38 15 ; 1 06 jj 12 30 i 1 23 LOSSES OR CASUALTIES. 1800 ji 39 1 26 '; 1 11 !; : 11 07 i 1 24 Nmie. 1900 \\ 40 35 :[ 1 09 ; ; 09 43 1 25 WOO ! 41 [ 48 i 1 13 ji 08 18 J 1 25 SlOO ! 2200 i 43 02 ; 1 44 11 ; 1 14 j ' 06 09 ij 05 53 ; 1 16 :| 1 37 34 mo 45 24 ; 1 13 I : 03 42 ' 1 38 Reading of Register 2, 76-5 turns. mo ■ 46 \ 38 ! 1 14 ' 02 04 ; 1 31 Correction for stray-line 6 2500 47 53 'j 1 15 1 12 ' 00 33 [j 1 66 Correction for turns of wire. 158 2600 1 49 i 08 1 15 58 37 1 53 S700 2765 11 50 ! 24 J 1 51 17 i 16 53 11 56 55 44 45 59 Correct Oeptn 9,929 futhoms 2900 SOOO - .j Totals. ! ^ 29 45 34 35 Signature of Officer of the Deck :_ Signature of the Recorder: The al)( the deepe V Commander Bartlett to show tlie t for which it had heeii used up tf) that time. The figui ich is verj' slow for the "Blake, is shown to have been l-" 01^. and for reeling in 1"' 11-. revolving at the rate of one hundred turn,? (about one bund in from these two soundings it appears that the vessel ^v: the wire had something to do with it, or, since these were was decided to be cautious. The "Blake" being an econo ing day and night with different officers in charge of tlie n make quick time is rarely attempted. 10 D S rorking of the Sigshee machine in •epresent fair work, excepting the of paying out, per one hundred fathoi The sinker touched bottom when the reel was ed and twelve fathoms) in 1"> 16^ While reeling s not steamed ahead. Probably the weakness of ;he deepest casts ever made fi-om the "Blake," it ii<'al vessel in the expenditure of coal, and work- achine, to take much risk with the wire in order to 74 DEEP-SEA SOUNDING AND DREDGING. 00 1 i 1 1 •ui Sui -paj sraoiiiiji ooi 5;S5Sg52gS5S??5;5!3Sg§SgS5; i a 1 5 ;::;;::;; i-^ i :::: i-^ ;;: : •m Sui ^ §S5S3§gSgSSS^^g3!5:3gSSS§ g »SS3Sa333SS""*°'°'SSSS'"°' ^1 E -^^d suioiiiBj OOI jad anip aS^aax^y gSSS§SggSS§SSS!3gS§SSSS S : ; : i-^ ; ; : : i-^ : : ; : : i-^ : : : ; !§l ■jno 3m -A'ud auii} apq^^ SSSSSSSSSSSS^SSSSSSSSS y^ 1 li ^ ssasgsa?;3ss°'«*»ssssssn •s. > 1 ^ 1 ^ ^ > ^ 1 '^ 1 5 '1 '1 1 i ^ 1 i 1 > '5 1 °- 1 > '"= > 1 1 1 •<: i 1 > ■1 1 1 1 1 > a i-t > i 1 1 1 "C ■c ■t 5 5 s 5 5 ^ i 1 3 j I 1 5 t 1 1 1 ^ .£ 1 ^ ^ 1 't jj I. •smoqiBj m q^da a 1 1 o 3 i ! 1 ,- I S 1 2 1 i ^ s c 1 1 HI i ! 8 II 1 1 I I 1 1 1 " a ^ f M ?§ i i liiSlI ll^llfi ■V a ^ S ^ I llll I , f-f f f f r It ■ li ^^^^H^ ^^ Id > THE SOUNDING-MACHINE AND ITS USE. 15 HAULING BACK A LEAD SINKER. After getting an accumulator the greater number of our casts no deeper than eight hundred or 1,000 fathoms were taken with the thirty-four-pound sinker, which we always hauled back by steam. The accumulator, acting as a dynamometer, will direct the judgment in regard to the safety of haul- ing back, but in respect to the advisability of the measure, economy of time and money will have much influence. We thought the small saving of shot-sinkers no object in depths greater than 1,000 or 1,200 fathoms, for the rate of paying out with a light lead then became so slow that the loss of time in favorable working weather was the more important consideration. In regard to the safety of hauling back the lead, the state of the sea made but little difference with us in a depth of 1,000 fathoms. Sometimes the accumulator cross-head would traverse its full range while we were hauling back in a heavy sea. The following shows work with the lead: . U. S. COAST SURVEY STEAMER '-BLAKE." Locality, Off Grenada. Date, March S, 1879. Sounding No. 37. Line K. Turns KEELING OUT. KEELING IN. Keel Times. Intervals. Times Intervals. To be made by the Officer of the Deck. TEH. M. s. =■ M. s. M. - 4 20 4a 4 43 30 1 00 Sinker used. Lead. Weight, 34 lbs. 100 21 42 57 42 30 46 Was sinker detached or recovered ? Recovered. 200 SOO 22 23 35 1 53 00 41 41 44 01 43 49 No. of fathoms of stray-line used, 9. No. of turns of wire in use on reel, 4,387. UOO 24 30 55 40 12 50 Kind of reel used, Navy steel (reduced). 500 WO 25 26 32 40 02 08 39 22 18 1 1 04 03 Weight of reel used, 125 lbs. Keeled in by Steam (hand or steam V). 700 27 50 10 37 15 1 : 13 Reeled in first 8 turns by hand. 800 29 25 35 36 02 1 1 03 Reeled in last 15 turns by hand. 875 4 30 35 1 ^ 10 4 34 59 1 Wind,Eaa<. Force, 2. r 1 9 50 1 * 31 State of the sea. Moderate. Vessel rolling, 1 ^^ Vessel pitching, j 875 turns. 6 Correction for stray-li f wire LOSSES OK CASUALTIES. The times are fair, but would be slow for work with a shot-sinker. With the vessel quiet, aud particu- larly when sounding Avith shot, considerable time is sometimes gained in deep soundings by allowing the reel to pay off the wire very rapidly, under less resistance than is called for by the rule, until the sinker has arrived within several hundred fathoms of the bottom, when the resistance is increased to the safety point. To attempt this, one must feel sure that he can foretell the depth approximately. 76 DEEP-SEA SOUNDIi^G AND DEEDGING. ^ i s a s y g <. .£ III! ^00 S •«!§"! ..• 5:§5:g^Sg5S55g^SS§ .lad fluiij ag«,wAv s j^iiiiM:;:;:''^"' .,„g„, X SS^SSS^SSSSggSSB -laaj 9unj f.[oqAv ^ *io*u5t-«^tt.». "i 1- 1 J 1 ^^ C) 8.3 41 45 49 " 42. 8 During the operation the vessel was steam- n 5.3 30 34 37 1 07.0 ing in the trough of a moderately heavy 100 7.3 41 45 49 48.7 sea, and was rolling and pitching consid- 100 6.3 39 41 43 56.4 erably, sometimes even heavily. In the 250 7.0 45 50 54 50.8 first column 8 fathoms of stray-line are 250 4.0 35 42 47 1 28.8 included in the given length of wire out, 500 6.5 52 60 65 54.7 and the strain in every case is that due to 500 3.6 37 43 44 1 38.7 the pull of wire, lead, and 8 fathoms of 750 7.0 67 69 72 50.8 stray-line. The lead used was 18 inches 750 3.6 43 45 46 1 38.7 long, of the ordinary commercial pattern. 1,000 7.0 75 78 81 50.8 PitcMngheavUy. fitted with a Stellwagen specimen-cup. 1,000 5.5 68 70 73 1 04.6 the whole weighing 34 pounds. 1,250 7.0 91 93 96 50.8 Repeated. Having paid out 2,000 fathoms, we com- 1,250 4.7 70 72 74 1 15.6 menced to reel in hy steam, the vessel's 1,500 6.7 100 102 103 53.0 speed heing 6.6 knots. 100 fathoms came 1,500 4.5 74 76 77 1 19.0 upon the reel in 3'" lO'* ; but on attempt- 1,750 6.5 105 108 110 54.7 ing to reel in the second 100 fathoms at 1,750 3.6 75 77 78 1 38.7 the rate of about 3™, the vessel going 2,000 7.3 125 126 128 48.7 at the same speed as before, the wire 2,000 3.7 75 78 79 1 36.0 parted— a fair break, and not in a splice. It is seen that when the wire parted it was being hauled through the water, with the lead and stray-line attached, at a speed of 8.57 knots per. hour or one hundred and forty-four and three-fourths fathoms per minute, which is at the rate of one hundred fathoms in 41.4 seconds. When there were 2,000 fathoms out, and the vessel was making a speed of 7.3 knots, the wire, line, and lead were being towed at the rate of one hundred fath- oms in 48.7 seconds, yet the maximum strain upon the wire was only one hundred and twenty-eight pounds, of which about forty-five pounds were due to the stray-line and sinker. 1 THE SOUNDING-MACHINE AND ITS USE. 83 Although the table shows that an accumulator, as such, is not required when reeling in while steaming ahead, yet as a dynamometer it would perform important service. The dynamometer, by showing the strain upon the wire at each instant, would permit a safe and rapid rate of reeling in without a resort to time-interval checks involving a considerable calcula- tion, or to the use of prepared tables; and should sea-weed or other mat- ter held in suspension below the surface of the water foul with the lead or sounding-rod the fact would be made known at once by the dynamometer. In the performance of the operation under discussion the main object would be to get the vessel as far ahead on her course as possible; while the time consumed in reeling in would be of secondary importance, and need be limited only by the time required to reach the next sounding station. If in the time that otherwise would be occupied by a vessel in reeling in with the wire vertical, she can succeed in steaming ahead on her course, however slowly, and at the expiration of that interval of time can start ahead at full speed with safety to the wire which is towing astern, she will obviously have gained by the method of steaming ahead while towing the wire. This suggests the following as being probably a good plan for general work in this particular. Decide on the working strain to which it will be safe to submit the • wire that is in use. After bottom has been reached send the vessel ahead at a speed which will admit of a slow rate of reeling in without exceed- ing the accepted working strain. Constantly keep this strain upon the wire — first, by gradually increasing the speed of the vessel while main- taining the initial rate of reeling in, and then, after the vessel has reached full speed, by gradually increasing the rate of reeling in. I have known several cases in which sharks have parted the wire by seizing the bright instruments attached to the stray-line. Certainly below five hundred fathoms, and probably below one hundred, this remote dan- ger will cease. When the wire is towing, the chances of being thus an- noyed are greater than when reeled in vertically, and it is suggested that the outside of the instruments might be painted a dead black or a dark lead-color to make them less alluring to sharks. 84 DEEP-SEA SOUNDING AND DEEDGING. DESCRIPTION OF A NEW STEEL REEL: REMARKS ON CRUSHING FORCE. (Plate 16.) A cast-steer drum, with the two outer flanges A, A, and the three inner flanges B, B, B, the thickness of metal being one-eighth of an inch throughout, excepting at the angles G, C, where it is somewhat thicker. The one-eighth-inch sheet-steel side-plates D, D, set up to the drum by the half-inch steel socket-bolts E, E, E, &c., which pass through the inside flanges B, B, B, and are secured with the nuts F, F, &c. The drum should have as nearly as possible a perfect contact with the side plates. The cast-steel friction-ring, with score G, secured to the steel bolts E, E, E, &c., by the iron screws H, H, H, &c. The wrought-iron three-eighths-inch riveted socket-bolts I, I, I, &c. The cast-iron center-block J, to which the steel side-plates are secured by the three-eighths-inch wrought-iron riveted bolts K, K, K, &c. The steel axle L, to be fitted with cast-iron or steel ratchet-wheel and a steel worm, as shown on Plates 36, 37, 38. The wrought-iron or steel key M. The steel w^ashers N, N, N, &c., to give additional strength to the out- side flanges of the drum at the points C, C. No brass is to be employed in the manufacture. This reel weighs about eighty-one pounds without the axle ratchet- wheel and worm, and about ninety-five pounds when fully equipped. The drum should exactly accommodate one fathom of the sounding- wire at a single turn. The diameter of a circle having a circumference of one fathom is 22.918 inches, and this being decreased by 0,028 inch, thickness of the wire, gives as the diameter of the drum 22.89 inches. All the joints sJwuldhave, as nearly as possible, a perfect ^t, that the reel may he very strong as a whole. A reel made after the drawings shown on Plate 16 was put on board the "Blake" when the vessel had come under the command of Commander Bartlett. The view of this reel from which Plate 17 was made was ob- tained during a rain and the plate is therefore not very successful. Under the direction of Commander Bartlett, Lieutenant Wallis sub- U. S. COAST SURVEY. DEEP SEA SOUNDING AND DREDGING. Ftq. 1 1 , 1 ,1 , 1 , 1, I .I , I , I , I , l„iJ Scale of Inches Ft^.2 NEW STKEL REEL POR SOU-NDTNG AVITH WIRE. DEVISED BY LIEUT COMDB. CTl.SIGSBEE, U. S.N..ASSIST COAST SURVEY THE SOUNDING-MACHINE AND ITS USE. 85 jected the new steel reel to the following experimental test: 3,868 turns (4,025 fathoms) of sounding-wire was wrapped upon it under an invariable tension of fifty pounds. If every part of the reel and the enwrapped wire remained rigid throughout, then the reel must have sustained a crushing force of 172if|^ tons; (^ 2940 )• Granges were carefully applied to various parts of the reel during the experiment and on its completion. After the whole 4,025 fathoms had been reeled up, the outer flanges A, A of the drum were found by the gauge to have retained the same distance from each other which they had at first, and no part of the reel had suffered any change that could be detected, excepting at the seam, on either side, where the side-plates are set up against the under side of the drum ; here the outside face of the flange and the outside face of the side-plate — the vertical faces — were just visibly separated, whereas at first they had been in the same plane. The bearing contact of the joint, however, was perfect, and the side-plates simply gave the appearance of having been forced outward very slightly and evenly all around the seam. Care was taken to detect any excentricity, but the circularity, and the concentric relation, of the parts remained, apparently, perfect. The ultimate strength of the reel had not been reached. Should greater strength be required, the mid- dle inner flange might be made deeper. It is remarkable that the galvanized sheet-iron reel and the Navy brass reel should have resisted, even to the extent realized, the accumulated force which apparently has been brought upon them when reeling back from deep- sea casts. The explanation must, I think, be sought, first, in the elasticity of the reel and its coil of wire under severe compression; and, secondly, in the expansion upon the reel,* in most cases, of a great deal of the wire that had been submerged — an action due to its change from a lower to a higher temperature soon after leaving the water. While it is evident that the turns of wire, under certain relative thermal conditions of the air and water, may contract upon the reel on leaving the water, it is nevertheless true that in nearly all of the casts yet taken by the Navy and by the Coast Survey the reverse must have been the case. In a paper lately brought to my notice it is assumed that the wire, 86 DEEP-SEA SOUNDING AND DEEDGING. in a special case mentioned — depth 1,900 fathoms — must have contracted soon after leaving the water, causing a great accumulated force upon a reel which was crushed, the reason assigned for the assumption being that the air was of several degrees lower temperature than the water. Only the temperature of the surface-water was considered in connection with the air temperature — air, 60°, surface-water, 63°, Fahrenheit. From records of serial temperature work previously done near the locality cited, I get the following relation of temperatures : Fahrenheit scale — air, 60°; water — surface, 59°; twenty fathoms, 57°; one hundred fathoms, 46°; one hundred and fifty fathoms, 44°; bottom, 1,900 fathoms, 35°. A few degrees of daily change in the temperature of the air or the surface-water will effect but little change in the water temperatures below ten or twenty fathoms. From the figures given it is at once seen that in the case discussed by the paper in question the wire must have expanded on the reel. Every part of the submerged wire, excepting the upper one hundred fathoms, must have left the depth of one hundred fathoms, in the ascent, at a temperature certainly no higher than 46°, and in less than one minute and thirty sec- onds thereafter, as shown by the records, it was resting upon the reel. REELING-ENGINE AND ACCESSORIES FOR SOUNDING PURPOSES. During my first two years on board the "Blake" we reeled in the wire by means of a long rope belt taken over the friction-score of the reel and led through blocks to a large hoisting-engine fastened to the deck abaft Ihe pilot-house, in the same place afterwards occupied by the engine shown on Plates 30, 31, 33, and others. Plate 29 (Figs. 1 and 2) will give a good idea of the length of belting required, G being the sounding-machine and A the hoisting-engine. Afterwards a Snyder horizontal engine was placed upon the bed-board of the experimental machine, as shown on Plate 7; it is also located on Plate 29 (Figs. 1 and 2), G and H indicating the sound- ing-machine and reeling-engine, respectively. With this we have reeled in as fast as one hundred turns — more than one hundred fathoms — in twenty - six seconds, and a speed of one hundred turns in forty-five seconds was a very common occurrence. The connection between the reel and the small > m W THE SOUNDENG-MACHINE AND ITS USE. 87 engine was made by a rope belt, for the reception of which the engine was provided with a V-groove fly-wheel. For tightening the belt I designed a pair of tightening-pulleys, which are shown imperfectly on Plates 7, 13, and 14. This arrangement may be described as follows: A standard, to the lower part of which a stud-bolt is fastened to form a pin or axle on which the lower pulley may revolve freely. The upper part of the standard is squared, and sliding freely upon it is a collar, to which a second stud-bolt is fastened to form a pin or axle on which the upper pulley may revolve freely. The upper part of the sliding collar is shaped so as to be capable of holding annular lead weights. The lower part of the endless belt is led over the top of the lower or stationary pulley, and the upper part under the upper or sliding pulley. Any desired degree of tightening may be given the belt by adding weights to the sliding collar.* When the latest form of the Sigsbee sounding-machine was put on board the "Blake" it was not convenient to place the little reeling-engine upon the bed-board while the strain-pulley was retained. Accordingly, the engine was placed as shown at H, Fig. 3, Plate 29 — G being the new sounding-machine. (See also Plates 13, 14.) Plate 18 shows a small incline reeling-engine, designed at my request by Mr. Earle G. Bacon, of Messrs. Gopeland & Bacon, New York, and intended to occupy the place upon the bed-board of the sounding-machine at present assigned to the strain-pulley. The cylinder is of Mr. Bacon's patent trunk pattern, of five and a half inches bore. The standards are joined at the bottom, being cast in one piece, and are cored out in order to make them as light as strength will permit. The V-groove pulley, as shown, might be dispensed with, and the fly-wheel given three scores, cor- responding to those on the strain-pulley .f On board a vessel permanently engaged in deep-sea sounding such an engine would doubtless be connected with the boilers by piping; but for use on board vessels not likely to retain the sounding-machine as a fixture, rubber steam-hose might be used for the steam and exhaust pipes. In 1879 Mr. Bacon offered the following * The tighteniiig-pulley designed for the new machines, now being made for the Navy and for the Coast and Geodetic Survey, is an improvement on the form described. April, 1880. t At my request Mr. Bacon has changed the design somewhat, placing the cylinder between the standards, with its axis vertical. The size of the bed- plate is eighteen inches by ten and a half inches. April, 1880. 88 DEEP-SEA SOUNDmG AND DEEDGING. prices : For the engine complete, without connecting hose or piping, $225 ; for rubber steam-hose, three-quarter-inch inside diameter, five-ply, and served with marline, fifty cents per foot ; for rubber exhaust-hose, one inch inside diameter, three-ply, and served with marline, fifty cents per foot; couphngs, $5 per set. The " Blake's" reeling-engine was worked with a pressure of steam ranging from sixty to seventy-five pounds, for whi.ch the above-mentioned hose is adapted. The New York Rubber Belting Company advertise various grades of rubber steam-hose. r>EEP-SEA SOUNDING AND DREDGING U. S. COAST SURVEY PLAN OF PATENT TRUNK KEELING ENGINE FOTl THE SIGSB£E SOUNDING MACHINE -TO OCCUPY" THE PLACE ON THE BED BOAUD AT PRESENT AS- SIGNED TO THE STRAIN PULLEY. SHOULD THE LATTER NOT BE REQUIRED -DESIGNED BY MR.EARLE C.BACON OF MESSRS. C OPELAND AND BACON, N.Y Scale of Indies CHAPTEK lY. WATER SPECIMENS, DENSITIES, TEMPERATURES, AND CURRENTS; APPARATUS AND METHODS. DISPOSITION OF WATER AND SOIL SPECIMENS. The specimens of bottom soil or material obtained by the "Blake," during her sounding operations, were preserved in glass bottles which were simple cylindrical tubes closed at one end' in the manufacture, about two and a half inches long and three-fourths of an inch in diameter, resembling a small plain beaker-glass, or the cylindrical part of a test-tube. Bottles of this kind are a commercial article, and may be obtained, I presume, in any large city. The wide, unobstructed mouth, which is a convenience both for inserting and extracting the specimen, should be closed with a flat selected cork. The glass bottle for the preservation of water specimens was of a commercial pattern, having a very small neck and mouth, to close which we used a long smooth cork. Its capacity was eight ounces. As an additional precaution, the corks of all bottles containing speci- mens were well waxed. In this state, and labeled with the forms shown on the next page, the specimens were sent to the office at Washington on the completion of each season's work. No attempt to analyze water specimens was ever made on board the "Blake." Shortly before Professor Agassiz joined us for the dredging operations he had procured apparatus with a view of doing something in the way of gas analysis, but he afterwards decided that the proper facilities were not to be had on board the vessel. He suggested, as a plan for the future, that a properly furnished station be established on shore, convenient to some deep-sea basin, whence water specimens might be delivered to the 12 D S 89 90 DEEP-SEA SOUNDING AND DEEDGING. station by the quick runs of a steamer detailed for the purpose. With a station at Tortugas, for instance, the "Blake" could deliver a specimen from 2,(X)0 fathoms within twelve hours after its reception on board. U. S. COAST AND GEODETIC SURVEY, Carlile p. Pattersox, Superintendent. Steamer "BLAKE," , U.S.N., Commanding. , 18 WATER SPECIMEN. Locality .- . Date : Lat N., Long W. No. of specimen , Line With what apparatus obtained: Depth of sounding ._ Fms. Depth of specimen: Fms. Specific gravity at temperature of Fahr. n the serial U. S. COAST m GEODETIC SURVEY, Steamer " BLAKE." Locality : Date: , 18 . Lat...^ N., Long W. No. of specimen , Line DeptTi: Fms. Character of specimen: With what apparatus obtained : REMARKS ON WATER-CUPS, WITH SPECIAL REFERENCE TO THE SIGSREE WATER-CUP. Water-cup or water-bottle is the name generally applied to the instru- ment by means of which sub-surface water specimens are obtained. The work required of the cup or bottle, at any cast, is to bring a specimen from the greatest depth which the instrument reaches. Nearly all kinds of water-cups are provided with valves which are kept open by the resistance of the water during the descent, permitting a current of water through the cup, and which, on the ascent, are closed by their own weight or by the resistance of the water, thus preventing a reverse current from ejecting the inclosed specimen. With the exception of the Sigsbee water-cup, shortly to be described, there is no instrument known to me with the use U. S. COAST SURVEY DEEP- SEA SOUNDING AND DREDGING. WATER SPECmEN CUP FOR GETTING A SINGLE SPECIMEN AT EACH HAUL; INDEPENDENT POPPET VALVES: USED IN THE COAST SURVEY FOR A NUMBER OF YEARS. SPECIMENS, DENSITIES, TEMPERAT[JRES, AND CUREENTS. 91 of which, collectively, unimpaired specimens may be secured from more than one depth at a single cast. Leaving the Sigsbee cup out of consideration, the water-cups in gen- eral use may be divided into two classes — viz, free-valve and lock-valve cups. In the former, the valves are free to act during all stages of the cast, but the valves of the latter fall and lock- immediately at the first ascending movement through the water. In order to use water-cups collectively it is necessary to make stoppages for the purpose of clamping the successive cups to the rope during the operation of paying-out; and afterwards, when hauling back, a separate stoppage must be made to remove each cup as it comes to the surface. The rising and falling of the ship, which imparts a corresponding movement to the submerged water-cups, must be accepted as a condition attendant on the work ; hence all free- valve cups are liable to empty their contents at any stoppage on the ascent, and lock-valve cups may have their valves closed and locked at the first stoppage during the operation of paying out. A short time before he was detached, my predecessor in command of the "Blake" had been directed by the Superintendent of the Coast and Geodetic Survey to give special attention to the collection of water speci- mens from serial depths at various stations in the Gulf of Mexico, particu- larly off the mouth of the Mississippi River. The great delay on our lines of soundings which would result from the use of ordinary water-cups to the extent demanded by our instructions was at once apparent. The only form of cup that had previously been supplied to the "Blake" was of the kind shown on Plate 19. This had independent poppet-valves, and therefore belonged to the free-valve class. To meet this exigency in our work it appeared that some form of lock-valve cup should be designed, the use of which, collectively, would obviate the necessity of multiplying the casts for each station at which water specimens were to be obtained. It was an indispensable requisite that the proper action of the valves of such cups should be independent of the oscillations of the ship; that the valves should be free to open during the whole period of paying out, and that they should be kept closed or locked from the time of beginning the ascent. Soon after joining the "Blake" I devised a cup which in its working seemed 92 DEEP-SEA SOUKDING ANB DEEDGING. to satisfy these conditions. This cup was improved from time to time, and is herein shown in its latest form. (Plates 20 and 40.) DESCRIPTION OF THE SIGSBEE WATER-CUP. (Plate 40.) In Appendix No. 55, page 192, United States Coast Survey Report for 1854, is published a report by Assistant J. E. Hilgard concerning the action of sea-water on the metals used in the construction of certain instruments which, by the sinking of a Coast Survey schooner, had been submerged three weeks in five fathoms of water: Assistant Hilgard makes this remark : ''German silver, an alloy of copjper and nickel, was not tarnished in the least degree, nor did it become so when afterwards exposed to the air without being cleaned with fresh water J' Probably the economy effected by using water-cups collectively would warrant the expense of making them wholly of German silver, although in the Sigsbee water-cup it is employed only for the more delicate working parts, the action of which might be seriously affected by corrosion, and the cleaning of which would be difficult. All parts not specified in the follow- ing description as being made of German silver are of brass. The cylinder A (Figs. I, II, III, IV, V). The thickness of metal to be no greater than is required for tlie turning of a strong screw-thread at The lower valve-seat B (Figs. I, II, III, IV, V), which screws to the cylinder by a right-hand screw-thread. Though the lower valve-seat may be removed, this is not necessary for cleaning; there being no sharp angle at its inside junction with the cylinder, a cleaning rag thrust into the cylinder from above may be made to reach all parts. The detachable upper valve-seat C (Figs. I, II, III, IV, V). This is made detachable that the valves may readily be removed for cleaning the parts. The upper poppet-valve D (Figs. I, II, III, IV, V) and the lower pop- pet-valve E (Fig. I), connected by a stem, the valves being adjustable by means of a long, fine screw turned on the connecting stem at F (Fig. I) . The connecting stem should be made of the same material as the cylinder and the valves, so that all may expand or contract in the same proportion under change of temperature. It should not be secured to the lower valve by passing through it, thus making a joint through the valve, but should be fastened with a screw, as shown faintly in Fig. I, the threads then being soldered. The stem proper of the lower valve is squared at its lower end for tlie reception of a clock-key or crank, that the valves may be adjusted to their respective seats. K O 2: S > H w to o SPECIMENS, DENSITIES, TEMPEKATUEES, AND OUEEENTS. 93 A small German-silver compression-spring at G (Fig. I). To prevent a too easy disturbance of the adjustment of tlie valves, for which purpose the sj>iiiiff should be under a considerable pressure when the valves are adjusted. The frame-work H (Figs. I, II, III, IV, V), fastened to the cylinder by a left-hand screw-thread, inclosing the upper valve-seat. A left-hand thread is employed that the action of the spring-cliimp (to ))e referred to hereafter) nuiy not open the joint. The parts forming the joint should be ground into place to nuxke a close contact. The German-silver removable sleeve I (Figs. I, III) . To permit the removal of the propeller-shaft from its bearings. The brass pin J (Figs. I, II, III, IV, V). The German-silver shaft K (Figs. I, II, III), with rifjM-liand screw- threads (forty-four to the inch) at L and M (Fig. I). A German-silver propeller or fly; composed of two bent blades N, N (Figs. I, II), the hub (Figs. 1, II, IV), the inside screw-thread P (forty- four to the inch) (Fig. 1), the guide-cap Q (Figs. I, 11, IV), removable, but fitting tight on the hub ; and the beveled lugs R, R (Figs. I, 11). The lighter the i)ropeller the liettt-r. as will be seen hereafter. The pitch of the propeller will also be referred to further on. The guide-cap and the l(j\\vr end ot the hub are made to fit close enough on the shaft to prevent grit or dirt from getting inside and among the screw-threads, but they should be capable of sliding verij freely on the shaft. The threads of the hub and shaft should work together so freely as to permit the propeller to be revolved by a puff from the breath. The German-silver bouching S (Fig. I), soldered to the frame-work. A German-silver screw-cap, with milled head T, T (Figs. I, II, IV), beveled slots U, U (Figs. I, II), and inside screw-thread V (Fig. I). The cap should fit the shaft in the manner described for the propeller-hub. Between the screw-cap and the bouching S there slioidd be a considerable clearance, xho i"t-h or more. A clamp composed of the two lugs W, W, the pivot-screw X, and the German-silver or steel sprimj-wire Y (Figs. Ill, IV, V). If these clamps : le with the tipper arm of the levi er a decided loop, a^ -, shown ou the thermoui cases (Plates "2 an SPECIMENS, DENSITIES, TEMPERATURES, AND CURRENTS. 109 the retreat of the mercury the index remains at the highest point reached. The bottom of the index, being the part which has been in contact with the mercury, gives the point at which to take the reading. It was found that instruments made as described were liable to con- siderable error, in excess, amounting sometimes to as much as ten degrees in deep casts, due to the pressure of the water ; the pressure, by compress- ing the large, full bulb, forced part of the contents into the capillary tube, producing the same result as an increase of temperature.* In April, 1869, Dr. D. A. Miller, vice-president of the Royal Society, proposed surrounding the larger bulb by another bulb, the latter to provide a shield for the former. All thermometers styled Miller-Casella are con- structed with this outer bulb, which is fused to the stem or capillary tube just below the inner bulb. The space intervening between the two bulbs is nearly filled with alcohol, a small portion or bell containing only rari- fied air and the vapor of alcohol. The space filled by the air and vapor receives any of the spirits that may be displaced by the compression of the outer bulb. Thus the inner bulb is almost wholly relieved from pressure, and the alcohol serves as a medium for the transmission of temperature. Dr. C. Wyville Thomson, now Sir C. Wyville Thomson, estimated from the results of experiments with a number of the protected instruments that their mean error due to pressure was as follows : For 250 fathoms, 0°.079 C. ( = 0°.142 F.). For 2,500 fathoms, 0°.79 C. (= 1°.42 F.). These, if applied as corrections, are subtractive. Of thirty-six Miller-Casella thermometers recently purchased by the Coast and Geodetic Survey, the mean error of all due to a pressure of three and one-half tons was l°.l Fahrenheit, as ascertained by the makers. The greatest single error was 1°.7 and the least 0°.6. The instrument attached to its frame is kept, both for stowage and use, in a perforated copper case. As provided by the manufacturers the case must be attached to the rope by stops, but all of the "Blake's" cases are fitted with the spring-clamp shown on Plates 2 and 3. *For an interesting and instructive d^escription of the Miller-Casella thermometer, see "Depths of the Sea," by Dr. C. WyvUle Thomson, pp. 288-299. 110 DEEP-SEA SOUNDING AND DEEDGING. The Miller-Casella thermometer is made by L. Gasella, scientific instrument maker, 147 Holborn Bars, London, E. G. The catalogue price of the instrument is £2 5s,, with case and magnet. REMARKS CONCERNING THE MILLER-CASELLA THERMOMETER. There can be but little doubt that the Miller-Casella thermometer? when properly managed, gives in most cases a close approximation to the temperature of the depth to which it has been lowered, but the immobility of the indices, after the retreat of the mercury, being dependent on friction alone, is not absolutely assured, and herein, perhaps, lies the chief objec- tion to the iiibtrument. There is nothing in its appearance to point out an error in this respect when it has occurred. The only safeguard, when but a single instrument is used for each depth of a series, is to compare carefully the indications at the same or different series of observations, the surest means of doing this effectually being to construct curves like those shown on Form 14 (Chapter VI). When all the indications of a set of serial observations are correct the gradients of the curve sometimes change rapidly, but a decided angu- lar deviation from the general contour of the curve is perhaps nearly always due to an erroneous record by the instrument. Sometimes a particle of mercury gets above an index, or one of the latter becomes immersed in the mercury; an index becomes jammed in the tube, or the column of mercury breaks. These are mere accidental defects, which, being apparent to the eye, point directly to an error, and they may in most cases be remedied on board the vessel. When a particle of mercury gets above an index the latter may be drawn by the magnet into an enlargement or swelling of the tube, which all of these thermometers have just below each bulb ; the mercury will then fall clear. When a column of mercury breaks, its integrity may be restored by placing the instrument in warm water or by gently tapping the bottom of the frame against some resisting substance, both of which methods require caution. On one occasion, in my experience, when the water was too warm there was a general disturbance inside the tube, which ruined the instrument ; it was, perhaps, caused by part of the compressed §" S H ^ ^ S S >ci >T3 ^' I. 2^^ -■ Sow ffi r S > SPECIMENS, DENSITIES, TEMPEEATTJEES, AND CUEEENTS. Ill air being carried by expansion into the opposite limb. The tube is almost certain to become loosened on the frame by the tapping process, which reminds me of a detail in the construction of the instrument that brings about much annoyance. The fastening which is intended to hold the tube in place on the frame is a soft copper band passing half around the tube at the bottom of the bend and fastened only by one end to the frame. The object of this is probably to allow for the expansion of the glass, and to give a slight cushioning — enough to prevent the tube from breaking in the event of a violent shock such as would be caused by the case striking on hard bottom, but in prolonged work — or in tapping the frame — it per- mits the shifting of the scale, sometimes as much as li°. For several years after construction thermometers undergo a change which results in a displacement or ''elevation ' of the zero point, sometimes amounting to as much as 2°, making the indications too low. There is a scratch on the tube of the Miller-Gasella thermometer at or near the freez- ing point, and others at intervals of 20°. These are probably made in the process of calibrating the tube. Should the scale shift, the scratch nearest the freezing point, or any other, may be made use of to effect a readjust- ment, if the point on the scale to which it corresponds has been previously ascertained. On board the "Blake" all attempts to extricate an index which had become immersed in mercury were unsuccessful. An index jammed in the tube may sometimes be cleared by alternately tapping the frame and using the magnet. If it can be drawn up into the enlargement of the tube already mentioned it may be found in working order when again drawn down. Tapping the frame or swinging it about the head for the same purpose should not be allowed except as a last resort, and then only in the presence of the person charged with the care of the instruments, who should verify the correctness of the scales afterwards, A great advantage afforded by the Miller-Casella thermometer is its adaptability to collective use; that is, it may be used to obtain tempera- tures at various depths at a single haul, by employing it in any number desired, one or more at the several depths of a series. Although the instru- ment sometimes records erroneously through the disturbance of the index, 112 DEEP-SEA SOUNDING AND DEEDGING. several of them lowered to the same depth would, by checking each other, make the probability of error in this respect very remote. Under certain relative thermal conditions of air and water a maxi- mum and minimum thermometer may not give trustworthy indications when set as usual — that is, at air temperature. We will consider an actual case from the "Blake's" work: Air 51 Water : Surface 71 50 fathoms 63 100 fathoms 60^ 200 fathoms 50 The indices of all the instruments are set at 51°, the temperature of the air. The instruments at fifty and one hundred fathoms will not indi- cate the temperature of their respective depths by the minimum scale, because the mercury in the minimum limb will retreat from the index in water which is of a higher temperature than that at which the instruments were set. The maximum scale may give true indications at those depths if in the passage of the instruments through the warmer upper strata the indices are not carried above 63° and 60i° respectively. This is merely a case at hand, but it shows that other cases might arise in which much would be left to conjecture. The way in which we managed to make the Miller-Casellas serve our purpose in this and similar instances was to immerse them in warm water, raising their temperature considerably above that of the air; then, after setting them while in the warm water, to attach each in turn quickly to the rope and lower it at once into the sea. The minimum scales then gave acceptable readings. The case already presented is a representative one of a class, and a general rule may be stated as follows : The tempera- ture of a stratum which is at once colder than the strata above and warmer than the air will not be indicated at all by the minimum scale, and often only with uncertainty by the maximum scale. From what has been said it is seen that a maximum and minimum thermometer is not well adapted to ascertaining the temperature of inter- mediate warm or cold strata. SPECIMENS, DENSITIES, TEMPERATUEES, AND CURRENTS. 113 An important matter to know when using any thermometer in deep-sea operations is the time that it requires to take up any change of tempera- ture. The Miller-Casella thermometer, being protected by the outer bulb, is sluggish in its action, particularly as its indication nears the temperature of the surrounding medium. Commander Lester A. Beardslee, U. S. N., made a series of experiments with the Miller-Casellas while on duty with the Commission of Fish and Fisheries. Through the courtesy of Prof. Spencer F. Baird, Commissioner, I am enabled to give one of Commander Beardslee's tables. In each case the Miller-Casella and a standard were simultaneously placed in a bath, the temperature of which was lower than the temperature indicated by the instrument at the instant of immersion. Commander Beardslee thus describes the standard thermometer used for comparison : " A mercurial standard, made by L. Casella, of London, No. 7432, reading from zero up to 120°, on a scale marked on the glass, and twelve inches long, giving 10° to the inch; bulb cylindrical, .75 of an inch in length. No mounting." Concerning the ice-bath tests, the last two of the series, he says : "In test No. 1, in ice, the instrument (Miller-Casella) was placed on its back in a trench out in the ice, and the bulbs covered with pounded ice. The mercury corresponded in its action very closely to the action of a bath of 50*^ until it reached that point. " In test No. 2 the upper portion of the ebonite guard was removed, thus letting the crushed ice come into immediate contact with the upper portion of the bulbs. This induced quicker action, but still slower than a bath of 35°, and at last, as in former cases, the mercury apparently ceased to fall at 35°." These and other experiments with the Miller-Casellas, by Commander Beardslee, are given in Appendix C, Report of the Commissioner of Fish and Fisheries for 1877, Prof. Spencer F. Baird, Commissioner. 15 D s 114 DEEP-SEA SOTJNDING AND DEEDGmG. Experiments with Miller-Casella No 1844. Bath, 60°. Bath, 55°. Bath, 50°. Bath, 45°. Bath, 40°. Bath, 35°. Ice-bath, 32i°. Ice-bath, 32*°. •3 1 1 1 1 1 i 1 1 1 g t 1 1 1 1 1 1 1 1 1 1 a ■s 1 o' 06 20 40 1 00 1 20 1 40 2 (JO 2 40 3 00 5 00 6 00 8 .00 9 00 H 00 7C 60 60 GC 6C 60 5 5 5 5 68 67 66 65 64 "^ 62 61 61 61 61 2 5 8 2 70 55 55 55 55 65 55 55 55 55 55 55 70 64 62 59 58 57 56 55 55 55 55 55 5 5 2 2 6 2 7C 50 5C 50 50 50 50 50 50 50 50 50 2 2 5 5 2 2 4 7( 65 63 59 58 56 55 52 52 51 51 51 5 6 6 2 2 2 70.0 45^0 45.0 45^0 45.0 id'.d 45.0 45! 45.0 45! 44.8 45! 45.0 4.5.0 70.0 67.5 56] 54! 53.0 is'.s 47.5 46! 46.0 45.' 8 45.8 7C 40 40 40 40 40 40 4C 39 4C 2 2 2 2 1 2 2 7C 59 56 54 52 4E 44 42 41 41 40 40 5 4 1 2 2 6 70.0 3416 34.6 3416 34.6 35! 35.0 35.0 34.6 34.6 34.8 34.5 34.5 34.5 34.5 70 58 48 44 43 42 37 35 35 34 34 5 5 5 5 '5 5 70 38 32 32 32 32 32 32 32 32 32 32 32 32 32 32 32 5 5 5 5 5 5 5 5 5 5 5 5 67 63 58 57 56 54 52 50 49 45 43 40 39 35 5 8 2 5 5 5 70.0 32.5 32.5 32.5 32.5 32.5 32.5 3215 32.5 32.5 32.5 32.5 32.5 32.5 32-5 32! 5 32. ,5 70 66 57 54 5C 48 46 4C 37 37 36 3« 35 35 35 35 12 00 14 00 15 00 22. 00 . .. - 6 1 32.5 25 00 It should be remembered that a tliermometer in actual use at sea is recording during the descent, which may be taken into account in time allowance. It will also register changes more quickly when passing through water than when resting in a still bath. DESCmPTION OF NEGRETTI & ZAMBRA's DEEP-SEA THERMOMETER. (Plates 21, 22, and 23.) The following description of this thermometer is copied from the cata- logue of the makers, Messrs. Negretti & Zambra, Holborn Viaduct, Lon- don, E. C. This is done for convenience, not necessarily as an expression of my opinion. The few words interpolated by me are inclosed in brackets. The letters of reference employed in the catalogue, being only three in number, are retained, although the plates given in this book are not lettered. Negretti & Zambra's thermometer in a very different shape was sent us for trial, on board the " Blake," during the early part of my command, but it was so cumbersome, expensive, and left so much open to doubt in its indications, that it was reported on adversely to the Superintendent of the Coast and Geodetic Survey. Since then the makers have issued it in a SPECIMENS, DENSITIES, TEMPEEATURES, AND CURRENTS. 115 shape that seems to promise much in the way of correct results. It is still open to some improvement, even for taking a single temperature at a haul, and it cannot be used collectively like the Miller-Casella, although it is probably more trustworthy when used singly. This late form of the instru- ment has been used in the Caribbean Sea and Passages by the "Blake" under the command of Commander Bartlett, and also in the Arctic Sea by the Norwegians. "The construction of this thermometer will be readily understood by reference to [Plates 21 and 22]. The bulb is cylindrical, and mercury is the thermometrical fluid. The neck of the bulb is contracted in a peculiar manner at A [immediately below the bulb], and upon the shape and flneness of this contraction the success of the instrument mainly depends. Beyond A the tube is bent, and a small catch reservoir is formed at B [in the bend], for a purpose to be presently- explained. At the end of the tube a small receptacle, C, is provided. When the bulb is downward the glass contains sufficient mercury to fill the bulb, tube, and a part of the receptacle C. if the temperature is higlu leaving sufficient space in C. ^Vhen the thermometer is held bulb upward the mercury breaks at A, but by its own weight flows down the tube, filling C and a portion of the tube above C in relation to the existing temperature. The scale accordingly is made to read upwards from C. To set the iustruuieut for observation it is only necessary to place it bulb downward, then the mercury takes the temperature just as au ordinary thermometer. When at any time or at any place the temiierature is reijuired. all that has to be done is to turn the thermometer bulb upward and keep it in this position until read oft'. The reading may be taken at any time after, for the quantity of mercury in the lower part of the stem which gives the reading is too small to be sensibly influenced by a change of temperature, unless it is very great, while that in the bulb will continue to contract with greater cold and to expand with greater heat, and in the latter case some mei-cury will pass the contraction A and may fall down and lodge at B [in the catch reservoir], but it cauuot go further so long as the bulb is upward, and thus the temperature to be read ott' will not be vitiated. Now, whenever the thermometer can be handled it can readily be turned bulb upward for reading off the existing temperature. It must be clearly understood that the thermometer is only intended to give the temperature at the time and place when and where it is turned over; it is simply a recording thermometer ; it cannot be used as a self-registering maximum or minimum, though it could be constructed to act as a maximum if required. But at a depth in the sea some contrivances must be provided for turning the thermometer bulb upward. For this purpose the thermometer is fitted into a wooden frame, loaded with shot, free to move from end to end of it, and heavy enough to render the whole instrument just buoyant in "In using the thermometer a cord is rove through the hole in the frame nearest the bidb, and the instrument is fastened by this cord to the sounding-line. In descending the thermometer will be pulled down with the bulb downwards [Fig. 1, Plate 23], but upon being pulled up the instrument, owing to the resistance through the water, and consequent displacement of its center of gi-avity, will turn over and come up bulb uppermost [Fig. 2, Plate 23] ; the temperature of the spot where it turned over will then be indicated. "As regards the thermometer itself, it was necessary, in order to make it perfectly satisfactory, to protect it against pressure, even if intended for shallow seas as well as for the deepest. For whether used in deep or shallow water, unless withdrawn from pressure, its indications would always be more or less in error. Like an ordinary thermometei-, it is devoid of air, and so quite different from Sixe's, which, containing compressed air, has a certain internal resistance. Hence it would be more affected by pressure than Sixe's, however thick the glass of the bulb. By the simple expedient of placing the thermometer entirely in a shield of glass hermetically sealed the effect of external pressure is entirely eliminated. The shield must, of course, be strong. It need not be exhausted of air. It must, however, render the enclosed thermometer more difficult to be affected by changes of temperature ; in other words, it will make it sluggish. "To counteract this sluggishness in that portion of the shield surrounding the bulb some mercury is introduced and confined there by a partition cemented in the shield around the neck of the thermometer 116 DEEP-SEA SOUNDING AND DEEDGING. bulb. This mercury acts as a carrier of heat from the exterior of the shield to the interior of the thermometer ; and the efficacy of this arrangement has been experimentally determined, the instrument thus protected being, in fact, far superior in sensibility to Sixe's thermometer. "So long as the shield withstands the pressure — that is, does not break — the thermometer will be unaffected by pressure, and there is abundant experience to show that siich a shield will stand the pressure of the deepest ocean. The greatest pressure can never afiect a thermometer so protected. Doubtless the shield will be compressed a little under great pressure, but this can never exert an internal pressure suffi- cient to have an appreciable effect upon the thei-mometer. This method of shielding is quite efficacious, and deep-sea thermometers so protected do not require to be tested for pressure in the hydraulic press. The thermometer will simply require to be tested for sensitiveness and for errors of graduation very accu- rately, because it is a standard instrument adapted to determine very small differences of temperature as well as large ones, even one or two tenths of a degree in shallow waters. The test for sensitiveness should determine how many seconds the instrument requires to take up a change of five degrees rise or fall, and the time has been found from five to ten seconds. "A considerable number of these instruments have already been tested at the Kew Observatory with perfectly satisfactory results, which place beyond doubt their value as standard deep-sea thermometers. "Thus, provided the turning-over gear is found to answer, this instrument evidently possesses great advantages. It has no attached scale, the figuring and graduations being distinctly marked on the stem itself, and the shield eftectually preserves them from obliteration by sea-water. The part of the stem which forms the background to the graduations is enameled white to give distinctness to the mercury. "The hole at the top of the frame is for the purpose of lowering and keeping the thermometer upright until it has reached the water. This is effected by putting a cord through the hole and both ends of it kept in the hand until the thermometer has reached the water, then one end is let go and the cord pulled on board. This operation is not imperative', but it saves the thermometer from being knocked about previous to reaching the water. "Price for Negretti & Zambra's new patent standard deep-sea thermometers, £2 10s." REMARKS CONCERNING NEGRETTI & ZAMBRA's THERMOMETER. Previous to their use on board the "Blake" Prof. Spencer F. Baird had used them in the work of the Commission of Fish and Fisheries as deep as two hundred fathoms, and thought highly of them. Commander Bartlett, while thinking well of them, found that their wooden cases when recovered from eight hundred fathoms were com- pressed and shriveled. The pressure at eight hundred fathoms is about one ton on a square inch. Prof. J. E. Hilgard suggests that the wooden case might be replaced by a case of thin metal, filled with paraffine. The Superintendent of the Coast and Geodetic Survey wishing to make a preliminary trial of them in actual use in advance of reports from Commander Bartlett, a few experiments were carried out by Lieut. S. M. Ackley, commanding the Coast Survey schooner "Eagre." The following describes some of these experiments: Experiment No. 1. — Lower the mercury to freezing point (32°), then reverse, bringing the bulb uppeiTOOSt. While retained in that position submit the instrument to a temperature of about 85°. Note if the catch reservoir wholly or partially fill, and if it overflow at what temperature as indicated by the instrument. Jieport. — "The catch reservoir partially filled but did not overflow." U. S COAST SURVEY. DEEP- SEA SOUNDING AND DREDGING. DESCENDING-. ASCENDING. THE NECRETTI-ZAMBRA DEEP-SEA THERMOMETE"R IN USE. SPECIMENS, DENSITIES, TEMPEEATUEES, AND CUEEENTS. 117 An instrument in the ascent from deep water will pass through water of a higher temperature than that in which it reversed; hence the catch reservoir will contain some mercury on arriving at the surface. In experi- ment No. 1 a temperature higher than 85° might have been chosen, but other experiments have shown that the catch reservoir will not be made to overflow by any higher temperature to which the thermometer would be exposed in work at sea. Experiment No. 2. — With the catch i-eservoir partially filled, as in experiment No. 1, tilt the thermometer case and slap it roughly. Note if any of the contents of the reservoir pass down into the tube; also if the bulb discharge any more mercury into the reservoir under this treatment. Report. — "None of the contents of the reservoir passed down into the tube. Bulb did not discharge more mercury into the tube." Experiment No. 3. — Lower three Negretti & Zambra thermometers, attached as nearly as may be to the same place on the rope, to a depth of 500 fathoms, and haul back without stopping at that depth or at any point on the ascent. Note the indications given by each instrument. Beport. — "Instrument No. 4, 47°. 5; instrument No. 5, 47°. 5; in.strument No. 6, 47°. 5." Experiment No. 4. — The same as experiment No. 3, excepting to delay seven minutes at the depth of 500 fathoms before hauling back. •JJepor*.— "Instrument No. 4, 46°.2; instrument No. 5, 46°.2; instrument No. 6, 46°.2." Experiment No. 5. — The same as experiment No. 3, excepting to delay seven minutes at 500 fathoms, and again seven minutes at 300 fathoms on the ascent. Sepoi-t.—" Instrument No. 4, 47°; instrument No. 5, 60°; instrument No. 6, 47° — vessel drifted quite fast, so that the line was at an angle." Experiment No. 6. — At that same station and in as limited a time as practicable take temperatures at 150, 300, and 500 fathoms, by a separate haul for each depth, without stopping on the ascent. Then with the same instruments take temperatures simultaneously at the same depths by using a separate thermometer, attached to the same rope, for each depth; this will require stoppages both in paying out and in hauling back for the pur- pose of attaching and removing instruments. Beport. — "Taken separately at 150 fathoms : Instrument No. 4, 68°; instrument No. 5, 67°.5; instrument No. 6, 68°. "Same at 300 fathoms: Instrument No. 4, 54°. 5; instrument No. 5, 54°; instrument No. 6, 54°. 5. "Same at 500 fathoms: Instrument No. 4, 46°. 5; instrument No. 5, 46°. 5; instrument No. 6, 46°. 5 "Taken simultaneously: At 150 fathoms, instrument No. 4, 75°. 5; at 300 fathoms, instrument No. 5, 59°.5 ; at 500 fathoms, instrument No. 6, 64°." During the course of the experiments the vessel was pitching moder- ately. The difference between the indications obtained at the separate casts in experiments Nos. 3 and 4 may have been partially due to the inclination of the line caused by the drifting of the vessel, the ''Eagre " having no steam. Experiments Nos. 5 and 6 show that a stoppage during the ascent is inadmissible, and that the thermometers must not be used collectively, in the sense in which I have employed that term. In experiment No. 6, at the separate casts, instrument No. 5 gave a temperature 0°.5 lower than instruments Nos. 4 and 6, both at one hun- 118 DEEP-SEA SOUNDING AND DEEDGING. dred and fifty fathoms and at three hundred fathoms. Since all had agreed in the first and second experiments, it is highly probable that instrument No. 5 was somewhat defective in its construction, and that the column of mercury did not break at precisely the same point in the tube each time on reversal. Surgeon Jerome H. Kidder, U. S. N., assigned to duty with the Commission of Fish and Fisheries, found this defect in one or more of Negretti & Zambra's thermometers, but he was afterwards informed by Prof H. Y. Hind that the makers had given assurances of greater correct- ness in the latter instruments. It is uncertain how, in experiment No. 6, ^' taken simultaneously,'' the indications 75^5, 59°.5, and 64° occurred, as each instrument would have been expected to give an approximate temperature of the depth at which the last stoppage was made on the ascent — one hundred and fifty fathoms = 68°. Perhaps a short stoppage may have been made, inadvertently, as instrument No. 4 was near the surface, which would account for its indi- cating 75°.5. Instruments Nos. 5 and 6 evidently reversed at some inter- mediate point below one hundred and fifty fathoms, but not at that depth. Dr. Kidder found that while niost of the Negretti & Zambra deep-sea thermometers had been carefully calibrated, one or two notable exceptions occurred in his comparisons, in a single instance producing at one point of the scale an error as great as 2°. The instrument is perfectly protected against pressure so long as the outer casing remains intact. SPECIMENS, DENSITIES, TEMPEEATUEES, AND CUEEENTS. 119 COMPARATIVE TEST OF THE MILLER-CASELLA AND SEA THERMOMETERS. NEGRETTI & ZAMRRA S DEEP- Atmy request, Prof. J. E. Hilgard had the following comparative -tests for sensitiveness made at the Coast and Geodetic Survey Office by Mr. W, Suess. Time. Time. Time. Standard. Miller- Casella. Negretti & Zambra. H. M. H. M. H. M. o 9 24 40.0 9 28 40.0 9 25 40.0 30 40.0 30 40.0 30 40.0 32 34 50.0 50.0 34 50.0 60.0 —3-4"' 49.0 '" 60.0 60-0 38 60.0 38 58.6 "" 38 60.0 70.0 40 67.0 69.9 42 70.0 42 69.0 42 70.0 80.0 79.0 45 46 80.0 46 79.5 46 80.0 49 90.0 49 88.5 60 90.0 50 89.0 j 60 89.0 66 90.0 66 90.0 53 90.0 10 00 90.0 10 00 90.0 10 00 90.0 02 - 83.0 04 80.0 04 81.3 04 80.0 06 70.0 74.0 08 10 70.0 60.0 08 10 72.0 08 10 70.0 60.0 12 60.0 12 61.8 12 60.0 14 50.0 14 53.6 14 49.9 16 18 50.0 16 51.1 46.5 16 18 49.9 40.0 20 40.0 20 42.5 20 40.0 24 40.0 24 40.0 24 40.0 The instruments used were a Casella mercurial standard (unprotected), No. 13416; a Miller -Casella deep-sea thermometer. No. 31488; and a Negretti & Zambra's deep-sea thermometer. No. 42665. These instruments were placed in a bath of 40°, and at 9^" 30™, when all had acquired the temperature of the bath, the experiment was carried forward. Readings were taken every four minutes, as shown by the large figures in the "time" columns. Immediately after each of these readings warm water was added in sufficient quantity to raise the temperature of the bath 10°. The small figures in the "time" columns show the readings of the several instruments at the instant the standard had acquired the changed temperature of the bath. After the standard had reached 90°, time was 120 DEEP-SEA SOUKDING AOT) DEEDGING. allowed for the deep-sea thermometers to acquire this temperature; then, at lO*" 00"" the character of the experiment was changed and the tempera- ture of the bath was gradually lowered to 40°. The previous system of times and changes was adhered to, but the process was exactly reversed. These tests show Negretti & Zambra's deep-sea thermometer to be more sensitive than the Miller-Gasella deep-sea thermometer. If the former is as well protected against pressure as the latter, it is the better instrument in regard to the quality of sensitiveness. A STANDARD THERMOMETER FOR COMPARISON; HOW TO SELECT ONE. All thermometers should be compared with a standard when received for use on board ship, and the operation should be repeated from time to time. It is well to provide a standard which has been thoroughly tested by an expert, but, if necessary, any mercurial thermometer of first quality, having wide divisions, a full-range scale marked on the tube, and which is known to be several years old, may be made to serve for the purpose by carefully verifying its graduation. An old thermometer should be chosen in order to avoid the "elevation of the zero point" that thermometers undergo for several years after manufacture. The freezing and boiling points are the fixed points on which the whole graduation depends, and they may be tested with but little trouble. Melting ice or snow always gives the point of freezing, 32° of the Fahrenheit scale. Provide any vessel which will hold a good quantity of crushed ice, and which will admit of an unobstructed escape of the water from the bottom. A copper cylinder with an inverted-cone bottom, having a hole in the apex, may be used; or an ordinary water-cooler open at the top and having a spigot at the bottom will suffice. Surround the thermom- eter with crushed ice nearly up to the mark of 32°, and let it stand there for fifteen minutes in a place having a temperature above 32°, for the ice must be in a melting condition. At the end of this time note the height at which the mercury stands. The point reached is that of 32°, or the freezing point. Next the boiling point, 212° of the Fahrenheit scale, must be deter- mined, and this is done by placing the thermometer in the vapor arising SPECIMENS, DENSITIES, TEiMPERATUEES, AND CURRENTS. 121 from boiling water. An apparatus and the method of proceeding are described in Ganot's Physics. The cuts and the text used herein for describing this part of the operation are copied from that work. F.— Apparatus THE BOILING POINT OF THERMOMETERS. "In both, the same letters designate the same parts. The whole of the apparatus is of copper. A central tube, A, open at both ends, is fixed on a cylindrical vessel containing water; a second tube, B, concentric with the first, and surrounding it, is fixed on the same vessel, M. In this second cylinder, which is closed at both ends, there are three tubulures, a, E, D. A cork, in which is the thermometer t, fits in a. To E a glass tube containing mercury is attacljed, which serves as a manometer for measuring the pressure of the vapor in the apparatus. D is an escape tube for the vapor and condensed water.* "The apparatus is placed on a furnace and heated till the water boils; the vapor produced in M rises in tube A, and passing through the two tubes in the direction of the arrows, escapes by the tubulure D. 'J he thermometer, t, being thus surrounded with vapor, the mercury expands, and when it has become stationary •the point at which it stops is marked. This is the point sought for. The object of the second case, B, is to avoid the cooling of the central tubulure by its contact with the air." In the following paragraph I quote from Ganot, but have changed his figures to suit the units of measure adopted in this book: " The determination of the point 212° Fahrenheit would seem to require that the height of the barometer during the experiment should be thirty inches, for when the barometric height is greater or less than this quan- tity water boils either above or below 212°. But the point 212° may always be exactly obtained by making a correction introduced by M. Biot. He found that for every 0.6 inch difi'erence in height of the barometer there was a difference in the boiling point of 1°. If, for example, the height of the barometer is 30.4 inches, that is, 0.4 inch, or two-thirds of 0.6 above 30 inches, water would boil at 212|°. Consequently 212|^° would have to be marked at the point at which the mercury stops." * The glass tube may be dispensed with when a barometer is at hand, if there is a free escape for the 16 D S 122 DEEP-SEA SOUNDING AND DEEDGING. In the manufacture of thermometers the tubes are first tested to ascertain if the bore or chamber of the capillary tube is of the same caliber throughout its whole length. When a tube is found to be perfect in this respect, it only requires to be divided into one hundred and eighty equal divisions (212°-32°) between the boiling and the freezing points, that each division may correspond to one degree of temperature; but when the tube is not perfect it needs to be calibrated. In this process a short column of mercury being introduced into the tube, the latter is manipu- lated so that the mercury may be moved about from place to place. The length of the column at different localities is marked on the tube, which is thus divided into sections of equal capacity, although it may be of different length. Each section is then subdivided, independently, into degrees. In selecting a standard .the instrument should be tested for calibration thus : Hold the tube in a horizontal position over the flame of a spirit-lamp so that the heat may be concentrated on the tube at a point about an inch or more from the end of the column of mercury, or, better, direct the flame to that point with a blow-pipe, observing caution. In a short time remove the tube from the flame, and, still holding it horizontal, give it a slight motion as if throwing a dart, with the small end of the tube foremost. This will break the column of mercury at the heated point. Move the detached column about as in the process of calibration, noting at each change in its position the number of divisions that it spans. The number should be the same throughout if the tube has been properly calibrated in the manufacture. If any discrepancies are discovered, pursue the process until they are localized, and note the points and the quantity of error in a table. When the experiment has been carried as far as the main column of mercury, join the two portions and again break the column, this time detaching a greater length than before, which will permit the examination to be carried to a lower point on the tube. Continue the process by detach- ing in this way a greater length of mercury each time, until the whole range of the scale has been tested and the table of errors or corrections completed. It is plain that the operation may be facilitated by selecting a cool place in which to perform it, for when the mercury stands low in the tube the first length detached may be moved through a great part of the tube. SPECIMENS, DENSITIES. TEMPERATUEES, AND CUERENTS. 123 COMPARISON OF THERMOMETERS WITH A STANDARD. The graduation of deep-sea thermometers not being carried above 130° Fahrenheit, the points on the scale that may be most accurately com- pared are the freezing point and that of water at about the temperature of the surrounding air. Any change of temperature of water under such circumstances would be very slow, thereby affording opportunity for a careful comparison. Several places having different temperatures might be occupied in turn, and a number of points tested in water with great nicety. A quiet place, free from draughts, should be selected. The freezing point may be fixed independently by the melting-ice test; but by also placing the standard in ice the subsequent process of comparison may be somewhat shortened. Next make a bath of ice- water; remove the ice and immerse therein the standard and the instru- ments to be compared, keeping the bulbs on the same level. Let the water become gradually warmer, reading off from time to time; or the operation may be more quickly completed by occasionally adding a little warm water to the bath, which must be stirred almost constantly to preserve an even temperature throughout. Thermometers suitable for standards are much more rapid in acquiring the temperature of the sur- rounding medium than the Miller-Casellas, 'which, by being protected against pressure in the manner already described, are very sluggish, making their comparison a slow process. Before reading off the Miller-Casellas the bath should be kept for a considerable time at the same temperature by adding ice-water or warm water in small quantities, as occasion may require, and stirring vigorously. In reading off the indications the question of parallax must be con- sidered, and the eye placed on a level with the top of the column of mercury. DETERMINATION OF SURFACE AND SUD-SURFACE CURRENTS. The demands of the more prominent features of the "Blake's" work permitted only a few observations for the determination of sub-surface cur- rents, but for those at the surface we observed frequently whenever work- ing in depths not exceeding two hundred fathoms. Preceding the current 124 DEEP-SEA SOUNDING AND DEEDGING. observations, the cast for depth was made with rope, the lead weighing one hundred and fifty pounds. The depth of water having been ascertained, slack-line was payed out from the vessel, and the dinghy, in charge of the assistant-navigator, was lowered and made fast to the bight of the sound- ing-rope, after which slack-line was again payed out from the vessel that the movements of the latter might not influence the boat during the pro- cess of taking the observations. The apparatus used is shown on Plate 5. The peculiar shape of the cans shown on Plate 5 originated, I believe, with Prof. Henry Mitchell, Physical-hydrographer of the Coast and Geodetic Survey. The cans are made of galvanized sheet-iron, and in shape are, respectively, a cylinder of eight inches diameter and eleven inches height, and a cylinder of equal dimensions surmounted by a cone three inches in height. At the top of each is a small aperture. In use the aperture of the lower can is kept open to the entrance of water to facilitate the sinking of the can and to prevent it from crushing under pressure, while that of the upper can is kept closed by a cork, no water being admitted. For any observation both cans are used. They are connected by a length of sounding-wire (diameter .028 inch), and are so loaded with old scraps of lead or iron, or with pebbles, that when set adrift the lower can will sink to the full extent of the connecting wire, while the upper can will be submerged only to the base of its conical top, thus making the submerged surface of the two cans equal, which simplifies the problems relating to the determination of the sub-surface currents from the data obtained by observation. For observing surface currents the lower can is sunk to a depth of one or two fathoms, simply to counteract the effect of winds and surface-wash on the floating can; for sub-surface currents it is lowered to the depth at which it is desired to know the current, the distance being regulated by the connect- ing wire. To the upper can is attached a graduated line, marked for knots and tenths, the length of each knot being fifty and seven-tenths feet, to cor- respond to a time-interval of thirty seconds. Sometimes a few fathoms of stray-line are interposed between the floating can and the initial mark, the last being a white rag. Observations are made from the boat as a station point; those for velocity, excepting in the modification which will be mentioned, being made after the manner of observing the speed of a ves- SPECIMENS, DENSITIES, TEMPEEATURES, AND CURRENTS. 125 sel with the log-chip. The direction of the movement of a can is obtained by compass bearings from the station point. In the "Blake's" work, if only the surface current was to be observed, the apparatus taken into the boat embraced one set of two cans, the gradu- ated line wound upon a hand-reel, and the time-glass or chronoscope. The force employed consisted of two men in charge of an officer. One man fastened the boat to the sounding-line and then held the glass or chrono- scope; the other got over the cans and held the reel, while the officer read, the divisions on the line and took the bearings. The rapidity with which Mr. Peck, Master, and afterwards Lieutenant Sharrer, could accomplish this kind of work with the little dinghy, even in moderately rough seas, was remarkable. We generally made use of their observations in shaping the course. The direction and velocity of the current would be shouted to those on board the vessel before the dinghy got alongside, and the course to be steered, allowing for the current found, was generally known by the time the boat was at the davits.* When it was desired to Observe for sub-surface currents, a cutter, manned by four men in charge of an officer, was used instead of the dinghy. A spare sounding-machine, like that shown on Plate 6, was lashed in the stern of the boat, and contained the sounding or connecting wire in five or ten fathom lengths, each length having at one end a small brass thimble and at the other a small snap-hook. To join the successive lengths it was only necessary to snap the hook of each into the thimble of its neighboring length. The reel projected slightly over the gunwale of the boat; in its friction-score was laid a simple friction -line, the standing part of which was secured to the bed-board. of the machine in advance of the reel, the inboard or haul- ing part being managed by hand. To get overboard a set of cans for sub- surface observation, the lower can, after being attached to the snap-hook at the outer end of the wire, was allowed to sink rapidly, the wire paying out from the reel, which meanwhile was kept under frictional control. When the snap-hook had cleared the reel, denoting that the can had reached the * When not on our sounding-lines we occasionally took current observations for navigating purposes, if "on soundings." By resorting to this expedient we were sometimes enabled to perform, with safety, feats of piloting which otherwise would have been extremely hazardous. 126 DEEP-SEA SOUNDING AND DEEDGING. required depth, the reel was stopped, and the upper can, which had pre- viously been fitted with the graduated line, was then quickly attached to the submerged wire and set adrift. The methods of observing currents from a boat are inexact at the best, and are particularly so when a graduated line must be used; hence the mean of a number of observations should be obtained when possible. In a ''straight current," as in a river or a canal, a measured base on shore, par- allel to the axis of the stream, with ranges and theodolites at each end, has been made use of instead of the graduated line. Electric current meters have also been used successfully for determining the velocity of the lower strata in rivers and canals, but I think no meter has yet been adopted which will record the direction of sub-surface currents in ocean depths.* There will be described under Cases I and II the methods employed by the "Blake" for determining sub-surface currents, one case being a modification of the other; also, under Case III, a better method, a descrip- tion of which, with special reference to spherical floats, is given in Ap- pendix No. 26, Coast Survey Report for 1859, page 311, by Prof. Henry Mitchell. It will be observed that Cases I and II do not involve the departure of the vessel from her station near the position of the sounding, even though long delayed there, while in Case III she might be required to temporarily abandon the line of soundings in order to pick up the boat. This will explain why we did not adopt the most accurate method. Case jr.— During the whole period of observation the boat remains * Mr. Clemens Herschel, civil and hydraulic engineer, has devised some electric current meters w^hich are favorably known. They are manufactured and sold by Buff «fe Berger, 9 Province Court, Boston, Mass. These meters do not record the direction. Mr. Herschel is very sanguine of the future success of meters in deep-sea current work. His own statements in reference to the subject are here given : "Electric current meters are now made in serviceable form for deep-sea observations in this country. They have been used in ten to fifteen fathoms on the rivers connecting the great Lakes, as detailed in the several reports of the Chief of Engineers United States Army, Survey of the Great Lakes, in the years 1868 to 1872; also, in depths up to twenty fathoms on the Uruguay, Parana, La Plata, and other large rivers in South America, as described in Envy's Hydraulics of Great Eivers, E. & F. N. Spon, London and New York. A skillful observer should find no insuperable difficulty in using them at much greater depths. Several of these instru- ments could also be strung on one and the same vertical guide-wire, and simultaneous observations of the cur- rents at different depths be taken in this manner. "An instrument for observing the direction of sub-surface currents at any depth is described in the Min- utes of the Proceedings of the Institution of Civil Engineers of London, session X875-'76, Pt, HI," SPECIMENS, DENSITIES, TEMPEEATUEES, AND CUEEENTS. 127 anchored by the sounding-rope. Preceding and following the observations for sub-surface current, and, if necessary, at intermediate stages, observa- tions are made for ascertaining the surface current. Stated in general terms, the sub-surface current at any depth is found by first establishing, by observation, its relationship to the surface current, when, the latter having been ascertained directly by observation, the former may be de- duced. The observations for sub-surface currents are executed in the same way as those for surface current, excepting that the lower can is sunk to the depth of the stratum the flow of which it is desired to know, and that the time during which the connected cans are allowed to drift is generally increased to some multiple of thirty seconds, requiring a corresponding division of the reading of the graduated line. This increase of the time interval is also sometimes necessary in the observation of surface currents when there is a low velocity. While the lower can of a sub-surface set is sinking it may be succes- sively, under the influence of several currents, setting in different directions, in which case the upper can, when set afloat and released from restraint, will sometimes not attain a steady movement until some yards removed from the station point. In most instances, however, particularly when the lower can is not sunk to any great depth, it will be found in practice that the movement of the cans is so slow that the station point may be accepted as the point of departure of the upper can in taking up the true or resultant movement, and consequently the point from which to reckon the compass bearing and the reading of the graduated line. Case I is when the station point may be taken as the point of departure. It is assumed that the connecting wire of the sub-surface set of cans is rigid and vertical, and that it has no effect on the movement of the cans. The direction of the movement of the upper can is obtained by a compass bear- ing from the boat, and this, with the reading of the graduated line, is accepted as giving the resultant of the movements of the upper and lower strata, the latter at the depth to which the lower can is sunk. 128 DEEP-SEA SOUNDING AND DEEDGING. Let 'V =. velocity of the surface current = the velocity which the upper can would have if moving alone ; i'^ =z velocity of the sub-surface currents the velocity which the lower can would have if moving alone in a horizontal plane; V = resultant velocity of the upper and lower currents zz the ve- locity of the connected cans ; a = angle included between the directions of v and V ; a^ — angle included between the directions of v^ and V ; <9=_angle included between the directions of v and i'\ V and V are given by the readings of the graduated line ; a is given by the difference between the compass bearings taken at the surface and sub-surface observations respectively. Since Oz:za-{-a}, if a^ is found we readily get 9. If V and v^ are in the same vertical plane, Y =zh {v-\-v^). If v and v^ are not in the same vertical plane, V zr the half-sum of the projections of v and v^ on the vertical plane containing V, or = the sum of the projections of ^ v and J v^ on that plane, and the solution may be effected " by constructing the parallelogram of velocities. The method of solution by projection admits of greater accuracy than the means employed in observing, and this method practiced on board the " Blake." In Fig. 1 make AB = iw, ADrrV and B A D = a. Completing the parallelogram A, B, C, D, we get the side A Cr= i i;\ and the angle BAG Fig. 2. = 9; or, in Fig. 2, since the diagonals of a parallelogram mu- tually bisect, make AB='y,AE = V, and BAE = a. Draw B E and produce it to C, making E G = B E. Then A G^r-y' and B AC = 9. SPECIMENS, DENSITIES, TEMPERATURES, AND CURRENTS. 129 If it be intended to effect a solution by computation, A B = i y and A D = V (Fig. 1) may be referred to rectangular axes and the usual formulae employed, or the solution may be obtained from the two equal triangles of the parallelogram; since B D = A C = ? w\ and BDA:=CAD^«\ we have given, in the triangle A B D, the two sides A B and A D, and the included angle B A D, to find the side B D and the angle B D A. Case II. — When, at the observation for sub-surface current^ the station point may not be accepted as the point of departure of the upper can in taking up its true movement, a modification of the method described under Case I becomes necessary. The stray-line is dispensed with, and the can is secured to the graduated line at the initial point, the white rag. When the upper can, after having been set adrift, has attained a steady movement, time is noted, and a simultaneous compass bearing of the can and reading of the graduated line are taken at the station point. When the movement has continued for thirty seconds — or some multiple of thirty seconds — a bearing and a reading are again taken. These give the data for finding V and a. In the triangle ABC, Fig. 3, let A be the station point, B the position of the upper can at the first reading of the graduated line, and C its posi- " tion at the second reading; then, from the ^ I'ig.J readings and the bearings, we have the two sides A B and A G, and the included angle B A C, from which we may find the side B C = V, and also the angle A B C, or the angle A C B, either of which, by its relation to one of the two compass bearings already taken, will give the compass direction of V. Having Y and its compass direction, the compass direction and extent of V being known from observation, we readily get a, whence v^ and the angle 6 (Fig. I) may be found as in Case I. casB III. — The observations for surface current are made from a boat at anchor, as in Cases I and II, but those for sub-surface current are made as follows : Having ascertained the surface current and lowered the sub-surface set of cans, the latter are released without any graduated line attached. At the same time the boat is cast off from the sounding-rope and her course 130 DEEP-SEA SOUNDING AND DREDGING. laid in the line of movement of the floating can, near which object her head is constantly kept, care being taken that the manoeuvring of the boat may not influence the motion of the can. Everything being ready, the set of cans used for the surface observation — with the graduated line attached, but without stray-line — is placed overboard as close as possible to the floating can of the sub-surface set and is quickly released, time being noted. The graduated line is payed out as necessary, and the boat constantly kept in her position near the floating can of the sub-surface set, as before. If there is any difference in the direction or velocity of the flow of the upper and lower strata the two sets of cans separate. At the end of the selected time interval the distance separating the two floating cans is measured by means of the graduated line, and a compass bearing of one can from the other can is taken at the station point, in the bow of the boat. This measurement gives in the triangle ABE, Fig. 2, the side B E; the compass bearing, together with the compass bearing taken at the obser- vation for surface current, gives the angle ABE. The side A B = i; being known, we have, in the two sides and the included angle cited, the data for finding the side A E = V, and the angle B A E = a. With V and a known, -u^ and 6 may be found as in Case I. When there is a swift surface current it would perhaps be easier to keep the boat near the floating can of the surface set, in which case the graduated line would have to be attached to the other floating can, but in the method as stated the boat's head at the time of getting over the second set of cans has already been laid in the direction of the movement attained by the sub-surface cans; hence, to follow the other set would often require an abrupt change of course and no inconsiderable manoeuvring. The difficulties in the way of accurate observation from a boat are evident to the nautical person. The boat is generally restless, and, when anchored to a long riding-scope at short stay, is liable to provide only a shifting station point. A bucket towed astern may lessen the swinging of the boat, but her instability cannot be overcome. The sinking and deflec- tion of the graduated line, and the oscillations of the compass-card, are obstacles in the way of trustworthy observations. SPECIMENS, DEIs^SITIES, TEMPERATUEES, AND CUERENTS. 131 REMARKS ON THE CONDITIONS ATTENDING DEEP-SEA WORK. The conditions attending deep-sea work should be borne in mind in devising apparatus intended for the prosecution of such work. This as a fact seems to be self-evident, but in the observance it is not always fulfilled, as many of the deep-sea appliances which have been devised from time to time bear evidence. Some of these conditions are stated as a reminder to those who have had no actual experience in the work. Rolling ana jpitehing of the Fessei.— Thls Is au important matter to be considered, as has been made to appear many times in this book. drifting of the ¥e»sei.— Under the iuflueuce of wind or current, or both, a vessel will drift away from the position which she occupied at the begin- ning of an operation. That there are sometimes sub-surface currents to be encountered, and that they are frequently found to move in a different vertical plane from that in which the surface current moves, must also be considered. Corrosive Action of Sea-water on Metals. — By COrrOSive actlOU, if the metal employed in the construction of apparatus used for submarine work be not properly chosen, the friction of working parts may be much increased, con- tact of valves with their seats may be destroyed, and parts not accessible for cleaning may become much fouled. specifte Gravity of Sea-water.— It must be remembered that in sea-water bodies are more buoyant than in fresh water. Thermal j9ij(ferenccs.— lustruments lu leavlug the vessel and descending to deep water may be exposed to a wide range of temperature, often from over 100° in the sunshine to nearly 32° in the deep water. In this connec- tion it should be remembered that different metals or materials expand or contract unequally under the influence of heat or cold. In delicately- adjusted parts unforeseen contact or breaking of contact may result from much change of temperature. Since the lubricating oils do not retain their fluidity at a low tempera- ture, they should not be used to lubricate parts of instruments which are to be submerged in cold water. The water acts as a lubricant. Bydrosfatic Pressure. — The pressure ou any plane surface immersed in a fluid is equal to the weight of a column of the fluid whose height is equal to 132 DEEP-SEA SOUNDING AND DREDGING. the perpendicular depth of the center of gravity of the surface, and whose base is equal to the surface pressed. Taking the specific gravity of sea-water as 1.026, the weight of a cubic inch would be .594 ounce avoirdupois. The weight of a column having a height of one fathom (seventy-two inches) and a base of one square inch would be 42.768 ounces, whence we would get the following approximate pressures on the square inch : Pounds. At a depth of 1 fathom 2.674 At a depth of 10 fathoms 26.740 At a depth of 100 fathoms 267.400 At a depth of 1,000 fathoms 2,674.000 Few valves will resist or retain the pressure in very deep water, and hermetically-closed chambers must be strong not to be collapsed. Material which was buoyant at the surface may become water-logged, or materials may be compressed until they lose their former shape. While many other points should be considered, according to the char- acter of the work or the machinery, the foregoing are some of those which are most prominent in importance because of their bearing on ordinary operations, STRENGTH OF SPRINGS. One of my chief troubles at the outset of our deep-sea work was in getting any information concerning springs for mechanical uses ; even the workmen who made springs apparently knew little more concerning them than was to be obtained by experiment in each individual case. The use of springs for delicate mechanical operations at sea should be avoided as much as possible, particularly if the instrument with which they are employed is intended to be submerged, for the springs will then undergo considerable change of temperature and sometimes much rough usage. The action of springs in air certainly does not furnish a true measure of that which they have in mud. If a flat or sheet spring be used, its broad surface, or the surface which is at right angles to the plane of flexure, should not be presented to the resistance of the water in its movement through it, unless the effect of such resistance on the flexure of the spring be taken into account. SPECIMENS, DENSITIES, TEMPERATURES, AND CURRENTS. 133 The following is copied from Principles of Mechanics, by W. J. Miller, C. E., London, 1874; E. & F. N. Spon : "A spring being a bar of metal in a coiled form, when weights are applied either to compress or extend the coil, we have a corresponding compression or extension of the metal, and, tlierefore, this change of figure will be directly as the weight or force W applied, and directly as the number of cdils. Let N = ninnber of coils, D = mean diameter of coil, and rf = side of wirr if s,|uaiv .-nKl dinnirtci- if round (idiind stc..] is usually preferred by engineers, as the square form is apt to n-M-k at fli li^vs ilmini;- .■(.ilin-) ; then cloiiL'atidu or c()ui])ression = W X N. If we now vary the diameter, and consider similar parts of such ditfcrcnt sized coils as beams undergoing bending, we may apply the formula for the deflection of beams already given. We shall thus have tlie elonga- tion or compression directly as W X N X D^. "Again, if tlie section of metal be varied, and if we still consider part of the spring as a beam, we have the deflection or change of curve as bXcP (6 = breadth), or, in this case, since b = d, as rf^ and, therefore, the elongation or compression of the coil will be inversel^v as d'', and the formula will, tlierefore, be — Elongation or compres C ^ a constant determined by experiment. "If the diameter and thickness of wire be expressed in inches and the weight in pounds, ther from experiment that for steel springs of square section — C= 1 • 2,200,000' ^ — 1,470,000 the elongation or compression being obtained in inches," CHAPTER V AND APPENDIX. DKEDGING AND TRAWLING; APPARATUS AND METHODS. FITTING THE " BLAKE " FOR DREDGING. On the arrival of the " Blake " at New York, in July, 1877, following the close of a winter season in the Gulf of Mexico, it was announced by the Superintendent of the Coast and Geodetic Survey that a part of the winter season of 1877-78, in the Gulf, would be given up to dredging, for which purpose Prof. Alexander Agassiz would be associated with the Coast Survey party. Professor Agassiz had recommended the use of steel-wire rope for dredging, and his recommendation had been approved by the Superintendent. The " Blake's " party organizatioh for the purposes of deep-sea work had existed for five years continuously : two years under the command of Commander J. A. Howell, U. S. N., and three years under my command. Since under the liberal control of the Superintendent, the arrangements of the vessel for the work in which she was engaged had been made very complete, and the party on board had become experienced in the conduct of most deep-sea operations, opportunity was offered for undertaking dredg- ing at much less trouble and expense than would have been possible with a new organization. There was needed for the dredging operations the direction of a capable naturalist, which was secured to the full in the serv- ices of Professor Agassiz ; but, for the vessel, only such additional appa- ratus was necessary as belonged strictly to a dredging outfit. The adoption of steel-wire rope, although presenting to our minds at the outset a few difficulties, which we confidently expected to overcome after a short experience, simplified matters as compared with what had previously been thought proper in a dredging outfit. Before that time Plate 24. u. s. coast survey. deep-sea sounding and dredginc. THE "BLAKE" AT THE WASHINGTON NAVY YARD. THE DREDGING GEAR READY FOR WORK. Heliotype Printing Co., 220 Devotishire St., Boston DREDGING AND TRAWLING— APPAEATUS AND METHODS. 135 dredge-ropes had been of hemp or manila, and usually, for deep work, a tapering rope of three inches, two and a half inches, and two inches in circumference had been employed. The size of the steel rope selected for our work was one and one-eighth inches in circumference throughout its whole length. ^7Wv^ G. — COMPAKATIVE Professor Agassiz and his indefatigable associate, Mr. S. W. Garman, did everything pertaining to their own special work as naturalists, and in addition accepted a share in fitting the vessel. In the division of work agreed upon. Professor Agassiz provided the dredges, trawls, tow-nets, &c., while the Coast Survey party planned and placed on board the means for working the wire rope. In its several stages of progress the preparation of the vessel was reported to the Superintendent for sanction or improve- ment, and as a rule our plans were also submitted by me to the valuable criticism and suggestions of Professor Agassiz. The dredging cruise of the ensuing season (1877-78) having proved successful, and having demonstrated the efficacy of the steel rope so opportunely recommended by Professor Agassiz, the vessel was refitted to continue the dredging work on a second cruise during part of another winter season (1878-79). Improvements were made in dredges and trawls during the first cruise, and a practical experience gained which suggested improvement or modi- fication in the method of operating the wire rope. On the completion of the second fitting of the vessel for a dredging cruise and the regular party work to follow. Commander John R. Bartlett, U. S. N., succeeded to the command. For this second preparation, the duties were divided between the naturalists and the Coast Survey party precisely as before, Professor Agassiz adding to his own special duties as naturalist the supervision of the manufacture of trawls and dredges, this time after the improved forms, 136 DEEP-SEA SOUNDING AND DEEDGING. and the party on board, under the control of the Superintendent, devising, purchasing, and putting in place the system of machinery necessary for conducting the work. In the operations at sea, the management of the vessel and of the machinery was in charge of the Naval Assistants, but no dredging was undertaken excepting in localities indicated by Professor Agassiz, he being the recognized director of the dredging operations. Although a division of duties was necessary, no stiff lines were drawn, but all exercised a common interest in the conduct of the work and in the improvement of details. When the work of each dredging cruise had been completed, and the naturalists had left the vessel, the regular work of the party, consisting of observations for depths, serial temperatures, currents, densities, &c., was resumed in charge of the naval officers, this work in each case occupying several months after the close of the dredging operations. In the course of the present chapter the methods of each dredging cruise will first be explained, and this will be followed by detailed descriptions of apparatus as finally approved and adopted. There will also be given in the appendix to this chapter descriptions of a few of the appliances used by the United States Commission of Fish and Fisheries. The appendix was written by Prof. A. E. Verrill, and I am enabled to publish it through the good offices of Prof. Spencer F. Baird, United States Commissioner of Fish and Fisheries. In selecting from the material placed at my disposal by Professors Baird and Verrill, only those things have been chosen which, as it seemed to me, might in one way or another have proved a desirable sup- plement to the outfit of the " Blake." It is not thought consistent to depart so widely from the title of this book as to include all the valuable appli- ances of the Commission. In letters to the Superintendent of the Coast and Geodetic Survey, which have been published as Bulletins of the Museum of Comparative Zoology at Harvard College, Cambridge, Mass., Professor Agassiz has set forth the valuable results obtained in his department of science by the dredging cruises of the ''Blake." The heliotype views show the vessel prepared for the second dredging cruise, excepting that in some of them the experimental Sigsbee sounding- DKEDGING AND TRAWLING— APPARATUS AND METHODS. 137 machine — which soon after these views were taken was rephice(t by the later form of the same machine (Plate 8) — is still in position. THE FIRST DREDGING GRUISE. (Figs. 1 and 2, Plate 29.) AppatatuH ami Methods. — III preparing the vessel for this crnise it was agreed, owing to the somewhat experimental nature of the work and the short time allotted for its execution, that the expenses should be restricted to the lowest figure; consequently the main hoisting-engine, although of doubtful power for very deep work, was fitted with a winch-head and con- tinued in use. The trouble to i^e feared with the steel rope was kinking, but from motives of economy a considerable risk was knowingly taken in this respeci. in adopting the plan by which we first worked the dredge-rope. There were provided but two lengths of the steel dredge-rope, each being 3,000 fathoms. One length was kept on a large iron reel, B, which was mounted on standards and controlled by a friction-brake. The reel was the same that is shown on several of the plates, but on this cruise it was operated by hand-cranks, and the friction-lever was on the after side. A swinging-boom, D, provided with topping-lift and guys, was mounted on the foremast by means of a band and goose-neck. At the outer end of the boom was a large iron snatch-block, G, hooked to a pendant that connected with an accumulator or dynamometer. The pendant' rove through a small iron leading-block of extra strength permanently secured at the boom end; thence over a sheave in the heel of the boom, whence it was made fast to the accumulator, the latter at the outset being laid on the upper side of the boom, and afterwards, as being more favorable to its proper action, sus- pended from the mast-head. The positions of the several independent parts of the dredging apparatus are very well indicated by the plans on Plate 29 and by the heliotype views. In paying out (Fig. 1), the dredge-rope passed directly from the reel through the pendant-block, under frictional control at the reel. For hauling back (Fig. 2), it was tirst stoppered abreast the pilot-house k, then slacked at the reel and led through a second large iron snatch-block, C, forward of the reel and abreast the winch-head of the hoisting-engine. With the bight of 18 D s 138 DEEP-SEA SOUNDING AND DEEDGING- rope formed between the deck-block and the reel eight or nine turns were taken around the winch-head of the engine. This operation completed, the cranks of the reel were manned, the strain on the rope taken up by the engine, stoppers ''come up," and the rope brought in at a rate varying from one minute to six or seven minutes per one hundred fathoms, according to circumstances. As the rope, while coming in, passed off the winch-head it was wound " hand taut " upon the reel. For the purposes of winding and guiding, a guy-rope was used, one end of which was made fast to the vessel's rail, the other end being turned over an iron thimble through which the dredge-rope was always kept rove. For stoppers, several long lengths of sennit were used. The sta- tions of men are shown by crosses on the plate. The objectionable feature of this method of winding the wire rope was in taking turns around the winch-head "07i the bight,'' which, by twisting the rope, pro- moted kinking. Watchfulness and care were necessary, but exercising these we were able to avoid kinks, excepting at the outer one or two hundred fathoms, where a kink was perhaps an advantage rather than a drawback. Kinks were easily straightened out, but they left the rope less strong than before. At our first attempt with the dredge we were brought to grief by an indescribable tangle of the outer two hundred fathoms of the dredge-rope, which happened in this wise: The rope had been payed out rapidly, the vessel backing slowly meanwhile and drawing the rope ahead; the large, insufficiently-weighted dredge having met with more resistance than the compact and heavy steel rope, the bight of the latter had landed first, and the outer two hundred fathoms of the rope, still descending, had gone down upon its own parts in confused coils. This we afterwards came to consider a most fortunate and timely acci- dent, for, it having taught us how to lower the dredge, we did not again meet with a like trouble during the whole progress of the work. There- after the dredge, more heavily weighted, was lowered with the submerged rope kept vertical and under strong tension until the bottom had been approached to about fifty fathoms, when the rate of paying out was dimin- ished and the vessel slowly backed until the dredge took ground, after DEEP- SEA SOUNDING AND DREDGING. \l S COAST S URVE Y. FjGIPLAN of trawl as FTKS'I' VSl'l' ON BOAT-li! TME ■BLAKE'.' FIG.2.PLAK OF TRAWL AS l-MPROVED BY PROFESSOR ACASSIZ. LJFU'I'. COMDR. SXGSBE.E AND ITEUT . DREDGING AND TRAWLING— APPARATUS AND METHODS. 139 Avhich the rate of paying out was increased and the vessel backed accord- ing to circumstances, the rope always heing kept well taut. The extent to which the boom was topped up for work is shown on Pkites 24 and 30. A sounding, and an observation for bottom tempera- ture, preceded the dredging operations at each station occupied. For lowering the trawl, with its heavy iron frame and long, pendent bag, a different method was adopted, as suggested by consideration of the unequal resistances encountered by the parts mentioned in passing through the water, it being necessary to guard against the bag getting up over the frame-work. With the end of the bag well weighted, the trawl w^as payed out cautiously, the vessel backing slowly to keep the rope tending slightly ahead. As the trawl neared bottom the reel was stopped for several minutes, while the backing of the vessel was con- tinued. Then the w^ork of paying out was resumed until the trawl had landed. Our method in this respect increased the probability of plant- ing the trawl fairly on its runners and of keeping the rope taut at a critical moment. The steel dredge-rope when held in the hand always gave the most decided indications of the 'dragging of a dredge or trawl along the bottom, and as soon as the implement was felt to be "biting" the additional scope of dredge-rope thought necessary was payed out as desired by backing the vessel and regulating the friction at the reel. No weights were used on the steel rope in advance of the dredge or trawl, as is necessary when the rope employed is of hemp or manila. The weight of the steel rope alone was found to keep the implement flat. The length of rope payed out, whether for dredging or trawling, gen- erally followed this rule: In depths no greater than three hundred and fifty fathoms, equal to twice the depth of water; in depths exceeding that, one-third greater than the depth of w^ater. A tackle from the forward .part of the swinging-boom was used for hoisting the dredge and its contents over the rail to the deck, but the trawl, being unwieldy, was first swung abreast of the fore rigging by means of a mast-head tackle, from which position it was hoisted until the frame had cleared the vessel's rail, when the netting was gathered aboard by hand. 140 DEEP-SEA SOUNDING AND DEEDGING. Professor Agassiz suggests the use of a light gaff on the forward part of the foremast for this purpose. It has been stated that the dredge and the trawl were improved during the first dredging cruise; in what respect will now be shown. Those with which we fitted out are illustrated in Fig. 1, Plate 25, and Fig. 1, Plate 26, respectively. Early in our work it was noticed that the dredge gave but few specimens of animal forms from soft bottoms, even when it came up filled with the bottom material. This material being ordinarily of a moderately tenacious character, requiring a long-continued manipulation to force a quantity of it through a sieve in water, it was supposed that the dredge on reaching bottom soon became surcharged with the mud or ooze, and that very little washing out through the netting taking place thereafter, other matter was excluded after the first few feet had been traversed. Additional evidence on this point was afforded by the profusion of specimens brought up on the tangles from the same localities, and also by the disproportion- ately greater number obtained in the trawl as compared with the dredge. The opinion was broached early in the work that the dredge should skim the ground rather than plow into it, and in its form should partake of the char- acteristics of both the dredge and the trawl. Although this view was op- posed to previous practice. Professor Agassiz thought it worth submitting to experiment. Accordingly, Master H. M. Jacoby and the writer improvised a dredge which would not plow, and it proved so successful at the first ven- ture that afterwards, at Key West, a drawing was prepared from which an improved dredge, as shown in Figs. 2, 3, and 4, Plate 25, was constructed. The new dredge was used thereafter with much better results than we had met with in the use of the old dredge. With the former more than thirty hauls were made, some of them oh very soft bottom, but in only two or three instances did it bring up more than several handfuls of mud or ooze, although by lining the bottom of the bag with closely-woven stuff, bottom material in considerable quantity might nearly always have been obtained. It is evident that the improved dredge, without the special lining, collects the material of soft bottoms in such small quantities that the much-desired washing through the netting of this material in the process of dragging actually takes place. PLATE 27. U. S. COAST SURVEY. DEEP-SEA SOUNDING AND DREDGING. THE IMPROVED TRAWL READY FOR USE. SEE FIGURE 2, PLATE 2 Heliotype Printing Co., 220 Devonshire St.. Boston. DEEDGING AND TRAWLING— APPARATUS AND METHODS. 1.41 With the style of trawl that had previously been used for deep-sea work it was essential to success that it should land fairly on its runners ; that is, with the beam uppermost. Although it would land as desired in most cases, yet experience had shown repeated failures, and a failure in deep water involved the loss of much time and the risk of valuable gear without compensation. Professor Agassiz, Lieutenant Ackley, and the writer, in the course of a conversation, each offered suggestions until we had succeeded in draw- ing up a rough design for the trawl shown in Fig. 2, Plate 26, and also on Plates 27 and 28, and we afterwards had much reason to be gratified with the working of the improved implement. THE SECOND DREDGING CRUISE. (Fig. 3, Plate 29.) Apparatus and jiethoas. — The first dredging cruise having established beyond doubt the superiority of steel rope over hemp or manila for dredg- ing purposes, the Superintendent authorized a more complete outfit for the second cruise. Fig. 3 shows the method of working the dredge-rope during this cruise. The reel B, containing the rope, was the same that had previously been used, but it was reversed to bring the brake-lever on the forward side, and was provided with a small double-cylinder reversible steam- engine, E, for winding the wire. The lead of the rope was as follows: From the reel it followed the course of the dotted line, passing through the several iron snatch-blocks G, C, Sec, eight or ten turns being taken around the winch-head of the hoisting-engine A. This was the lead of the rope, both for paying out and for hauling back; there was no need to take turns around the winch-head "on the bight" as before, and thus the rope could be kept constantly under tension, which is almost a necessity in working wire rope. The fleet aft, from the reel B to the first block C, was a long one, rendering it easy to guide the wire evenly on the reel when hauling back. The swinging-boom and its fittings were the same as before, excepting that a new accumulator, or dynamometer. Fig. 3, Plate 34, was provided. The new hoisting-engine A was very different from that for- merly used. On the latter the winch-head was permanently connected with 142 DEEP-SEA SOUNDING AND DEEDGING. the crank-shaft by gearing, and could not be worked independently of the engine. The new engine (Plate 33) will be more fully described hereafter, but it is necessary to give some idea of it at this point in order to explain clearly the operation of dredging during the second cruise. The winch-head, which over its smallest circumference exactly accom- modated one fathom of the rope in a single turn, was fitted with a friction- band, the lever for which could be instantly locked in position, either when the friction-band was out of contact or when binding with full force. By means of a clutch and lever, the latter fitted to lock in position, the winch- head could be connected or disconnected from the engine at will. A worm on the hub of the winch-head was made to engage the gears of a counter or register such as was used on the sounding-machine. By this means, due to a timely suggestion by Lieut. W. 0. Sharrer, it was no longer necessary to mark the dredge-rope; the counter gave the length of rope out with a percentage of error too small to be of consequence in dredging, for the exact depth was always first ascertained with the sounding-machine. All appliances for controlling the engine were placed on the starboard side, and one man standing on that side, as shown by the cross on Fig. 3, per- formed five duties — viz, to attend the throttle, the friction-lever, the clutch- lever, the reversing-lever, and to read the counter. At the dredge-reel the arrangement was similar; the man standing at. that point attended the throttle, the friction-lever, the clutch-lever, and the reversing-lever. In addition, he could guide the rope on the reel in case of emergency. The drawings for the hoisting-engine were made by Mr. Earle C. Bacon, of Messrs. Copeland & Bacon, 85 Liberty street, New York. I stated to him the size of cylinders, relation of gears, the action required of the several parts, the positions of levers and throttle — in general terms the requirements; and he then worked the whole out in his own way — no easy matter, as may easily be seen — using his patent trunk-cylinders ; and so successful was he in the design that not a single fault has been found with his engine by those who have used it. He worked out the form of the winding-engine at the reel, and with the same success. U. S. COAST SURVEY. PLATE 28. DEEP-SEA SOUNDING AND DREDGING. THE IMPROVED TRAWL SHOWN AS HAVING "TRIPPED" AFTER FOULING WITH ROUGH BOTTOM. Heliotype Printing Co., 220 Devonshire St., Boston DREDGING AND TRAWLING— APPARATUS AND METHODS. 143 On this cruise the methods adopted for planting the dredge and trawl were practically the same as on the previous cruise, but as regards the working of the machinery and gear Professor Agassiz and Commander Bartlett state that the drawbacks which had been experienced before were not met with at all. The work proceeded smoothly, and without accident which could in any way be laid to the agency of the machinery. The rope could be wound upon the reel wath nice regularity. The operation of paying out rope was managed as follows : the dredge or trawl being shackled to the rope and over the side, the counter set, the friction-brake at the reel in hand, and the engine at the reel out of gear, the brake at the hoisting-engine was thrown out of action and locked; the winch-head was clutched to the gears and the link adjusted for reversing the engine. In this state everything was ready. The weight of the dredge or trawl alone not being sufficient to overcome the various resistances opposing the movement of the rope, it was necessary to pay out with the hoisting-engine until the weight of several hundred fathoms of rope had been added thereto. All that was required to start the operation, after the preparatory measures already described, was to open the throttle. When the submerged weights were sufficiently heavy to overhaul the rope, the throttle was closed and the winch-head unclutched from the gears. The friction-brake at the reel needed careful attention, particularly when the hoisting-engine was turning over, for the latter was powerful enough to part the rope, while the former could give a resistance much beyond the breaking strain of the rope. In dragging, the strain was taken at the winch-head, controlled by the brake, backed, if necessary, by the brake at the reel. For hauling back, the winch-head and the reel were thrown into gear with their respective engines, and the links of each engine adjusted for winding up the rope. The brake at the reel was secured out of action, and the throttle of the winding-engine was then opened slightly. As nearly as possible at the same time steam was turned on at the hoisting-engine and the brake on the winch-head locked out of action. Afterwards the speed of the winding-engine was regulated to suit that of the hoisting-engine, the object being to keep the rope taut between the two engines in order to 144 DEEP-SEA SOUNDING AND DEEDGING. avoid kinking, and at the same time not to wind it upon the reel under so severe a tension as to accumulate a great crushing force upon the drum or barrel of the reel. After our first dredging cruise it was the general opinion on board that, in dredging, an accumulator was not a necessity, excepting as a dynamometer and to give a slight elastic cushioning. A critical moment in dredging is when a dredge or trawl which has fouled with the bottom is in the usual position for breaking ground — that is, when the rope is vertical and under great strain. At such a time it is desirable to know the condition of affairs below, and this a dynamometer will show, although after a short experience a person can form a correct judgment by holding the rope in his hand. When the dredge is foul, it must generally be broken adrift by strain, not by cushioning. Sometimes, however, a little man- oeuvring of the vessel over the rope may serve to clear a foul, and then cushioning is desirable. When dragging, the change in form of the catenary of the rope gives the effect of an accumulator. The "Blake's'' accumulator was capable of extending about six feet, and this was found to give ample cushioning. The deepest haul made by the vessel was in 2,400 fathoms. During this dredging cruise the trawl was still further improved in a manner which will be explained in its proper place. On the first dredging cruise tow-nets had been used only at or near the surface, because Professor Agassiz had but little confidence in the value of the tow-net as it had generally been worked in deep waters — i. e., with the mouth wide open during the several processes of lowering, dragging, and hauling back. The exact habitat of specimens brought to the surface in this way was thought to be very much in doubt. The desirability of having a tow-net which could be kept closed in lowering and hauling back, and yet be kept open when dragging, was several times the subject of con- versation on board. I suggested something of this kind: the net to be fastened to the dredge-rope and lowered with the mouth closed; when dragging, a weight to be sent down on the rope, which would open the tow- net and at the same time detach itself and fall clear; when ready to haul back, a second weight to be sent down to close the mouth of the net. This DEEP- SEA SOUNDING AND DREDGING. U. S COAST SURVEY. Pl.ATF, PLANS OF THE DECK AND APPARATUS OE THE "BLAK-E I' FIG'S.l ,^2. DURING THE FIRST DREDGING EXPEDITION. F1G.3. DURING THE SECOND DREDGING EXPEDITION. DREDGING AND TE A WLING— APPARATUS AND METHODS. 145 is a vague suggestion, but it might perhaps be put in mechanical shape.* On the second dredging cruise an open-mouth tow-net was tried in deep water, but not with much success in getthig specimens. Another device, called the tangle-bar drag, for dragging along the bottom, was used on the second cruise. It was towed by a bridle, and had sAvabs secured along its whole length. This apparatus brought up specimens in great profusion. GENERAL REMARKS. The advantages gained by the use of wire rope for dredging purposes are chiefly in the following particulars: compactness, strength, durability, neatness, facility of handling with a small force, celerity of operations, and economy. The duration of the dragging-interval was made much shorter in the . "Blake's" work than had previously been the practice. In the greater depths, where more time was consumed in lowering and hauling back, a longer interval was usually allowed than in depths less than five hundred fathoms. This restriction of the dragging-interval was perhaps a natural consequence of the increased facilities gained in dredging with wire rope, but it seems a reasonable way of working from other points of view. A first haul will generally indicate, to some extent, the fertility in specimens of the bottom that is being worked, whence barren ground may be abandoned or rich ground worked exhaustively. The longer the dredge or trawl is * An apparatus for this purpose, which has recently beau devised by the writer, at the request and with the assistance of Professor Agassiz, has now been made by authority from the Superintendent of the Coast and Geodetic Survey. It will be tested during the coming summer, aud doubtless will be published afterwards, with such improvements as experience may suggest to Professor Agassiz, under whose direction it will be used Our plan is to trap the specimens by giving to a cylinder, covered with gauze at the upper end and having a Hap valve at the lower end, a rapid vertical descent between any two depths, as may be desired; the valve during such descent to keep open, but to remain closed during the processes of lowering and hauling back with the rope. Au idea of what it is intended to effect may be stated briefly thus: Specimens are to be obtained between the intermediate depths a and h, the former being the uppermost. With the apparatus in position, there is at a the cylinder suspended from a friction clamp in such a way that the weight of the cylinder and its frame keeps the valve closed ; at h there is a friction buffer. Everything being ready, a small weight or messenger is sent down, which on striking the clamp disengages the latter and also the cylinder, wliin messenger, clamp, and cylinder descend by their own weight to h with the valve open during the passnge. W'lien the cylinder- frame strikes the buffer at 6 the valve is thereupon closed, and it is kept closed thereafter liy the ^veight of the messenger, clamp, and cylinder. The friction bufl'er, which is four inches long, may be I'eguUited on board to give as many feet of cushioning as desired. All parts are simple and strong. The size of the cylinder for trial is : height, two feet ; diameter, ten inches. April, 1880. 19 DS 146 DEEP-SEA SOUNDING AND DEEDGING. dragged the greater the probability of fouling and losing the implement and its contents, although the probability of fouling in very deep water is generally not so great as in the lesser depths. Professor Agassiz found that some of the more delicate specimens were much injured when a long dragging-period had been allowed. On the first dredging cruise, with the imperfect machinery then on board, we would haul as many as eight times in one day in depths varying from one hundred fathoms to 1,500 fathoms. On one occasion we made a fine haul at eight hundred fathoms in one hour and twenty minutes, including twenty-three minutes for dragging. The time was taken on letting go and again when the dredge or trawl appeared above water. After the departure of Professor Agassiz from the vessel, shortly before the expiration of the first dredging cruise, we made in one day, between 7 a. m. and 5 p. m., ten hauls with the dredge off Havana in depths from fifty to four hundred fathoms. The bottom was rough and the dredge fouled at every haul, but no losses occurred, and the hauls were rich. Throughout the second cruise the work seems to have been done intentionally somewhat slower than before, but at the same time with greater steadiness. The following may be set down for safe work : Time per one hundred fathoms paying out and hauling back, three to five minutes, according to circumstances ; time for dragging, ten to thirty minutes, according to depth and the character of the bottom. The rate of dragging may be from one and a half to three miles per hour, according to the character of the bot- tom and the state of the sea. Paying out, and also hauling back after the dredge or trawl is off bottom, is so easily done that there is a great tempta- tion to work rapidly, but it should be remembered that in paying out it is of the first importance to plant the implement properly on the bottom, and that in hapling back the delicate specimens may be injured by too great speed. dredges: the old pattern and the improved pattern. (Plate 25.) The objection to the old dredge for general use has already been stated, but as it has hitherto been regarded almost as a standard form, DEEDGING AND TRAWLING— APPAEATUS AND METHODS. 147 and in special cases would be more serviceable than that which is herein styled the improved dredge, a description of it is given. . The oia-pattern Dreage ( Fig. 1 ) . — There is a frame consisting of two flaring mouth-pieces of flat wrought-iron, beveled on their front edges, perforated with a row of holes along their rear edges, and joined to each other at their ends by bent wrought-iron braces. The braces serve also to hold the two wrought-iron arms forming the span or bridle by which the dredge is attached to the dredge-rope. A band of netting is stitched along one of its edges to the frame by means of plia- ble wire passed through the holes already mentioned; the free edge of the band is then gathered and seized so as to complete an open-mouth bag. Two lengths of stiff cotton canvas stitched to the frame over the netting form a shield for the latter when the dredge is dragging. The rear edges of the lengths of canvas and the bottom-seizing of the netting bag are stopped to a wisp of ratans, which serves also for fastening on sink- ing weights and swabs or tangles. One arm of the dredge is longer than its fellow, and to the eye of the long arm the dredge-rope is shackled. The eye of the short arm is seized with five or six turns of rope-yarn to the eye of the long arm. In the event of a foul on rough bottom endan- gering the dredge-rope, the rope-yarn seizing will part and allow the dredge to slew, an action which rarely fails to disengage it from an obstruction. These dredges are of different sizes, the frame of that for general use being about three feet wide, eight inches deep in the throat, and its length to the end of the bag being about four feet. The iniprovea jtreage (Figs. 2, 3, aud 4) . — By reasou of having flaring mouth-pieces,, and a flexible body composed of the bag and shield, the old- pattern dredge is almost sure to plow deeply into yielding bottoms. Since the object sought in the fashioning of the new dredge was to effect a skim- ming of the bottom rather than a deep penetration therein, a very decided departure from the form of the old dredge was necessary. The frame of the new dredge is a rectangular skeleton box made of wrought-iron. The mouth-pieces are flat, beveled on the forward inner edges, perforated along the rear edges as on the old dredge, and are riveted to the skeleton or bar-iron portions of the frame-work, in which position 148 DEEP-SEA SOUNDma AKD DEEDGING. they are held parallel. The rear of the upper and lower sides of the skele- ton are connected by three riveted braces, the whole frame-work being- rigid. A tangle-bar of wood, bar-iron, or iron pipe, to carry the weights and tangles, has seized to it three sister-hooks, which are hooked severally around the braces and moused. The arms are like those of the old dredge, one arm being longer than the other. A netting bag and canvas shield, as in the ease of the old dredge, are stitched with pliable wire to the dredge- frame. A trap like that of the trawl is fitted inside the main bag. The bottom of the main bag is stopped to the middle brace at the rear of the frame. Each flap of the canvas shield is turned over and around its own side and end of the skeleton frame, and stitched to its own part with stout twine, presenting a tolerably smooth sliding-surface. DIMENSIONS OF IMPROVED DBEDGE. Ft. In. Length from moutli to rear of frame 4 Depth between mouth-plates or flanges 9 Widthofframe .. a Mouth-plates: Width 4J Thickness of metal | Distance of row of holes from rear edge J Distance apart of holes 1^ Skeleton frame, diameter of round-iron ^ Longarm: Length 3 1 Diameter of round-iron f Shortarm; Length 2 11 Diameter of round- iron f Shield (cotton canvas) . . No. 3. Netting for main hag and trap: Mesh (square)., i inch. Stuff (tarred cotton) . . ^^ thread.* If it be intended to bring up a specimen of the bottom material with this dredge, the bottom of the main bag may be lined for a short distance with muslin. THE IMPROVED TRAWL. (Fig. 2, Plate 26.) The plate shows the general plan, not the details. Two wrought-iron runners are connected by two wrought-iron pipes or beams as shown, excepting that the ends of the beams fit into collars which are riveted to the runners. The several parts of the frame are rigidly * See netting for dredges and trawls, page 154. DREDGING AND TRAWLING— APPARATUS AND METHODS. 149 joined together, so that, when dragging, the runners move in parallel planes at right angles to the axes of the heams. An open-mouth netting bag, roped all round the mouth, and with the roping leaded at intervals, is laced along the rear ends of the runners and strongly secured to the corre- sponding corners. This leaves two free bights or loops of roping, one of which trails on the ground when the trawl is being dragged. The mouth of the bag should be made large enough to allow either loop that may be uppermost to hang as low as the beam when the trawl -is lying flat. This and all other netting bags described herein are made from netting pur- chased in long lengths or bolts. The main bag is formed from a rectan- gular piece of netting cut from the bolt, the raw edges being joined in a seam to run lengthwise on the bag. The lower edge of the band, opposite the moutli, is then gathered and the folds are seized together. A second but shorter bag, called a trap, is fitted neatly within the main bag at one- half or one-third the length of the main bag from the frame, forming a pocket of considerable size for the reception and retention of specimens, the only entrance or exit being through a small hole in the bottom of the trap so long as the bottom of the main bag is kept closed. The netting around this trap-hole is either roped or bound with heavy wire, the latter being preferable, as a rope grommet often twists into a "figure-of-eight" in water. From the grommet or wire hoop, as may be, several long stops are passed to the seizing at the bottom of the main bag to protect the trap against reversion. The trap may be made from a triangular piece of netting. In order to prevent the uppermost side of the main bag from falling and closing the entrance to the trap when dragging, a piece of rope some- what longer than the width of the main bag, and having corks strung upon it at intervals, is fastened by each end to the sides of the main bag, inside the latter. As thus described, and fitted with the bridle shown in Fig. 1, we have the trawl as improved on the first dredging cruise. Afterwards other improvements were adopted. . I modified the bridle, making it as shown in Fig. 2. The new bridle is secured to the runners at the front beam by lashings passed through cut-splices in the rope ; to the runners at the rear beam by lashings taken around the rope, and to the seizing at the 150 DEEP-SEA SOUNDING AND DEEDGING. end of the main bag by lashings taken through thimbles which are turned into eye-splices. The function of the new bridle is to bring up the trawl rear end foremost in the event of severe fouling on bottom, the tripping being brought about by the parting of the lashings. (Plates 27, 28.) Fouling with the trawl we found to be a very serious matter, as it was sometimes impossible to clear it when using the old style of bridle. As used on the second dredging cruise the mouth of the main bag was made larger; the roping was carried forward arid made fast to the runners at each end of the front beam, giving a longer bight of the roping to trail on the ground than before; and to prevent the uppermost bight from fall- ing and closing the entrance to the bag a rectangular piece of netting was stretched between the two beams and laced to them along their whole length. The latter contrivance is also intended to guide certain specimens into the bag. These improvements are, I believe, by Professor Agassiz and Ensign G. H. Peters. Professor Agassiz added a netting jacket inside of the main bag from the mouth of the trap downwards. The bottom of the jacket was lined with four feet of a smaller size of netting, and was closed by gathering the folds as in the case of the main bag. An idea which occurred independently to Professor Agassiz and my- self, but which was not put ih practice, was to make the mouth of the main bag larger, and to reeve the roping through bull's-eyes or thimbles at each of the rear corners of the runners. The strain on the dragging bight would then gather the slack of the uppermost bight through these fair- leaders, keeping it clear of the mouth of the bag and lengthening the drag- ging bight. It would involve some little trouble to adapt the roping to this movement in order that the netting might not be dragged through the fairleaders, and that the strain on the corners of the runners caused by the pull of the dragging bight might not be multiplied. The following sug- gestion is offered for this purpose : A rope, of the same length and size as that used for the roping, to be rove through the fairleaders and made into a band; the roping of the bag to be seized to -this band at short intervals, excepting for a certain distance near each fairleader, where it is to be left free to permit the traveling of the band through the fairleaders as required. DEEDGING AiTD TEAWLING— APPAEATUS AND METHODS. 151 By a careful arrangement of the end seizings of the series, the traveling of the band might be stopped at such a point and in such a manner as to avoid multiplying the strain at the corners of the frame. Toggles turned into the roping might also be used for the purpose. A comparison of Figs. 1 and 2, Plate 26, will show, without further explanation, the points of difference between the improved trawl and the trawl that we first used. DIMENSIONS OF STANDARD TKAWt FOR DEEP-SEA WORK, No. 1. Runners: Length 48 inches. Depth 30 inches. Width 3 inches. Thickness of metal i inch. Front pipe or beam : Length 10 feet. Outside diameter 2^g inches. Thickness of metal iV inch. Rear pipe or heam: Length 10 feet. Outside diameter 2 inches. Thickness of metal i\ inch. Collars on ends of teams : Length 2i inches. Thickness of metal } inch. Diameter of bolt f inch. Rope : For bridle (hemp or manila) . . 3 inches. For roping (hemp or manila) . . 2i inches. Main bag: Length 15 feet. Size of mesh (square).. 1 inch. Stuff (cotton).. 21 thread. Trap: Mesh (square).. i inch. Stuff. (cotton).. 15 thread. Jacket : Mesh (square) . . i inch. Stuff (cotton) . . 15 thread. Bottom lining : Mesh (square).. i inch. Stuff (cotton) . . V thread DIMENSIONS OF SMAUj BUT HEATY TRATTL FOR INSHORE WORK, No. 3. Runners : Length 30 inches. Depth 14 inches. Width 3 inches. Thickness of metal f inch. Front pipe or beam : Length 8 feet. Outside diameter 2 inches. Thickness of metal Thick. Rear pipe or beam : Length 8 feet. Outside diameter li inches. Thickness of metal Thick. Ropes and netting .' Same as for large trawl. DIMENSIONS OF LIGHT TRAAVt FOR DRAGGING RAPIDLT, No. 3. Runners: Length 1 48 inches. Depth, at rear end 24 inches, tapering forward to 18 inches. Width , 2 inches. Thickness of metal i inch. 152 DEEP-SEA SOUNDING AND DREDGING. Front pipe or beam : Length 10 feet. Outside diameter 2-^g inches. Thickness of metal ^s inch. Rear pipe or beam; Length. 10 feet. Outside diameter 2J inches. Thickness of metal -?e inch' Ropes and netting Same as for standard trawl. No. 3 trawl is recommended by Professor Agassiz for rapid dragging. He states that they get, usually, more fishes and Crustacea. In his notes, from which the tables of dimensions have been mainly compiled, I do not find the size of the beams of No. 3, so I have made them the same as those of the large trawl. The cost Oi the ''Blake's" trawl-frames was from $17 to $20 each. WEIGHTING DREDGES AND TRAWLS ; TANGLES. When fitting out for each dredging cruise we purchased a number of cast-iron twelve-pound weights, which we used as sinking-weights for dredges and trawls. Although we were plentifully supplied with sounding- shot these lighter sinkers were found to be more generally useful — permit- ting a better distribution of weights. Our custom was to load the trawl with two twelve-pound weights on each runner and a sixty -pound sounding-shot at the end of the main bag, as shown on Plate 27. It is, perhaps, better and cheaper to load the runners in this way than to make them heavier in the manufacture. In the lesser depths probably no extra weight would be needed. Another way of loading the bag of the trawl is to string two or three sounding-shot on a cheap form of sounding-rod trailing from the bottom seizing of the bag; the shot are detached on striking bottom. This insures a good descent, but is expensive. The dredge was generally weighted with three twelve-pound sinkers suspended from the tangle-bar, which was of wood. Sometimes we would also lash a twelve-pound sinker transversely on each side of the mouth. We used a wooden tangle-bar that it might break if badly jammed between rocks. Four tangles were lashed to the tangle-bar of the dredge. These were simply large swabs of hemp rope-yarns. The length of the tangles should Plate 30. U. S. COAST SURVEY. DEEP-SEA SOUNDING AND DREDGINC. VIEW OF THE ■• BLAKE'S" DECK LOOKING FORWARD FROM THE BOW OF THE STARBOARD QUARTER-BOAT. READY FOR PAYING OUT THE DREDGE. Heliotyfie Pymting Co.. 220 Devonshire St., Boston DREDGIIS^G AND TRAWLING— APPARATUS AND METBODS. 158 be less than that of the dredge, otherwise they may float over the mouth of the dredge and foul while paying out. After being picked over, the tangles often remain matted with sponges, broken spines, 6cc. The best way to clear them is by towing them overboard. THE TANGLE-BAR DRAG. The use of this implement from the "Blake" was begun on the second dredging cruise, at the instance of Professor Agassiz. A wTought-iron plate six feet long, three inches wide, and half an inch thick, Avith the forward edge beveled, had fastened to it at intervals along the rear edge a number of tangles to be dragged along the bottom. At each end and midway between on the front edge were eye-bolts for attaching the three legs of a bridle, and midway on the rear edge was another eye-bolt from which a sixty-pound sinker was dragged by a short length of rope. This drag was used with great success. I think twelve was the number of tangles attached to a single bar. TOW-NETS OR DRAG-NETS. Those used by us on the first dredging cruise were brought on board by Professor Agassiz. They were composed of a bag of embroidery canvas, Swiss muslin, or some similar stuff laced to a ring of brass wire one-fourth of an inch thick. To the ring was secured the three or four legs of a bridle to which the tow-line M^as bent. The nets may be of any dimensions desired. Ours, which were only used near the surface, were about fifteen inches across the mouth. Professor Agassiz has sent me a diagram of a large drag-net used in deep water on the second dredging cruise. In this the mouth-ring was of three-fourths-inch wTought-iron and elliptical in shape, the diameters being five feet and three feet respectively. The bag was of netting one- fourth-inch square mesh, with a lining of muslin at the bottom to form a pocket. Professor Agassiz remarks that they should be moved through the water rapidly.* * See foot-note, page 145. 154 DEEP-SEA SOUNDING AND DEEDGING. NETTING FOR DREDGES AND TRAWLS. The netting for the "Blake" was purchased from the American Net and Twine Company, 43 Commercial street, Boston. For the first cruise the main bags of trawls were regularly made in the manufacture, i. e., the round at the bottom was made by gradually decreasing the size of the meshes. For the second cruise, Professor Agassiz purchased the netting in lengths, and the bags were made on board as described heretofore. Our purchases of netting for this cruise were as follows: For main bag of trawl : web to hang ] ,000 feet by twenty feet, mesh one inch square, twenty-one-thread cotton ; seven hundred and fifty-nine pounds, at forty-five cents per pound. For trap and jacket of trawl: web to hang 1,000 feet by six feet, mesh one-half inch square, nine-thread cotton; two hundred and fourteen pounds, at seventy cents per pound. For bag and trap of dredge : web to hang sixty-seven feet by six feet, mesh one-quarter inch square, ^ tarred cotton; fourteen pounds, at two dollars and fifty cents per pound. The term '^web to hang'' means when slightly stretched, as when attached to the roping of a seine. The meshes are measured either by the diagonal or by the length of one side. Thus a mesh having each of its four sides one inch in length is called a two-inch mesh or one-inch square mesh. The latter term seems to be the plainer. Professor Agassiz recomfnends changes in the above as follows, and these changes have been introduced- into the tables of dimensions already give^i: For main bag of trawl, web to hang fifteen feet instead of twenty feet. For tra^ and jacket of trawl, fifteen-thread cotton instead of nine-thread cotton. The difference in cost and weight is as fifteen to nine. TUBS AND SIEVES. The "Blake's"" supply of these appliances was very simple: a nest of sieves, from coarse to fine, and several tubs. The tubs were of thick wood, iron' bound, and fitted with iron handles. They were about • twenty-four inches high, twenty inches in diameter at the top, and somewhat less at the bottom. We found that these answered our purpose well for deep > W GO DREDGING AND TRAWLING— APPAR AT CTS AND METHODS. 155 work, but in the work of the Fish Commission down only to a depth of two hundred fathoms, the hauls being more frequent and the specimens gen- erally less fragile, the special appliances shown in the appendix to this chapter are used with success. STEEL-WmE DREDGE-ROPE. Our rope was made at Trenton, N. J., by the John A. Roebling's Sons Company. It was one and one-eighth inches in circumference, and was composed of six strands laid around a tarred hemp heart. Each of the six strands was composed of seven galvanized steel wires of No. 19 Ameri- can gauge (No. 20 Birmingham gauge). The ultimate strength of the rope was 8,750 pounds,* weight per fathom 1.14 pounds in air, and approxi- mately one pound in sea- water; price, eight cents per foot. For the first dredging cruise it was supplied in 3,000-fathom lengths, each length wound upon a separate wooden reel. For the second cruise, the working reel already having 2,700 fathoms upon it, I had the rope supplied on wooden reels, each containing only five hundred fathoms, in which shape it was easier to handle in the event of having to replace losses at sea. One wooden axle common to all these reels formed part of the outfit. The shortest nip that we gave the rope was over the pulleys of the leading-blocks, the scores of which were eighteen inches in diameter, and this did not break up the zinc enough to give trouble from rusting. We used no preservative on the rope and had no need for it, but that recom- mended by the Roeblings is raw linseed-oil applied with the fleecy side of a piece of sheepskin, or to the oil may be added equal parts of Spanish brown or lamp-black. To preserve wire rope kept under water they recommend a mixture of mineral or vegetable tar with fresh-slacked lime in the proportion of one barrel of the former to one bushel of the latter; the mixture to be well boiled and applied freely while hot. At the works wire rope is reeled up under strong tension, and in reel- ing off for use it should be passed directly from one reel to the other under at least slight tension, and it never should be coiled down or faked by hand. When supplied in a coil, the coil should be rolled along like a wheel and the rope payed off in that way to the working reel. * Two lengths tested for strength in kinlcs gave breaking strains as follows : 4,410 pounds, 4,600 pounds. April, 1880. 156 DEEP-SEA SOUNDING AND DREDGING. For joining two lengths of the rope a "long-sphce" should be made, at least twenty feet in length. To make an eye-splice at the end of the dredge-rope, turn the end of the rope around an oblong or heart-shaped thimble, and unlay each wire from the thimble to that end. Lay these wires as an untwisted strand along the rope and serve wires and rope together tightly with annealed-iron wire for a distance of eight or ten inches from the thimble. Cut off the free ends of the wires about three-quarters of an inch above the serving and turn down each wire neatly along the serving. The dredge, trawl, &c., should always be attached to the rope by a shackle. We at first used hooks which we moused with wire, but they always broke adrift, probably by bending. Long shackles should be selected, of a size to slip into the thimbles, and into the eyes in the arms of the dredge. I would call particular attention to this matter, hoping to prevent a resort to makeshifts. THE DREDGE-REEL, For dredgjng in depths no greater than five hundred fathoms, which would require the use of no more than 1,000 fathoms of rope on the work- ing reel, the latter might be made part of the hDisting-engine and be geared to the crank-shaft. The advantage would be in compactness and simplicity. For general work, the plan adopted for the "Blake" is probably better. When the reel takes the full strain on the rope in hauling back great strength is needed to resist the crushing force accumulated upon the drum, and to adapt a reel capable of holding four or five thousand fathoms of rope to this strain would involve an increase in its weight by no means desirable, either for paying out rope or for planting on a vessel's deck. The "Blake's" reel, which has held 4,200 fathoms of the steel dredge- rope, is best shown on Plate 32. The drum or barrel is of boiler-iron, three feet six inches long, two feet in diameter, and riveted to fillets on the two cast-iron side-plates. The depth of the flanges, above the drum, is one foot. The side-plates are made with spokes, but would be better if solid. The friction-band is of wrought-iron, lined with maple one inch thick. The standards are of cast-iron and are higher than need be. They were designed when it was intended to wind the rope by means of the r > DREDGING AND TRAWLING— APPARATUS AND METHODS. 157 hand-cranks. When a steam-engine is used for winding, the reel should be set as low as poss-ible for security against the rolling of the vessel. In designing standards for a leel it must be remembered that they should be adapted to withstand violent jerks. The axle of the "Blake's" reel is of wrought-iron two and seven-eighths inches in diameter, reduced to two and five-eighths inches in the journal-boxes. The axle should have a bearing on both sides of each journal-box in order that the lateral strain may come upon both standards at each roll of the vessel. The friction-lever is of the double-acting kind; that is, both ends of the friction strap or band are l)olted to the lever, one on each side of the pivot. Neither the friction-score nor the bearing surface of the friction-band should be lubricated with oil. Water may be used, if necessary, to pre- vent the wood lining from taking tire, but it should be applied at intervals from the first, and not dashed on when the cast-iron reel is hot and likely to be cracked by a sudden change of temperature. The "Blake's" reel cost $225, and was made by Messrs. Gopeland & Bacon, of NeAv York. THE STEAM HOISTING AND WINDING ENGINES. ( Plates 32, 33, and others.) The Hoistinu-enaine. — There are two trunk cylinders, of the pattern known as Bacon's patent (see Plate 18), each of ten and one-half inches bore and ten inches stroke, firmly secured to the bed-plate at an angle of 45°, thereby avoiding a dead center, both being connected to the same crank-pin. The engine is provided with "link-motion" so that it may be run forward or backward or stopped instantaneously by the operation of the reversing lever, which is fitted to lock in three positions. By its elastic flexure the lever in locking is thrown into jogs cut in the flange of the standard against which it presses. The after lever, working in a vertical plane, as shown on the plates, is the reversing lever. The crank-shaft is single-geared to the shaft of the winch-head by strong spur-gearing in the proportion of three to one. The winch-head, which is 22.56 inches in its least diameter — to accommodate one fathom of the li-inch dredge-rope in a single turn — is keyed to its shaft, the latter working within the larger gear-wheel. The winch-head shaft is fitted 158 DEEP-SEA SOUNDING AND DEEDGING. with a clutch working on a feather and operated by a lever moving in a horizontal plane. This lever may be locked in position by means of a thumb-screw. The winch-head may thus be thrown into gear with the engine, or it may be thrown out of gear and overhauled independently of the engine. The winch-head is provided with a powerful friction-brake, operated by a lever. On Plate 33 this lever is shown thrown up, in which position it is locked or latched in a jog cut in the flange of the forward standard, the friction-band being out of contact. One end of the band sets up with a screw and nut to a lug cast on the standard. The other end of the band is fastened by a pin to an arm projecting from the shaft to which the lever is keyed, the arrangement forming a toggle-joint, by means of which the lever is automatically locked when thrown down to its lowest position — that is, when the greatest stress is upon the band. The ultimate stress may be regulated by the screw and nut at the standing end of the band. This provision is necessary because the wood lining of the band will slowly wear away in use. Below the brake-lever is the throttle, the wheel of which is made large that it may be turned easily and delicately with the left hand when the right hand is engaged with the brake-lever. On the hub of the winch-head is a steel worm to engage the gears of a register like that shown on Plate 38, The register gives, approximately, the number of fathoms of dredge-rope payed out. On the after end of the crank-shaft, outside of the fly-wheel, is a small winch -head for general use. The crank-shaft is forged in one piece, and both this and the winch-head shaft are of the best wrought-iron. The journal-boxes, connecting-rod boxes, and link-blocks are of composition metal. All pins for valve-motion are of steel, and all parts of the engine are made extra strong to withstand violent shocks. " The engine may be run fast or slow according to the work to be done, and under the complete control of one man. The pressure of steam is usually sixty pounds. The exhaust leads into the condenser of the main engine. The cost of the hoisting-engine, fitted in place and in running order, was $1,150. DEEDGING AND TRAWLING— APPAEATUS AND METHODS. 159 Tue mfi«iiii»-e«ffi»ie,— This is of the same general description as the hoisting-engine. It has two six-inch cyhnders and is single-geared to the axle of the dredge-reel. It is fitted with reversing and clutch levers arranged for locking in position. Engine and reel are under the control of one man. The cost, placed on board and in running order, was $485. THE SWINGING BOOM. This is so clearly shown by the heliotype views that an extended explanation of details is not needed. It was forty-seven feet long and fourteen inches in its greatest diameter. The metal fittings and fasten- ings were of wrought-iron. The topping-lift was of three-inch manila, rove through iron-strapped blocks made extra strong. The pendant was of 4J-inch manila. The small block at the boom-end was of a well-known commercial pattern, extra fastened under my direction. The pendants of the guys were of two-inch iron-Mire rope, and the falls for the same of 2^-inch manila. THE ACCUMULATOR OR DYNAMOMETER. (Fig. 3, Plate 34.) The accumulator for dredging is made of a number of rubber buffers, A, A, &c., arranged for compression on a rod, B. The buffers are separated from each other and from the rod B by the guide-plates G, C, &c. The upper end of the accumulator being secured at D, and a strain applied to the lower end at E, the compression of the buffers will permit the cross- head F to travel along the rod B, and the rods G G to travel through the guide-plate H and the cross-head I. In this manner the accumulator elongates under strain, and when released from strain it is restored to its former length by the elastic force of the buffers. The buffers are three inches deep, four and a half inches Avide, and have a cylindrical hole through them of one and a quarter inches diameter. They were purchased of the New York Rubber Belting Company, of Park Row, New York, at a cost of about $2 each. The material of which they 160 BEEP SEA-SOUNDIKG AND DBEDGIKG. are composed is known by that company as compound No. 24, the con- stituents of which are as follows : Ten pounds fine Para rubber, cleaned. One pound white lead. One pound litharge. One pound whiting. Ten ounces sulphur — about. Vulcanizing heat, about 260° Fahrenheit. The rods B and G, G, the nuts, the cross-heads F and I, and the large guide-plate H are of steel; the guide-plates C, G, C, &c., are of brass; all other metal parts are of wrought-iron. The guide-plates C. G, G, &c., are one-eighth inch thick throughout the flanges. Their hubs are made to fit loose on the rod B, but tight within the buffers. The edges of the metal around all holes in the guide-plates and cross- heads should be slightly beveled to obviate friction and planing. The rod B accommodates thirty-two buffers without compression, but seven more are forced on that the accumulator may not extend for a light strain. Neither an accumulator nor a dynamometer is of use excepting for a severe strain. Plates 13 and 14 show the accumulator lowered into view: Plates 1 and 24 show it in its proper place, suspended from the mast-head. It is very elastic, and seems to have answered the purpose for which it was intended. Its maximum extension is about six feet. If I were to suggest any improvement at present occurring to my mind, it would be to make the buffers of a compound which would offer a greater resist- ance to compression. The total cost of the apparatus was about |130. The only really novel feature given by me to this accumulator is the peculiar shape of the brass guide-plates G, G, G, &c., the hubs or fillets of which keep the buffers from coming in contact with the rod B when the buffers are compressed. If fears were entertained of the accumulator giving way in use, a toggle might be put in the pendant somewhere above the heel of the boom. DEEP-SEA SOUNDING AND DREDGING V. S. COAST SURVEY PEATE 34. Pa Co J 6) FIG'S. 1& 2. IRON SNATCH-BLOCK FOB DREDGING ROPE. FIG. 3 IMPROVED ACCUMULATOR FOR DREDGING. DREDGING AND TRAWLING— /APPARATUS AND METHODS. 161 THE IRON SNATCH-BLOCKS. (Figs. 1 and 2, Plate 34.) These are the hlocks through which the dredge-rope leads. The pins or bolts A, B, C should be of steel, the sheave D of cast-iron, the side-plates E, E of thin plate-iron, and the flap or hook F and the straps G and I of wrought-iron. In the deck-blocks the side-plates are free to revolve, but on the pendant-block at the boom end they are pinned to the strap G, and are connected by socket-bolts at the points X, X, X. The socket-bolts are to prevent the dredge-rope from getting between the side-plates and the strap G. In setting up the socket-bolts care should be taken not to bind the side-plates against the sheave. The dimensions given on Plate 34 are those of the deck-blocks; the pendant-block has a sheave one inch wider. Plate 31 gives a view of the deck-blocks. 21 D s APPENDIX TO CHAPTER V. DESCRIPTION or SOME OF THE APPARATUS USED BY THE UNITED STATES COMMISSION OF FISH AND FISHERIES IN DREDGING OFF THE NEW ENGLAND COAST. By Pbof. a. E. Vekrill. THE KAKE-DREDGE. This instrument was devised in 1871, by the writer, for the special purpose of obtaiuing deep-burrowing species of bivalves, annelids, holothurians, Crustacea, «&c. It can be used only on muddy or sandy bottoms, and, of course, requires considerable force to draw it through compact mud or sand. In its original form, which is still in use, it consists of a strong A-shaped frame, made of flat bar-iron, and so bolted together that it can be folded up compactly when not in use or for convenience in transportation. The rakes consist of two flat bars of iron, furnished with strong iron teeth (steel would perhaps be better), about a foot in length, with thin, sharp edges and sharp point. The two rake-bars, when in use, are placed back to back and bolted to the ends of the side- pieces of the A-shaped frame. The cross-bar of the A projects beyond the side-pieces, and has a hole at each end, by which the arms of the dredge-frame are attached, so that the dredge follows the rake at a distance of about two feet. The dredge-frame for this instrument is made entirely of round iron, and as light as is consistent with the stiffness necessary to support the bag full of mud when being hoisted on deck. The length of the frame should be equal to, or somewhat exceed, that of the rake-bars. In the one now used by the Commission it was originally considerably larger, but owing to the too great weight of the load of mud it brought up, it has been made smaller, so that it is now of about the same length as the rake-bars. The net is similar to that of the common dredge, but deeper and with somewhat larger meshes, in order that a part of the mud may pass through more rapidly. The vast quantity of annelid tubes often encountered in using the rake-dredge frequently clogs the net so as to pre- vent even the tine mud from passing through the meshes. As this form of dredge can only be used on smooth bottoms, there is not so much need of a canvas protection as in thje case of the common dredge, and we have often dispensed with it, but the net will doubtless last longer if protected with the canvas bag. The dimensions of the rake-dredge used by the Fish Commission are as follows : Indies. Side-pieces of tlie A-shaped frame : Length 30 Width 2 Thickness | Hole for ring | Bolts f 163 164 DEEP-SEA SOUNDING AND DEEDGING. Rake-bars (d) : Length Width Thickness Teeth of rake : Length Width Thickness Ring for drag-rope : Diameter Size of iron Dredge-frame (a) : Length Breadth Length of arms Size of iron (round). . Depth of net (6) 2i I 8 li I 3i I These dimensions miglit be improved by making the teeth ten inches long, and at least one-half iucli thick if of soft iron, and they might have a slight forward curvature. The head pass- ing through the bar should be square, and about three-fourths of an inch thick. They might be fewer and farther apart without detriment — say, five teeth on a bar three feet long, leaving the spaces about six inches each. The use of steel of low temper would be better still. The round iron for the dredge-frame should be at least five- eighths of an inch in diameter for the size of net given. THE TANGLES. The original form of tangles constructed by the writer for theUnited States Fish Commission, in 1871, consisted of a bar of iron to which several sm all iron ch ain s were attach ed , each about fifteen feet in length. Along these chains, at intervals of about three feet, the bundles of unraveled hemp rope were attached, as shown in the figure. The bar of iron carrying the chains was attached to the cross-bar of the A-shaped frame forming part of the rake-dredge, the rake-bars being removed. In 1873 a fur- ther improvement was made by the writer. This consisted in supporting each end of the chain-bar in the center of a stout iron hoop or wheel by bolting it to a central cross-bar firmly bolted to the inner side of the wheel. The wheels are not intended to revolve, but merely to serve as runners and supports for the iron bar, in order to keep it oft" the bottom and diminish the chances of its getting caught among the rocks, as well as to keep it from breaking and destroying the specimens before the tangles them- selves can touch them. An oval or elliptical form for these runners would answer the -The Eake Dredge. DEEDGENG AND TRAWLING— APPARATUS AND METHODS. 165 same purpose, but the circular form was adopted as the simplest, and, perhaps, the least liable to become caught among the rocks. In practice we have found the tangle-frame hitherto used too light for use on the larger vessel now em- ployed, for when rocks are encountered the chain- bar often comes up badly bent. In constructing new ones, I should recommend a round or square bar of iron at least twice as heavy as the one we have hitherto used. Our present size was first devised for use on a steam-launch. It was also used on the "Bluelight," a tug of eighty tons, with good success. We have used tangles of this form with profit on the roughest cod-fishing ledges off the coasts of Maine and Massachusetts, where the dredge could not be used with safety. It is par- ticularly useful in capturing starfishes and sea- urchins, which frequent rocky bottoms. Several years ago the writer suggested the use of tangles of this or similar form to capture star-fishes on oyster-beds, where they so often prove very de- structive. I.— The Tangle-Bar. DIMENSIONS OF TANGLES, Diameter of wheels outside Breadth of rim of wheels Thickness of rim of wheels Width of cross-bar of wheels Thickness of cross-bar of wheels Length of chain-bar Width of chain-bar Thickness of chain-bar Size of rings for drag-rope Size of iron of rings Size of iron of chains Length of iron chains , Length of hemp tangles design. 12 inches. 2 inches. 1 i inch, i 2 inches. | I inch. 48 inches. 2 inches. i inch. 3 inches. f inch. i inch. 14 feet. 2i feet. 14 inches. 2i inches. 2^ inches. I inch. 60 inches. 2^ inches. 1 inch. 4 inches. f inch. I inch. 16 feet. 3 feet. The drag-rope for the tangles should "be very strong, to resist the frequent and sudden strains when using them on rough bottoms. 166 DEEP-SEA SOUNDING AND DEEDGING. THE CHECK-STOP. This arrangement was devised by Oapt, L. A. Beardslee, for use on board the ■' Bluelight," in 1873. Its piirpose is to put the strain of the drag-rope (B) upon a weaker rope (0), which may be so easily broken in case the dredge or trawl catches upon rocks as not to cause damage to the apparatus, and at the same time to give sufficient warning to allow the slack of the drag-rope to be payed out before the head- way of the vessel can be stopped. It has proved to be a very useful and simple expedient for these purposes. The figure shows the arrangement so well that no fur- ther description is necessary. THE CEADLE-SIEVE. This form of sieve was devised by the writer in 1872. It was so constructed as to afford the means of rapidly washing out the large quantities of mud often brought up by the dredge and rake-dredge, and at the same time to keep the mud and water off" the deck as much as possible. It consists of two wooden end-pieces, in shape forming rather more than half a circle, united by two narrow wooden side- J.— Beardslee's Check-Stop. pieces set into the end-pieces so as to leave a flush surface. The outside covering consists of two thicknesses of wire netting, the inner one with meshes of one-twelfth inch or less ; the outer one of stout galvanized- iron wire with one-half-inch meshes. The outer netting is only to afford support and protection to the inner one. The netting- is nailed to the edges of the wooden end- pieces and to the side-pieces, and is further secured by a strip of hoop-iron nailed over the edges all around. A strip of wood, nailed across the bottom from end to end, affords additional strength and protection from injury. Two stout iron straps, fastened across each end-piece by wood screws, and K.— The Cradle-Sieve. terminating above the edge in a ring, fur- nish the means of suspending this sieve against the side of the vessel outside the rail. The mud is then placed in it, often filling it more than half full, and a gentle stream of water from the force-pump is turned upon it. In this way several bushels of mud may be washed out in a few minutes with little trouble. Another sieve, with straight wooden sides about six or seven inches high— just large enough to set partially into the DKEDGING AND TEAWLING— APPAEATUS AND METHODS. 167 frame of the cradle-sieve and rest upon wooden cleats, provided for that purpose — has been sometimes used iu connection with the cradle-sieve. Its bottom is made of strong galvanized-wire netting, with meshes of one-half inch. It serves to separate the coarser specimens and stones from the smaller and more delicate species. In our own work the table-sieve described below has, to a considerable extent, superseded the cradle-sieve. The latter is still used, however, when there is only a moderate quantity of mud or when the table-sieve is already full of specimens. DIMENSIONS OF CRADLE-SIEVE. Inches. Length 36 BreadtH 18 Depth 12 Width of side-pieces 3^ Thickness of side-pieces and ends 1 THE TABLE-SIEVE. improvements. In This piece of apparatus is the result of several successiv fundamental principle it is like the cradle-sieve much enlarged and raised on legs, but the form is entirely .different. The sieve-foundation con- sists of a large, rectangular, wooden frame (0, Fig. L), with wide side-pieces made of inch boards, supported on stout legs at a convenient height. The bot- tom of this frame consists of stout galvanized-wire netting with one- half-inch or three-fourths-inch meshes. Below this is a funnel- shaped stout canvas bag (s), which terminates in a large can- vas tube [t). This serves to con- duct the waste water to the scup- pers. A light frame of wood (B) is made to fit loosely inside of the L.— The Table-Sieve. main frame, and its under surface is covered with fine wire netting of one-twelfth-inch meshes. This constitutes the real bottom of the sieve, the coarse netting below serv- ing only as a support for it. It is fastened to a movable frame, so that it can be taken out and its contents emptied upon the assorting-table. This also allows the wire net- ting to be more easily renewed when it becomes worn. The upper or coarse sieve (A) is made with wide, flaring, or hopper-shaped, wooden sides, upon which, at about the middle, there are cleats (e, e) that rest upon the edges of the main frame. The bottom of the "hopper" is formed of strong galvanized-wire netting of three-fourths-inch meshes (Fig. M, &, b). 168 DEEP-SEA SOUNDING AND DEEDGING. DIMENSIONS OF TABI,E-SIEVE. Main frame : Height to upper edge Length Breadth Width of side-pieces Thickness of side-pieces . . Hopper-frame : Width of side-pieces Length at bottom Length at top Breadth at bottom Breadth at top. 37 This form of sieve, iu its primary form, was invented by Oapt. H. 0. Chester and the writer in 1877, but it was soon afterwards much improved by the addition of the canvas bag and pipe beneath it, which were devised by Mr. Smith, the execu- tive officer of the "Speedwell." The original use of this sieve was to receive the contents of the trawl, instead of emptying it on deck, as had been done previously ; but its advantages were soon found to be so great that it has also been used for washing the contents of the dredge whenever the quan- M.— The Table-Sieve. tity of mud was considerable. The legs are made of unequal lengths, to correspond with the curvature of the deck. CHAPTER YI. NAVIGATION AND KECOEDS. DEVISING A SYSTEMATIC RECORD. Until the records of the "Blake's" work were systematized in the man- ner to be described in this chapter, deep-sea parties of the Coast Survey had not been required to render to the office a detailed record of navigation; the work having been more or less desultory, there had been no general con- formance to a fixed system of record analogous to that demanded of inshore parties, and the results of the navigator's observations and computations for determining positions had usually been accepted as correct. On joining the vessel I was the bearer of instructions from the Superintendent to my pre- decessor in command to submit to the office, with other records, the data used by the navigator in fixing the positions of soundings. While Commander Howell was still in charge forms for computation, containing the arrange- ment of data shown below the headings of Forms 7, 11, and 12, were drawn up by Robert G. Peck, Master, one of the watch officers of the " Blake," and were approved by the commanding officer. The system of navigation record, as set forth herein, was then gradually developed during my first and second seasons in the Gulf of Mexico, some preliminary points having been dis- cussed before Commander Howell left the vessel. In the astronomical meth- ods employed to determine positions we made no advance; it was only in combining in a comprehensive system the work of navigation, plotting, and record, to admit of a revision of the whole navigating work at any future time, that we afterwards made any improvement in the department of navi- gation. From the impetus and scope given to the work by the adoption of wire for sounding purposes it followed, not unnaturally, that the arrange- ment of the General Record Form (Form 3), i. e., the record of soundings, 22 D S 169 170 DEEP-SEA SOUNDING AND DEEDGING. temperatures, &c., needed to be changed, and as additional forms became necessary we from time to time drew up and introduced all others shown in this book. Our efforts in this direction were, in the main, simply res- ponsive to the new recjuirements. Merely to plot a ship's positions for the times of observation is easily done by a navigator, but when the position of every sounding and of every change of the course must also be plotted, and all the processes clearly explained and submitted to the judgment of others, the work becomes compli- cated, and inevitably suggests the necessity for system to a person plotting in a maze of right lines, and surrounded, perhaps, by sixty, eighty, or one hundred Navigation Forms and other papers. While my written description is undoubtedly very dry reading, the system itself is nevertheless so simple that with the opportunity for verbal explanation it was only the work of a few hours to qualify a new officer reporting for assignment as executive and navigator. WHAT CONSTITUTED THE RECORD. On fitting out for each season the party was provided by the office with one or more Projections or Sounding-Sheets (Fig. 2, Plate 35) covering the whole ground to be worked over. They were on a scale of either .ook or eooVo, and on them were located all the prominent landmarks likely to be needed for beginning or closing the inshore ends of lines of soundings. The various forms used in our work were also provided as required. The record of the work consisted of the following: jFor the Coast Survey Office.— TliB General Rccord, Fomi 3, aud the Sup- plementary Record, Form 4, with which were bound in one volume the following: List of officers of the vessel, copy of the Superintendent's letters of instruction, diary of events, special tabulated statements, deviation tables, description of apparatus and methods, &c. The Navigation Record, Forms 6 to 12, bound in one or more volumes, and showing the data and methods employed in fixing the positions on the lines of soundings and in determining chronometer errors. The Sounding-Sheets, represented herein by Fig. 2, Plate 35, contain- ing, besides the plotted work, tabulated statistical statements of the amount of work done during each season. NAVIGxlTION AND RECORDS. 171 Temperature Curves or Sections, Form 15. For the Atehivea of the Vessel. — The Original, or rougli slieets, of every- thing sent to the office, excepting the Sounding-Sheet, of which a tracing was kept. The Sounding Time Book, Form 1. The Serial Temperature Book, Form 2. The Plotting Form, Form 13 (B). The Plotting-Tracing, Fig. 1, Plate 35. The Rough Book of Observations, Form 5. EXPLANATION OF RECORD FORMS. For an explanation of our system, it is well to describe the record — in all the essential points — of some particular line of soundings, and I have selected for this purpose the record of a part of line S, of 1875-76, in the Gulf of Mexico, carrying it through one day only. As this line was run from South Pass, Mississippi River, to the Yucatan Bank, nearly on the meridian of 89°, to continue the record along the whole line would be sim- ply to repeat the first day so far as the purpose in view is concerned. As a preparatory measure an explanation of some features of the forms will be given. The General Meeord, Form 3.— ColumUS A, B, G sllOW tllC time wheU the sinker reached bottom, which is regarded as the time of the sounding, and that on which the position of the sounding should be based. Column D shows the serial number of the sounding, to which number are referred all the specimens taken at the cast. At sounding No. 10, for example, we obtained and saved for examination a bottom-soil specimen and six water specimens, all of which received the number 10, on the bot- tle labels. In referring any specimen to its corresponding sounding on the General Record, the serial number on the label would show beyond question — and without reference to the latitude and longitude — at which sounding the specimen was secured, even had two or more successive soundings shown equal depths. See bottle labels on page 90. Columns E, F, G, H are arranged to give continuity to the data 172 DEEP-SEA SOUNDING AND DEEDGING. required by the draughtsman at the office in plotting soundings on the office sheets; that is, the data for chart-making. Columns I and J show the corrected water temperatures (the readings of the instruments and the corrections to be applied are kept on Form 2, page 104) . These columns are not filled by the recorder during the work on deck, but the entries are made afterwards when the instrumental errors have been applied. Column K shows the temperature of the water specimen at the instant of reading the density from the areometer in order that the density of each specimen may be reduced for a common temperature. The depth whence the specimen came is referred to the column of depths under the head of '^ water temperatures.'' Columns L, M, N, 0. — A comparison of these columns gives the whole time occupied at a sounding station, which it is well to know for various reasons, and gives also the figures for Columns P and Q. Columns P and Q show the time taken to make the run from the pre- ceding sounding or change of the course, and are of use, in connection with column T, in giving the officer of the deck an idea of the time required to run the distance from the station last occupied to the one next in order. For example: Master M. F. Wright relieved the deck at 4 a. m.. May 10, and, seeing that it had taken the vessel, in Lieut. W. 0. Sharrer's watch, 1'' 10"" to make 9,7 miles, from sounding No. 4 to sounding No. o, it appears that he allowed I'' 12"" from sounding No. 5 to sounding No. 6, hoping in that time to make the exact sounding-interval of ten miles. Column R shows at each sounding or change of the course the vessel's course by the standard compass from the preceding sounding or change of the course, and is the column to be filled by the officer of the deck, leaving the corrections to be applied afterwards by the navigator. Column S shows the reading of the patent-log at each sounding and at each change of the course. Surface currents recorded on the General Record do not necessarily apply to the plotting; each is obviously only the true current at one obser- vation spot and for one short interval of time. It will be seen that the arrangement of the General Record Form is NAVIGATION AND EECOKDS. 173 designed to give, so far as space will permit, a general grouping of the data needed for scientific investigation on one page and tliat for the navigating purposes of the vessel on the other. The Supplementary Record, Form 4. — Tllis iS Of USC iu making Up the statistics of lines of soundings, in preparing detailed reports of operations, and for general reference. It shows what instruments and appliances were employed, and if their working was satisfactory. The categorical style of the headings of some of the columns was suggested by experience, and after its adoption we were free from ambiguities of expression, such as "bottom saved," "got bottom," "bottom specimen," and the like, which left one in doubt as to whether a specimen of the bottom had been saved for examination in every case or only in certain instances. Column F of the General Record points out, by the absence of abbre- viations or by special statement, if no specimen was brought to the surface. T/ie Rough Rook of Observations, Form S. — Books COUtaiuiug fifty leaVeS, having these forms printed on each page, were bound in suitable style for the pocket, and the navigators used them in all astronomical observing. It was the custom of the "Blake's" navigators to take one or more observa- tions at each sounding during the day and frequently between soundings also, while at twilight, both morning and evening, they continued to get them as long as the twilight gave a bright star above a distinct horizon. The intention was not, necessarily, to compute all, but to have them avail- able should those which were computed fail to give good results. With Form 5 is given the label for the cover of the Rough Book of Observations. The Navigation Forms, Forms 6, 7, 11, and 13. — ThCSe are the OUly formS used on board the "Blake" for the computation of astronomical observa- tions, and, with the remarks written upon them, they constitute the whole navigation record sent to the office, excepting the data contained on the General Record Form. Form 6 is for computing chronometer errors by Equal Altitudes, for recording positions by bearings, and for all computations for which the arrangement of Forms 7, 11, and 12 is not adapted. Sumner's Method by Moon, Planet, or Star may be worked on Form 174 DEEP-SEA SOUNDING AND DEEDGING. 7; Sumner's Method by the Sun on Form 11; and the Meridian Altitude of Sun, Moon, Planet or Star on Form 12. The occasion was very rare that required the use of Form 6 when working on our lines. Forms 7, 11, and 12 were employed almost exclu- sively, full advantage being taken of the comprehensive scope of Sumner's Method. T/te Plotting Form, Form 13 (A and B) . — Thls Is uot indispcnsable, but its use systematizes the work of plotting and thereby very much lessens the probability of making errors. It was regarded by us as a great con- venience, and its use will become apparent when the plotting of the work is explained. SCHEME OF NAVIGATION RECORD, When at work on a line of soundings the navigators arrange the com- puted observations in order of time, for convenience of reference. After the arrival of the vessel in port, and when the chronometer errors have been ascertained, the chronometer rates are worked back for each day on the line. Then each observation, beginning with the first of the series, undergoes a verification by the assistant navigator, the new chronometer rates being introduced. The executive officer, who is also the navigator, beginning with the line first run, and keeping each line distinct, selects such observa- tions as are deemed worthy of consideration, and, still preserving the order of time, numbers them in a regular series by numeral letters as they come from the assistant navigator. After a few observations have been verified the navigator begins the plotting, and the work of verification and plotting go on together, usually keeping pace with each other. After the plotting has been completed the accefted observations — those not rejected as the plotting advances — are renumbered in a new series by order of time, and are designated by the numeral figures. The rough copies of the Navigation Forms retain the symbols of the first numbering, and receive also those of the second series, but the smooth copies sent to the office bear only the numeral figures — that is, the revised numbers. Thus we have the selected observations numbered in two series, one series embracing all that were selected and considered, and the other series only those that were finally accepted in the plotting. NAVIGATION AWD EECOEDS. 175 The utility of numbering in a series all tlie observations to be con- sidered is, I think, apparent, and it is probably equally clear that a renum- bering or a rearrangement of the accepted observations in a second series is necessary in order to restore the continuity of a first series that has been broken by the rejection of some of its component parts. Since an obser- vation may have a different number in the second series from that which it had in the first, to escape confusion a distinct notation or symbolization must be adopted for each series ; hence the employment of both numeral letters and numeral figures. Throughout the Navigation Record no other use is made of the Roman numerals than that already specified. Each line of soundings of any season is designated by a letter accord- ing to alphabetical order and order of time, and all specimens, soundings, stations, observations, positions, &c., on a line are referred to the line letter. On the Navigation Forms the various positions established by astronomical observations or by bearings of objects on shore are also marked serially in order of time, and on the Sounding-Sheet are designated by symbols such as Si, S2, S3, &c., for line S. The use of the symbols will be appreciated when it is called to mind that upon the Sounding-Sheet may be plotted many intersecting lines of soundings, each line exhibiting a number of Definite Positions obtained by observation. On board the "Blake" a person would be readily understood were he to say that Sounding 13, on Line S of 1875-76, was taken at Position 10, or Sw, determined by Observations 8, 9, and 10. HOW TO KEEP THE PLOTTING FORM; ITS USE. In plotting a line of deep-sea soundings, as in plotting an inshore line, the line itself is first laid down by fixing and connecting the successive positions obtained by observation, after which the soundings are located on the line as thus laid down. It is very confusing in plotting to be obliged to refer, forward and back, repeatedly to the General Record and the many Navigation Forms, on which there is avast deal of data of no use in plotting; but with the Plot- ting Form this necessity is obviated, for on the latter, by a preliminary 176 DEEP-SEA SOIJKDING AND DEEDGING. operation, all the necessary data, and no more, are arranged and combined in such a way as to facilitate subsequent selection and comparison. Form 13 A shows the Plotting Form fully prepared for beginning the plotting of line S, while Form 13 B shows its condition when the plotting has been completed. All the bearings, angles, and astronomical observations to be considered in plotting the work are arranged on the Plqtting Form (Form 13 A) in order of time; the observations are numbered in Roman numerals in a regular series, and the data for laying down the lines of position, together with the courses and distances that have been made to each observation or change of the course from the preceding observation or change of the course, are correctly placed in their appropriate columns. A change of the course, when there is no corresponding observation, is designated by the letters C, C in the " ohjecf column, and to secure a proper spacing it should be entered as soon as its place has been reached, and not after all the data from the various Navigation Forms have been first entered throughout the whole Plotting Form. The courses and distances are obtained by an inspection of the^cowrse" and ''patent-log'' columns of the General Record Form in comparison with the patent-log readings on the Navigation Forms. Confusion may arise herein if it be not borne in mind that the courses and distances are arranged on the General Record in their relation to the soimdings, while on the Plot- ting Form they are arranged in their relation to the observations. As an example of a case in which a mistake might be made if care were not exercised, it will be shown how the courses and distances are entered on the Plotting Form between Observations IV and V. There are given liereAvith specimens of only seven of the completed Navigation Forms. Their serial numbers happening to be the same by both numeral letters and numeral figures, they have been marked on the headings with the numeral figures only as being smooth copies. After entering these specimen observations on the Plotting Form, the results of others, of which no specimen copies are thought necessary, have also been entered in order to complete the record for one da}'. Observation IV was taken between Soundings 5 and 6 (shown by the back of the Navigation Form, or by a comparison of the reading of the patent-log on the General Record with that on the Navigation Form). From the time of the observation, when the patent-log read 46.4 miles, the NAVIGATION AND KECORDS. 177 General Record shows that the vessel continued on a S, I E. course until Sounding 6, when the patent-log read 50.4 miles — a distance of 4 miles. Immediately after Sounding 6 the course was changed to south (see Gen- eral Record, Sounding 7, '' course from last sounding''), and remained un- changed at Sounding 8, when the patent-log read 70.2 miles — a distance of 19.8 miles. Observation V was taken at Sounding 8, as the patent-log readings at once show, and thus it should be entered on the Plotting Form, between the records of Observations IV andV, that the course was changed at S*" 25™ a. m. (assumed to have been changed from the time the sinker touched bottom at Sounding 6), when the patent-log read 50.4 miles, and after the vessel had steered S. I E., 4 miles, since Observation IV; and for Observation V it should be recorded that the vessel had steered south, 19.8 miles, since the change of course mentioned. As the plotting of the work progresses and the location of the Definite Positions are determined, the method followed in getting each of these posi- tions from the observations is stated in the second column of '■'remarks'''' on the Plotting Form. It should be borne in mind by the person who plots the work that while his memory is charged with many important facts concerning the navigation of the vessel, these facts will be altogether out of the reach, excepting through the records, of those who may in the future revise his work. His aim should be, therefore, to prepare the "remarks''' for the benefit of persons who understand plotting, but who are unfamiliar with the circumstances attending the work itself. A similar principle should be applied to all the records. The first column of "courses and distances" on the Plotting Form is made to show, at each observation or change of the course, the run from the preceding observation or change of the course with reference to all the observations which were placed under consideration. The second column of "courses and distances" is used to rearrange the traverse data to suit the accejpted observations only. Thus, for example. Observations VIII and IX (Form 13 B) having been rejected in the plotting, the columns are made to show in the simplest form the run to the accepted Observation 8 from the accepted Observation 7 (to Observation X from Observation VII) . By the 23 D s 178 DEEP-SEA SOUNDING AND DEEDGING. first column of ^'courses and distances" the run to Observation X {acce^pted Observation 8) from Observation VII {accejpted Observation 7) reads S. by E. I E., 10.3 miles, S. t E., 5 miles, and S. i E., 5.3 miles, while in the second column it is stated compactly as S. by E. I E., 10.3 miles, and S. t E., 10.3 miles. When the plotting has been completed, the ''remark'' column filled out, the second numbers given to the observations, and the latitude, longi- tude, and serial number of each Definite Position recorded, we have on the Plotting Form, exclusive of the computations of observations, all the infor- mation needed to effect a replotting of the Definite Positions on the line of soundings by either series of observations. There should be transcribed from the Plotting Form to the rough Navigation Forms all the explanatory remarks from the second column of "■remarks'' ; also, the latitudes, longitudes, and serial numbers of the Definite Positions. I will again state that the rough Navigation Forms, both on the headings and in the remarks, should give the observation numbers in both series; but the smooth copies, for transmission to the office, should give only the numbers in the second series. The forms of those observations which are thrown out in the plotting are marked "■Rejected," in large letters across the face, with red or blue pencil, and may be filed away in the Archives with the rough forms of the accepted observations or by them- selves. We never sent the Plotting Form nor the Plotting-Tracihg to the office because, the ''Blake's" work being continuous, the party on board could always be called on by the office for a replotting; but with a brief explanation on the Plotting Form, to show the use of the first and second arrangement of numbers, courses, and distances, that Form and the Tracing might form very useful additions to the office records. THE ARCHIVES. The establishment of the Archives was by no means a caprice; on the contrary, it was a legitimate consequence of the many embarrassing circum- stances which suggested it; and it can be stated with confidence that, by taking a great number of observations, by recording them with full infor- mation in the systematically arranged Rough Book of Observations, and NAVIGATION AND EECOEDS. 179 by preserving all of them for future reference, many miles on lines of soundings were saved which otherwise would have been lost. THE PLOTTING-TRACING AND THE SOUNDING-SHEET. It grew to be our custom to plot, not directly on the Sounding-Sheet, but on a piece of tracing-paper laid over it and upon which were traced the parallels, meridians, compasses, and graduated scales required to plot the line of soundings in hand (Fig. I, Plate 35). By pricking through the Tracing positions could afterwards be transferred readily to the Sounding- Sheet. The finished Sounding-Sheet (Fig. 2, Plate 35) contained on each line the Definite Positions, the points where the course was changed, the soundings, the character of the bottom-soil specimens, occasional surface currents by dead-reckoning or by actual observation with floats, and the direction of the wind at frequent intervals. When the transfer had been made the Tracing was cleared of all superfluous pencil-marks, and filed away in the Archives on board the vessel, where it remained from year to year for reference. In case lines of soundings subsequently run did not intersect consist- ently with lines already plotted, the Plotting-Tracing was taken from the Archives and the plotting work subjected to a careful revision. This Trac- ing, besides greatly facilitating revision, saved the Sounding-Sheets from much of the wear that would have defaced them during the successive seasons that they were used on board the vessel. Although the Sounding-Sheets were sent to the office at the end of each season, they were usually returned, after being copied, to serve for further work in the same locality. Fig. 1, Plate 35, shows the Plotting-Tracing of Line S cleared of superfluous pencil-marks and ready for the Archives. DETAILS OF THE PLOTTING OF LINE S. Estahusuina the Positions (Fig. 1, Plate 35). — By reference to the Plot- ting Form it is seen that the ''departure'' on line S was taken from South Pass and Pass a TOutre Lights at S*' 40" p. m. on May 9. A plotting of the bearings gives the first Definite Position, which is designated by a circle of 180 DEEP-SEA SOUNDING AND DEEDGING. one-eighth-inch radius, and marked Si. At 9^37"" p.m. bearings were again taken of the same lights, by which we get Position S2. The course and distance by dead-reckoning from Position Si to the time of Position S2 — S. t E., 5.1 miles — is represented by a dotted line. It is well to draw the line of course and distance after the manner shown — ^. e., from a Definite Position — when this can be done without producing a confusion of lines on the Tracing, but it may be laid off as shown from Posi- tion S7, or from any part of a line of position, instead of from a Definite Position on that line. The requirement is simply to make it clear between which Definite Positions, or lines of positions, the run by dead-reckoning was made. If drawn on one side, the parallel rule and the dividers will carry it up to any place where it may be needed. With a line of soundings of no very great length it is a good plan to lay down all the Sumner and other lines of position, and to mark each with its appropriate legend before plotting positions other than those obtained by bearings of objects on shore. We generally drew lines of position and Definite Position circles and symbols in red ink. From Observation I to Observation II the vessel made 1.1 knots, S. \ E., by dead-reckoning. To find the Definite Position on Observation II, lay off the run from any part of Observation I, and frorn the lower extrem- ity of the line thus projected draw another line parallel to Observation I, which will intersect Observation II in the position sought — that is, Posi- tion S4. When referring to the plotting the term " observation " will, for brevity and convenience, often be used instead of " line of position " or " Sumner -line." From Position S^ lay back the run made, by dead-reckoning, between Observation I and Observation II; the line representing the run will cut Observation I in Position S3; or carry back Observation II, by course and distance, to an intersection with Observation I. In getting Position S3 and Position S4 no current nor drift was allowed for in the run. A line drawn from the point A — the dead-reckoning position at the time of Observation I — to Position S3, would represent the current or drift from the time the vessel was at Position S2 to the time of Observation I — S. E. I E., 2.4 miles in the elapsed time of ^^ 4"", a velocity per hour of 0.8 mile. From NAVIGATION AND RECORDS. 181 this it seems plain that the Positions S3 and S^ need not be revised to allow for current, since Observation II was taken only six minutes after Observation I. It is seldom tliat any deafl-reckoiiing current need be allowed in suoli short runs between observations. What from custom is here styled cm-rent, is evidently sometimes ver^' different from the true current, and results from current, headwaj-, and sternboard during soundings, imiierfect steerage; and leeway, if it has not been allowed for in correcting the courses. During the operation of sounding a vessel is so constantly n to keep the wire vertical that no accurate run can be kept of her drift over the ground on such occasions. Since the stoppages vai-y in time — because the soundings vary in depth, and from other circumstances — the dead-reck- oning current between two widely-separated positions — as Si and S3 — does not, by any means, always give a measure of the drift at each intermediate point; hence it would be of no avail in jjlotting to strive tor a 45"' the drift was 2.5 miles, how much was it in 2'" 40™ ? The dotted line a h on the diagTam represents the drift sought, which by computation is 1.04 miles. Before seeking a Definite Position on Observation VII, Position Si should be determined. Observations X and XII were taken only 20™ apart, during which interval the vessel was engaged in sounding and manoeuvring. From this it appears that we can do no better than to locate Position Sio at the intersection of Observations X, XI, and XII. The Sumner-lines corresponding to Observations VIII and IX, which were originally accepted, have been purposely shifted 4' in longitude to the eastward, that they may be found unfit for acceptance, and so give an opportunity to show in what manner rejected observations are treated in the record, or, perhaps more strictly, how the records are amended for rejected observations. Position Sg on Observation VII is obtained by running the course 184 DEEP-SEA SOUNDING AND DEEDGING. and distance forward from Definite Position Sg and back from Definite Position Sio for a dead-reckoning latitude, after the manner of proceeding in the case of Position S?. If, instead of getting Position Sg by the method just stated, the noon observation and the evening twilight observations were to be carried to intersections with Observations VII, the several points of intersection would be as follows : By Observations VI at J, and by Observations X, XI, and XII at K, L, and M, respectively. The lines of position of Observations X and XI, making only the small angle of 18*^ with the line of position of Observation VII, give untrustworthy results, but that of Observation XII, making an angle of 42°, would give a a tolerably good position if coupled with Observation VI. It is well to take plenty of time for consideration when plotting, and to make a practice of running courses and distances forward and back, and of carrying the lines of position to intersections by various combinations, as a means of detecting those observations which, through one cause or another, are least worthy of acceptance. The position where the course was changed between Sg and S^o should now be found, the successive positions connected by right lines, and the winds and currents along the whole line of soundings ascertained and designated by arrows. Then the Plotting Form should be completed in every particular; after which it may be laid aside and the General Record Form taken up for the purpose of plotting the soundings. Unless the independent points where courses were changed are known, it would not be possible to plot the soundings correctly. While these points are deter- mined and specially marked to serve a necessary purpose, they are not classed with the Definite Positions, so called, because they do not occur on any astronomical line of position nor on any line of bearing of a shore object. It might be convenient to call them Secondary Positions. DETAILS OF THE PLOTTING OF LINE S (CONTINUED). Plotting the sotinaings.— AW the souudlugs takcu betwceu any two suc- cessive Definite Positions are generally plotted on a right line connecting those positions, but if an unusually prolonged delay has been made at any cast, making it evident that an exceptional allowance for drift or current should be applied in that instance, then it may not be practicable to adhere to the right-line method, and the case becomes one of special judgment, dependent on circumstances. When such cases arise, it should be remem- bered that, the method by right lines being the one usually followed, all NAVIGATION AND EECOEDS. 185 deviations therefrom should be specially mentioned in the column of ''remarks'' on the Plotting Form, to be transcribed to the proper Naviga- tion Forms. It is desirable that the navigation record should not be encumbered by such supplementary remarks, and they may often be avoided by taking observations at short intervals along the line of sound- ings, especially at different times during the long stoppages. When work- ing over gentle slopes like the Great Florida Bank, where for more than one hundred miles seaward the water is of less depth than one hundred fathoms, greater exactness is called for than is absolutely required in the deep basin beyond, as it is probable that navigators at large will turn to good account the soundings shown on their charts within the curve of one hundred fathoms. Line S, part of which has just been plotted, crossed very strong currents as we approached the Yucatan Bank, and on line T, run soon after from Alacran Reef to Tortugas, we experienced on leaving the Bank such a strong head wind and heavy sea, and such a swift current setting up through the Yucatan Channel, that the dead-reckoning current was five miles per hour at right angles to the direction of the line of soundings. On each of these lines we had, as a result of our astronomical observations (thirty-eight observations on Line S and sixty on Line T), as many Definite Positions as there were soundings, although the position by observation was not always that of a sounding. The right-line method was followed in plotting, but with so many Definite Positions the location of the soundings on our Sheets cannot be much in error, notwithstanding the rapid drifting of the vessel. Fig. 3, Plate 35, illustrates the plotting of the soundings between Positions S2 and S3. Sounding 2 (one hundred and twenty -seven fathoms) was taken after a run, by patent-log, of 4.9 miles from Position S2, and Sounding 3 (three hundred and eighty-six fathoms) after a run of 10.3 miles from Sounding 2, or of 15.2 miles from Position S2. In the present case these intervals might be laid off on the dotted line repre- senting the run from S2 to S3, and thence might be carried to the line proper, but frequently the line of the course and the line of soundings coincide so nearly in direction that other means must be adopted, and the manner of working may be as follows : Draw at any convenient angle with 186 DEEP-3EA SOUFDING AND DEEDGmG. the line of soundings a right Hne S2 P, equal to the distance by patent-log from Position S2 to Position S3 — equal to S2 A, or 16.2 miles. Lay off on the right line S2 P the sounding -intervals S2 N (4.9 miles), and N (10. 3 miles), as given by the patent-log readings on the General Record Form. From the points N and draw parallels to the right line S3 P, intersecting the right line connecting the Positions S2 and S3. The points of intersection are the positions to be assigned to the respective soundings. The right line S2 P may be drawn at discretion, but the method of obtain- ing the most convenient angle possible is shown by Fig. 3. From Position S2 as a center, with a radius equal to S2 A, describe the arc of a circle as shown. From Position S3 draw a tangent, to the circle. The right line S2 P, touching the circle at the point of contact with the tangent, gives the best angle that can be obtained. There are other ways of plotting the soundings on right lines joining positions, but they need not be explained here. When a change of the course is marked between two Definite Posi- tions, the soundings are plotted from the first position to the change of the course, and then from the latter to the second position. REMARKS AND SUGGESTIONS ON PLOTTING AND NAVIGATION. If the sun pass the meridian near the zenith, equal altitudes of that body give a quick and trustworthy means of finding the longitude for noon; but the conditions which are favorable for that method also greatly increase the value of the Sumner-line of position for the same purpose. Although the advantage of easy computation is on the side of the equal altitudes, it is more than probable that on the arrival of the time which would be selected to take the ante-meridian observations of the set there will have been already computed, for positions intermediate between twi- light and noon, two or more Sumner-lines, which, with scarcely any addi- tional labor, may be carried forward to be considered in connection with the afternoon Sumner-lines for finding the noon longitude. When we observed equal altitudes on board the "Blake" it was chiefly for securing a check, or for providing a substitute in case of the loss of the usual fore- NAVIGATION AND EECORDS. 187 noon observations, or to insure a noon longitude against the failure of the afternoon Sumners. The cases shown on Fig. 1, Plate 35, of getting the daylight positions— S;, S„ and Sg— are of a simple character. Were it advisable in this chap- ter to discuss the management of Sumner-lines in general, a different line of soundings would be chosen for illustration — one that would involve some perplexities in the plotting work. The mode of finding the Definite Positions on the forenoon and afternoon Sumner-lines changes with the conditions, even when the data is complete. Thus in the cases already plotted the lati- tude at the time of observation was most in doubt, but had the latitude of the vessel and the declination of the sun been widely different it might have been that the longitude was' least well defined by the Sumner-lines in point, and this would probably have caused us to arrive at the Definite Positions by other steps. It sometimes happens, when the same course has been held between a twilight and a noon position, that a right line connecting these two positions will intersect the forenoon or afternoon Sumner-lines in the most rational points for the position of the vessel on those Sumner-lines at the respective times of observation. This is the easiest of all cases for solution. When there has been hazy or cloudy weather the difficulty in the plotting work which follows is greatly increased. . On one occasion three days were spent by me in determining a single Definite Position on a line of soundings that had been run in a heavy sea with a dim horizon. This was troublesome, but in the end there was satisfaction in feeling that my conclusions were sound. The troubles are not confined to the fore- noon and afternoon positions only, but may arise anywhere. On occasions there are no forenoon or no afternoon observations, or perhaps both sets are missing; at other times the meridian altitude has failed, or morning, evening, or all twilight observations likewise; and, again, some observa- tions are presumably much more trustworthy than others, calling for care- ful comparison and discrimination in plotting. The way out of difficulties in plotting, as I have stated before, is to seek for current or drift, or dis- crepancy, by working runs forward and backward, by one disposition or another, until the errors of observation become apparent. There are a number of methods of taking a departure on a line of sound- 188 DEEP-SEA SOUNDING AND DEEDGING. ings. The best, doubtless, is that of measuring with sextants, from the ves- sel, the angular distance between three established objects on shore. Two objects in range with their angle at the vessel from a third object gives a fine position. A good way — for want of a better — is to begin the line of soundings at the outer bar-buoy or sea-buoy if leaving a harbor or road- stead. Cross compass-bearings on two land objects are almost always Avorthy of acceptance when the vessel is quiet; but with us, when they were taken in a rough sea or heavy swell, we could seldom get good results from them — /. e., when the bearings were projected on a chart the hydrography of which had been executed by the most approved methods of inshore work, they would not always intersect in the depth found by an actual sounding taken at the time of observation. Such a dilemma may possi- bly be escaped by getting a compass-bearing of one of the objects and a sextant angle between the two. When this does not succeed, and there is at hand a trustworthy chart of the place, showing the slope of the bottom to be regular and tolerably steep, a compass-bearing of only one shore object — several times repeated to make sure — may be projected on the chart and the position of the vessel marked where the line of bearing cuts a depth corresponding to the sounding taken at the time of observation. When admissible, the most suitable line of bearing on which to place the vessel for this purpose would, doubtless, be one taking a direction normal to the curves of equal depths. Sometimes we were compelled to take a departure from an isolated light-house, or other object, where the circumstances were such that to accept a position by one bearing and a sounding was out of the question. In such cases we generally managed to approach the object so as to get the possible advantage of what is known as the bow and beam-bearing problem. With the vessel steadied on her course, a bearing was taken of the landmark when it bore four points on the bow and another when it was abeam, holding the same course between, and reading the patent-log at each bearing. When there was no current the distance from the landmark at the second bearing was equal to the distance run between the two bearings. If the existence of current was suspected, then, at the second bearing, an observation was made by means of floats from a boat anchored to the sounding-rope. Any current thus found was applied NAVIGATION xiND EECORDS. 189 to the run, and if it proved to have been at an angle with the course steered the character of the problem was changed, and the case was solved by- projection on the Sounding-Sheet in accordance with the data. A check on the above is to leave a buoy at the spot where the second bearing w^as taken, and then, continuing the same course, to get a third bearing and a patent-log reading when the object bears four points on the quarter. By returning to the buoy a departure may be taken at pleasure. Methods that are adapted to taking a departure on a line of sound- ings are alike suited to closing the inshore end of a line. Changing the course between observations should be avoided as much as possible when on the lines, that the plotting work may not be complicated. Very often at evening twilight it is known that no more observations will be obtained until morning twilight, and that a course must be shaped for all night. We learned, after a few severe disappointments in the strong surface flow of some parts of the Gulf of Mexico, to shape the course for the night directly along the projected line of soundings, unless quite sure that W' e could predict the general direction and approximate velocity of the current. It was very unpleasant to find by the morning twilight position that the course had helped the current to carry the vessel aw^ay from her line. AVhile five miles of deflection might not give great concern, ten miles in the same case might be thought to detract very seriously from the appearance or the adequacy of the work. For positions we placed our dependence chiefly on the twilight obser- vations, as giving us, practically, the latitude and the longitude at the same time. A twilight horizon is, in general, a very fine one, the bright sky beyond throwing, it out black and distinct, thus offering the best of condi- tions for accurate contact in measuring altitudes at sea. To get fine inter- sections like that given by Observations X, XI, and XII (Fig. 1, Plate 35), was by no means an unusual occurrence with our navigators. By always knowing in advance the names, approximate bearings, and altitudes of the stars that each wished to observe, our navigators never lost opportunities when the time for observing had arrived. Since with Sum- ner's Method the line of position is always at right angles to the line of true bearing of the body observed, the angles which the several lines of 190 DEEP-SEA SOUNDING AND DEEDGING. position would make with each other could be foretold at once from the compass-bearings of the objects at the time of observation; hence, in select- ing the planets or stars for our purpose a due regard was had to their rela- tive bearings. Eight points evidently gives the perfect intersection, while one of two points is hardly acceptable for good work. When there was so little clear sky at twilight that the constellations were indistinguishable, the altitude of the first bright star that presented itself favorably was turned to account, for with the altitude, and the bearing that we habitually took simultaneously therewith, a reference to our handy little celestial globe rarely failed to give us the name of the star. While a globe was not exactly a necessity, hardly a day passed at sea that it was not put to good use for instruction or amusement. We did not often attach para- mount importance to meridian altitudes of stars at twilight, for, in the time given up to watching for the culmination, opportunities for fine altitudes for Sumner-lines might have escaped notice, and the advantage of observ- ing at the very best phase of the twilight horizon might have been lost to us. The records of the "Blake" show nevertheless that a large number of meridian altitudes of stars were taken during the period covering the whole work, thereby proving that we were not neglectful of them when they served our purpose best. Whenever an observation is needed and can be secured, the navigators should be cautious about deferring it in anticipation of a better chance, for the prospective chance may come to nothing, and they will then have only regrets instead of "salted" observations, as we called those taken for pre- caution. Occasionally, good altitudes of stars or planets may be had on moonlight nights — at times when the moon is not too high — by observing such bodies as will come to a contact just at the limit of the illuminated portion of the horizon. Such opportunities should not be neglected, especially when by embracing them any good purpose may be served, because it is often the case that a sky which has been clear all night becomes temporarily overcast toward the break of day. Our old hands were always alive to these points, and the new-comer quickly worked his own cure, for he was sure to find that diligence in observing lessened the perplexities of plotting. NAVIGATION AND EECOEDS. 191 AVlien the navigators were' in danger of being overworked, we found it a good plan on moonlight nights to leave with the officer of the deck a memorandum showing the watch-time of the meridian-passage of the moon or of some of the stars or planets. If the officer of the deck succeeded during the night in getting any meridian or other altitudes they were com- puted by the navigators on the day following. If the weather became overcast or foggy at a time when further prog- ress on the line of soundings without observations was thought to be a serious disadvantage, we would, when working in water less than two hundred fathoms in depth, plant a buoy, or anchor the vessel, and await clearing weather. By anchoring at intervals, we once executed success- fully a line of considerable length, the whole of which would otherwise have been lost. SECTIONS AND TEMPERATURE CURVES. Forms 14 and 15 are given as specimens of what may probably be considered the most important graphic methods of arranging for study the data obtained at the observations for serial temperatures, while Form 15 serves at the same time for presenting in a simple and comprehensive manner other useful information. Our instructions did not require us to submit anything of this kind to the office, but after our first season in .the Gulf of Mexico we began to add Form 15 to our records, and in time a continuance of the practice was expected of us. Form 14 never formed part of our records; it is chiefly because of its special importance to a party when actually engaged in the work that it is given here. Form 14.— With a plece of cross-section paper at hand, the curve may be constructed from the data in a few minutes. The horizontal or upper scale represents degrees of temperature, and the vertical or side scale fathoms of depth. The point corresponding to any depth of a series is plotted at the intersection of the vertical and the horizontal lines repre- senting, respectively, the temperature and the depth. The successive points are then connected by right lines, or all the points may be embraced in a consistent curve. This Form may be made to exhibit the relation between depth and 192 DEEP-SEA SOUNDING AND DEEDGING. temperature for a single station or for a number of stations. In the lat- ter case, the results obtained at the several stations may be compared. The gradients of a curve, by showing the rate of change in temperature between successive points of observation, give evidence of the existence of currents; but if any gradient show an abrupt divergence from the general aspect of the curve it may be found that this results from an instrumental error, and thus a curve will point out the necessity for a repetition of an observation. The heavy vertical line represents the temperature of 392° Fahr., the lowest temperature of the deep waters of the Gulf of Mexico, and that which we always found there below a depth of six or seven hundred fathoms. Form 15, — It is usual to make sections of this kind on profile paper, which gives a clear exhibit of the lines, but cross-section paper being more convenient in our special case was always used by us. The scales are arbitrary, that at the top representing miles and that at the side fathoms. The depth is generally so small in proportion to the distance run that it is necessary to greatly exaggerate the former in order to present the data-in a shape available for inspection. The data was plotted on Form 15 as follows : From the position of .each sounding on the Sounding-Sheet (Fig. 2, Plate 35) a perpendicular was drawn to a right line connecting the positions of the first and the last sounding on the Sheet. The several distances of the new or projected positions from the first sounding of the series were then set off on the scale of miles on Form 15, and, from the corresponding elements of depth and distance, the curve or profile of the bottom was constructed as shown. The further construction of the lines shown on the Form is so apparent as hardly to need special description. In drawing the lines of equal tempera- ture it was our practice to first join such points on adjacent lines of descent as were shown, by actual observation, to have equal temperatures. The figures on the line representing the surface of the water denote temperature of the surface water. ABBREVIATIOXS OF BOTTOMS. 'or Mud. bk. for black. Iird. fur hard. WEATHER SYMBOLS. )4' 35". UNG. , 1876. SYMBOLS FOB STATE OF SEA. SYMBOLS FOR APPEARANCES OF CLOUDS. Cir , Cirrui, Frinum/furm Oir Cum Cirro Ounmlui Secondur;) for Vir Str, CtnoStrUu^ Cum , Oumulus Primury furn Cum Sir. Ou) lull *( dti^ Secomhmj fu, occupied ■ounding. •mpass course I rom last sound- j South -. South _. . South . South S.byE.iE.. S.iE 3. by E. i E-. - S. IE DISTAJfCES. Initials of officer of the deck. \V. 0. S. W. 0. S. W. 0. S. W.E.S W. 0. S ■nnnected with affecting the Set watch ahead O" at nc STATISTICS OF THE LINE. Form 3. U. H. COAST S UR VEY. Off-Shore Soundings, Gulf of Mexico. GENERAL RECORD. LINE S, FBOM near South Pass, Mississippi River. TO..... latitude 26° 58' 25", longitude IN STEAMER "Blake," Lieutenant-Commander C. D. Sigsbee, U. S. N.. Assistant C. S., COMM. : BEG UN AT H HO URs 40 MINs. p.m., LATE May 9th, 1876. ENLEL A T 7 NO /,7,'s i'4 uMINs. p. m., LA TE May 89° 04' 35". 'AN LING. 10th, 1876. IS FOB APPEiKASQES 01 DATE. nil \nl \ 1,1 \( Jir ttmpera- '""T;rs)."-" (ra<«- &„«■(;„. turrenU olm zed will jloaU, Iia,anet<^ Tr/JVD Slate of the umlhe by BynhoU i Stale of \llie«at Jvcof i3- COURSES. ^f inn tolUm. l"''t Jath- '''Bz:- '''■::!::: :LnL:::::' _ ..... \ -- # Tu. '•"' S "i"»f ■' ^ .... .., J?o™, of b/symlob. ^r:/ ■"?■ '"!,'"'■ """■ 'li ' I.mgiludc. n ,y,ntoh " .. " . Maj9 M»y 9- 1„ 02 : ;; u !«(. Clmngert the W Ul 40 m 02 35 -0 Surface. j[ i;E ji — ,0, " .V ' cu. ......... .. « « ., aiK :: r w.o.s. "-::.x:-;.:,;;v-;, .-.>•..- :: : :: III :;:::::: :; ii Surfaco. 1 3»'j is 681 ;;;;;;;; J;S S ::: ™ ; ^- ' :: J 10 j : ..,,,,,,,.,,..,.,„,„ C„„, ......... M»J- >0- Mb.v 10 ----- 1.0.0 ,2 :■:■::::::::: n Cir.Cim May 10. ...._ -[*'"'" "■'^ '»- - ''"I'^^^'harolV ' ™ ;----- 1.02CZ :: s. iV" May 10 C„„ .......... 1 May 10 1.02C8 :: ' ^_ ^ " _'___ P - _^ ^ __^ T^i JL " ^ a » 1 " " • T I numhrr of nd of hoitoin fathon proh,ibh ill lays ; REMARKS. iccidijifs, losses, failures of gear or •lis to work satisfactorily, giving " ninsi's; give reason for unusual mention, generally, matters of im- K or ivteres't conmr'tcd with the work. 648 676 hud not been adjusted. 1077 1195 1313 Form 4. • V. S. COAST SURVEY. Off-Shore Soundings, Gulf of Mexico, SUPPLEMENTARY RECORD. LINE S, FROM near South Pass, Mississippi River. TO... latitude 26° 58' 25", longitude 89° 04' 35". TW KTEAMEn "B'ok-"L-U + — tC— ^- ^ D S-""He U ^ ^^ iS-'-'a"* C S r,r,.r.,r ., .r-,.j^rr, BLGV^ LI 8II0URs40 l/7Ab [ r BAIL Ma> 9tl 18/6 IMJllJ U I[0URs24: ¥/> i I 111 \\ 1 II IS C «3 U (25 D s) 194 DEEP-SEA SOUNDING AND DEEDGING. FORM -' Oompass-bearing Ship's head Patent-log Obs'n at sounding No. Obs'n shortly before sound'g Obs'n shortly after sound's ^ a between sound'gs Nos. Index correction REMARKS. H. M. S. Ths. ' Object... Horizon _ CARLILE P. PATTERSON, Superintendent. Section , OBSERVATIONS. GENERAL LOCALITY : Bough Boole of Observations No. From , 18 , Line To , 18 , Line Vessel., _-.. Chief Com' da Hyd. Party: 195 FORM (>. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. (Bearings of objects on shore.) Line from Lat. "29° 01' 40", Long. 89^ 02' 35". rn Lat. 26° 58' 25", Long. 89° 04' 35 . Coast Survey Str. "Blake," Lieutenant -Commander C. D. Sigsbee, XT. S. N., Co.MttANDi.vG. Date. May 9th, 1876, j; f^ ^o. of Positjon. 1 & 2. No. of Observation. Bearings. Line Letter. S. At Sb 40"' P. M., May 9th, touk our departure on Line S. South Pass Light, Missi.ssippi Kiver, bearing (correct magnetic), W. S.W. i W. Pass a rOutre " " '■ - ■■ '• N. | W. Patent-log, : Sonnding No. 1. DEFINITE POSITION BY ABOVE BEARINGS : Latitude. 29° 01' 40". Longitude. 89° 02' 35". Position 1. U 9'' 37" P. M., May 9th, took following bearings: South Pass Light, Mississippi Elver (correct magnetic), N.W. by W. i \V. Passal'Outre " '■ '• " " N. i W. 'atent-log, 5.1; Between soundings Nos. 1 and 2. DEFINITE POSITION BY ABOVE BEARINGS : Latitude. 28° 56' 20". Longitude, 89° 0»' 15". Position 2. iy6 DEEP-SEA SOUNDING AND DEEDGING. EEMABE8—{ Continued ). OBSERVER.^ COMPUTER.. .Lieut. J. E. Pillsbury, U. S. N. TIMES. ALTITUDES. CHRO. COMP. REMARKS. c. ■ w. c—w. a a \ a 1 w. G—W. 1 a a 197 FORM 7. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. SVMXEMfS METHOD BY .llOOX. PI.AXET (■ ), STAR (Altair). Lt.ve from Lat. -29° 01' 40". Loxg. 89° 02' 35". to Lat. 26° 58' 25". Losg. 89° 04' 35". Coast Subtey Sth. •'Blake,'' Lieutenant -Commander C. D. Sigsbee, U. S. N.. Commaxdixg. Date. May lOtli. 187(i. ^'^"•^^° 'j1;][; Xn. of Position, 3. No. of OB.sBJiv.iTJo.y. 1, Lj-we Letter, S. S.D. AUG. I.e. DIP. RBF. M COB. OBS.ALT. 2d COS. - 1 50 C. F. 4 03 C. C. 12-30-11.4 DEC. (+) COR. DEC. P.D. t 32 2'f..l M. J) ': COR .J?.^. i9-^--45.6 M. D^ lS-37-18.9 + 1-19.4 90° 00' 00" 1! \\COR + 81 27 40 :' 1 R.A.M.S. ---— — .rnn\r DIP— BY ANGLE i WITH SEXTANT. 32 oT 29 1 R. A. M. S. .105 : 180° 00' 00" For SECONDS. 3 Z. D. 3-13-37.474 LOC.iL. OIFF. \ iDIFF.= 11 •°^^- T. ALT. P.D. SVM. i S13I. T. ALT. HEM. H.A. M.A. Ji.A.MEB. E.A.M..S. L. M. T. G. M. T. LONG. T. LONG. A. 28 20 00 L.SEC. 81 27 40 L. COSEC. T UT o - // ' .'00484 9.50189 9. 79554 HOB. PAR. TAB. XIX. smr. CONST. 2d COR. .0.5542 .00484 9. 50565 LAT. P. D. 28 40 00 81 27 40 L. SEC. L. COSEC. L. COS. 71 18 54 L. COS. smi. i SUM. 142 57 48 59' 4S" 9.79395 REM. 1 ' H. A. "; 28 46 L. SIN. 38 38 46 1 i _ 3-48-30 1 . SIN. 8-43.7 /,. SI.X. i. 19. 35986 9. 67993 •S 1 19.35906 .SIN.h 9.67953 CHARACTER OF OBSERV'N. 19^4-45.6 R. A. ] if. .4. MER. R.A.M.S. L. M. T. 1 LONG. T. 9-44-45.6 Ver,/ good. Mod'Vli/ good. Barely uccept- 3-13-37.5 12-42-24.4 3-13-37.5 2-42-38.1 1 OBJECT. X 5-56-13.9 89° 03 '28" WEST. 5-56-00.2 VEST. ■ YALl-E OF 1 0-BS'i^-l DEFINITE POSITION ON THE ABOVE LINE AT THE TIME OF OBSERVATION: Latitude 28° 38' 35" Nomtb. Loxgitvde 89" 00 15" West. Patent-Log 21.35. Carried Observation 2 back, by cm with Observation 1, for Definite Position on Observation 1. [OVER.] 198 DEEP-SEA SOUNDING AND DREDGING. BE MARKS— { Continued). OBSERVER Robert G. Peck, Master, U. S. Navy. COMPUTER same. PRELIMINARY WORE. TIME AS PER SOUNDING-SHEET 12h 41'" A. M. P. M. TIMES. ALTITUDES. CHRO. COMPS. HEM J RES. 12-37-13 48 38-27 41-10 3°2 314S 58 oO 14 10 26 00 r—w. CO. a w. o-ir. c. c. OBJECT HORIZON _ —mod. good. COMP. BEARING OF OBJECT...,. SHIP'S HEAD. S'l & E^i. 21.35. Taken (hiring Sounding Na. Taken shortly before Sounding No. Taken between Soundings Nos. 3&4. 80 402 20 12-39-11.4 32 57 29 199 FORM 8. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. SUJIXER'S METHOn BY MOON, JPLAXET ( ), STAR (Vega). ™o.u Lat. -29° 01' 40". LuxG. 89° 02' 35". ro L.iT. 2iP 5«' 25" Lo.xg. 89° 04' 35". r SmvEY Sth. "Blake," Lieutenant - Coimuaiider C. D. Sigsbee, T'. S. N., Co.vjirA.wiNO. ;, May 10th, 1876, ^-" *''° pfj .\o. of Pu.-^-//;,^ 3-13-38.46 i DIFF.^ ; DIP. T.ALT. LAT. P.D. SU3I. i 8VM. T.ALT. BE3I. H.A. B.A. B.A.MER. B.A.3I.S. L. M. T G. M. T. LONG. T. LONG. A. 57 22 17 51 20 11 L. SEC. L. SIN. .05542 . 10744 9. .56368 9. 28638 LA'i: P.D. Sim. i SU3I. T.ALT. H.A. B.A. B.A.MEB. B.A.M.S. L. 31. T. G. 31. T. LONG. T. LONG. A. 57 22 17 L. SEC. L.roSEf. HOB. PAB. .05679 'I'AB.XIX. . 10744 9.29274 M COB. 137 02 28 68 41 14 00' la" 11 08 57 2-29-46. 3 11 18 57 L.SIN.i. WEST. 19.01292 9.50646 18-32-46.2 L. SIN. i. 9.01743 CHARACTER OF OBSERV'N. Very good. Mod't'y good. Barely accept- able. 16-02-59. 9 3-13-38. 5 16-02-11.2 3-1,1-38. 5 12-49-21.4 18-44-40.3 12-48-32. 7 18-44-40. 3 OBJECT. HORIZON. VALVE OF OBFN. i-'^ 5-55-18.9 88° 49' 43" 5-56-07.6 DEFINITE POSITION ON THE ABOVE LINE AT THE TIME OF OBSERVATION: Latitude 28° 37' 25" Nortit. Longitude 89° 00' 10" West. REMARKS. Rati ._22.4. l,byc< le and distance, tc nth. Observation 2, for Definite Position on 200 DEEP-SEA SOUNDING AND DREDGING. BEMABK8 — ( Continued). OBSERVER ., Robert G. Peck, Master, U. S. Navy. COMPUTER same. PRELIMINARY WORK. TIME AS PER SOUNDING-SHEET 12» 47™ A. M. P. M. TIMES. ALTITUDES. CHRO. COMPS. REMARKS. 45-08 47 - 23 °7 ,14 30 T,i,„I .-,,n(l_ 14 lU 21 00 27 30 . 44 30 C—W. CO. a G—W. 0.0. HOmZON " " 1 .....A SHIP'S HEAD. Trden diirimj Sounding 17u. 'J'uken shortly after Sounding No. Talcen between Soundings Nos 3 & 4. 02 201 20 12-4-1-13.1 57 28 46 FOEM !). [On this form the Italics show 201 iresented by Eomaii.] 1 matter uf the blank form, while the written or recorded m FORM 9. U. S. COAST SURREY. OFF-SHORE WORK. GULF OF MEXICO. SUMNER'S METMOn BY MOOX, PTjAXET {S:iUu-n), STAR ( >. Li.wE FROM L.a: 29° 01' 40", Lo.xg. 89° 02' 35", to L.xt. 2fio 58' 25", Lo.wa. 89° 04' 35". Co.isT SuHYEY Str. "Blake," Lieutenant - Uommander C. D. Sigsbee, U. S. N;, CoMM.iyniKa. Dat g.Mav 10th. 1876. ^^^°"j!;j;^:J\ ^0. OP POSITIO ',5. No. OF Observation, 3. Line Letter s. S.D. AUG. I. a DIP. REF. M COR. OBS.ALT. 2d COR. - 1 50 720 W.T. C-W. C.F. G. M. T. G.D. 4-23-1g!5 5-58-09.2 DEG.{-) i COR. ' COR. DEC. + 4.6 M.D. — 2.9 y.R.A. ~^-^ \\COR. 2°2 36 46^56 — .94 ilf..D. + .583 —.162 583 9-21-25.7 + 1-19.3 10 23 45 90° 00' 00" 4.0 COR.R.A. 22-36-45'.G2 22-22-45 P.D. 100 23 45 .944 9^ + R. A. M. S. Cor. G. M. T. B. A. M. S. 3-14-30.27 — 15.935 — .041 For G. 31. NO ON. FOR H. & M. For SECONDS. LOCAL. DIP— BY ANGLE WITr\ SEXTANT. 1 32 43 45 $Z.D. BOR. DIFF. \DIFF.^ DIP. 180° 00' 00" 3-14-14.3 T. ALT. LAT. P.D. SUM. iSUM. T. ALT. REM. H.A. R.A. R.A.MER. r'.a. M. S. L. M. T. G. M. T. LONG. T. LONG. A. 3°2 3'6 25 2S 00 00 100 23 45 L.SBC. L.COSEC. L. COS. L.SIN. . 05407 .00718 9.21755 9. 87035 T. ALT. LAT. P. D. STJM. iSVM. T. ALT. REM. U. A. R.A. R. A. MER. R.A.M. S. L. M. T. G. M. T. LONG. T. LONG. A. 32 3^ ik 28 20 00 100 23 45 L. SEC. L. COSEC. L. COS. L. SIN. .05542 .00718 9. 87149 SOR PAR TAB. XIX. SV3I. CONST. 2d COR. 161 00 10 80 30 05 161 20 10 80 40 05 59' 1,2" 47 53 40 2-5°6-25.7 22-36-45.6 h. m. a. 2-55-20 L. SIN. i. WEST. 19.14915- 9. .57457 L.SIN.i. WEST. 19. 14402 9.57201 CBABACTEB OF OBSEBV'N. 1 1 I 1 p s 19-40-19.9 3-14-14.3 22-22-45.0 19-41-25.6 3-14-14.3 16-27-11.3 OBJECT. HORIZON. VALVE OF OBS'N. X X 5-56-39.4 89° 09-51" 5-55-33.7 88° 53' 25" DEFINITE POSITION ON THE ABOVE LINE AT THE TIME OF OBSERVATION : L.iTiTUDE 28° 14' 15" North. Longitude 88" 5803" West. Patent-Log, 44.6. Carried Observation 4 back, by cc with Observation 3, for Definite Positi 202 DEEP-SEA SOUNDING Ai^D DEEDGING. BUMAEKS— {Continued). OBSERVER Robert G. Peck, Master, U. S. Navy. COMPUTER same. PRELIMINARY WORE. TIME AS PER SOUNDING-SHEET 4I' 25'" A. M. P. M. TIMES. ALTITUDES. CHRO. COMPS. REMARKS. 4-22-56 23 -37 3°2 40 10 V. a c. w. c—w. a a OBJECT - - - HOBIZON —mod. good. 33 87 30 SHIP'S HEAD. 44.6 5&6. 4-23-16.5 PATENT-LOG Taken shortly he/ore Souadmg No. Taleen shortly of ter Sounding No. Taken between Soundings Nos FORM 10. 203 is foi-m the Italics show tlie printed matter of tlie bhink form, while the written or recorded matter is represented by Eon FORM 10. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. SiryrXJEH'S jftETHOJD JtY MOON, JPLAXET (Jniiiter), STAR ( ). Li.vE FROM La t. 290 or 40", Long. 89° 02' 35", ra La t. 2l50 58' 25", LoTiu. 89° 04' 35". Coast SvnvEY Stk. "Blake," Lieutenant -Commander C. D. Sigsbee, U. S. N., Commanding. Date, May 10th, 1876, ^'J^'Zjp.M. ^°- of Position, 6. No. op Ohservatiox, 4. Line Letter, S. S.B. AUG. I.e. DIP. 1st COlt OBS. ALT. M con. O W, h. m. ,,. [1 o , „ M. D. - 4.01 F- 1,. „,. ,. Jir.D.— 1.285 — 1 50 14 17 50 G-W. C.F. a a G. M. T. G.D. 4 33 10.2 |i^^...^ 1 ~ 1.45 COB ' ' ^ - -1.45 1.285 10-31-20 + 1-19.4 00° nr uo" ]'i;,l COB.B.A 15-44-13. 6 22-32-39.4 -1 IP.D. 108 40 r,\ -f5.8l!! -1-1.863 B.A. M.S. i Cor. G. M. T. " ! B.A. M.S. .3-{i-3.;:27 For G.M. NOON FOB H.AM. For SECONDS. LOCAL. DIP— BY ANGLE WPFH 1 i SEXTANT. \ 2. Z. D. HOB. DIFF. h DIFF.^ : DIP. m° 00' ofi' 3-14-15. 9 T.ALT. LAT. P.O. SUM. iSUM. T.ALT. BEM. H.A. B.A. B.A.MES. B.A. M.S. L. M. T. G. M. T. LONG. T. LONG. A. U 08 22 108 40 51 L.SEC. L. COSEC. L. COS. L. SIN. .05407 .02350 9.40123 T.ALT. LAT. P.O. SUM. iSUM. T.ALT. 14 08 22 108 40 51 L.SEC. L.COSEC. L. COS. .02350 9. 94295 HOB. PAB. TAB. XIX. SU3I. CONST. 2d COB. 75 24 36 151 09 13 75 34 36 59' 42" 61 16 14 4-07-23. 2 15^4-13.6 BEM. i 61 26 14 L. SIN. L.SIN.i. WEST. 19.42175 9.71087 _£_! ,^«-*2"^ CBARACTER OF 1 OBSERV'N. \ B.A. B.A.MEB. B. A M S. 15-44H3. 6 J...-.JiV.5.1 ». (iUB( .:ii 19-51-36.8 3-14-15. 9 1 1 l;l L. M. T. G. M. T. LONG. T. LONG. A. 16-37-20.9 22-32-39.4 16-36-27.2 22-32-39.4 OBJECT. HOBIZON. VALUE OF OBS'N. ■ X 5-55-18.5 5-56-12.2 WEST. DEFINITE POSITION ON THE ABOVE LINE AT THE TIME OF OBSERVATION: Latitude 28° 12' 25" North. Longitude 88° 58' 00" West. BEMABKS. Patent-Loo 46.4. Carried Observation 3 forward, by course and dist . 4, for Definite Position on Observation i. [OVER.] 204 DEEP-SEA SOUKBING AND DEEDGIKG. BE MARK 8— {Continued). OBSEEVER Kobert G. Peck, Master, U. S. Navy. COMPUTER same. PBELIMINABT WORK. TIME AS PER SOUNDING-SHEET 4^ 35™ A. M. P.M. TIMES. ALTITUDES. CHBO COMPS. REMARKS. 4 -31- 39 3.i-02 33-57.5 34-54 14 34 10 26 40 20 20 09 20 13 58 40 c. w. G-W. a a c. CO. OBJECT HORIZON OOMP BEARING OF OBJECT good. SHIP'S HEAD. Taken during Bounding No. TaJcen shortly before Sounding No. 51 89 10 4-33-10.2 TaJcen between Soundings Nos 205 ted by Roman.] FORM 11. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. aVMNEWS METHOD BV SUN. 'ROM Lat. 29° 01' 40", LoxG. 89° 02' 35", to Lat. 26° 58' 25", Loxa. 89° 04' 35". SuRvjn- St/i. "Blake," Lieutenant -Commander C. D. Sigsbee, II. S. N., CoMMA.vDiNa. No. OF Posmox, 7. No. of Observation, 5. Line Letter, S. S.B. PARX. I.e. REF. DIP. COR. OBS.ALT. + + + 52 15 52 06 1 50 43 4 03 9 22 45 00 IF. r. G—W. C.F. CO. G. M. T. G.D. r"' DEG.{+) COR. COR. DEC. P.D. 17 47 17 2 06 II. D. +.38.7 + 3.27 11.61 EQ.ofT. COR. COR. EQ. OFT. 0-34-7.75 n. D. + .09 +3.27 + .2943 3-15-02.5 1 19 5 17 49 23 90° 00' 00" 3-48.04 3-16-22 104 + 72 10 37 + 126.5 TALT LAT. P.D. SVM. iSUM. T. ALT. REM. L.A.T. EQ. OF T. L. M. T. G. M. T. LONG. T. LONG. A. 5°2 54 22 27 40 00 72 10 37 L.SEC. L. COSEC. L. COS. L. SIN. .0.5273 .02136 9.37212 9.60015 T.ALT. LAT. P.D. SUM. 4 smL T.ALT. REM. L.A.T. EQ. OF T. L.M. r. G. M. T. LONG. T. LONG. A. 52 54 22 28 00 00 L.SEC. L. COSEC. L. COS. L.SIN. .05407 .02136 9.3G688 9. 60305 DIP-BY ANGLE WITH SEXTANT. 2 Z. D. HOR. DIFF. i DIFF. = DIP. 180° 00' 00" 76 22 29 153 04 59 CH ABAC TEE OF OBS'N. 23 28 07 h. m. J. 9-24^07 3-48 2.3 ,38 07 9-24-18. 2 L.SIN-.h WEST. 9.04636 L.SlNi. WEST. 19.04536 1 1 ! 1 9-20-19 3-16-22 9-20-30.2 OBJECT. HORIZON. VALVE OF OBS'N. X X X 5-56-03 .89° 00' 45' 5-55-51.8 88° 57' 57" DEFINITE POSITION ON THE ABOVE LINE AT THE TIME OF OBSERVATION : Latitude, ^1° 48' 55" North. Longitude, 88° 59' 25" West. BE MARK 8. ..70.2 :e foi-Wi a from Position Se.and hack from owing for time-intervals. [OVER.] 206 DEEP-SEA SOinmiHG AKD DREDGING. REMARKS— {Continued ). OBSERVEE Roberta. Peck, Master, U. S. Navy. COMPUTER : same. PRELIMINARY WORK. TIME AS PER SOUNDING-SHEET, 9b 15"^ A. M. _ ALTITUDES. CHRO. COMPS. 3-14^39. 15-02. SUN HORIZON. COMP. BEARING OF ,STi\' _„_ SHIPS HEAD. PATENT LOG Talien during Sounding . Taken shortly before Sounding No. G-W. C.C. Talcm befioe onndings Noe. FORM 12. 207 FOKM 13. U. S. COAST SURVEY. OFF-SHORE WORK, GULF OF MEXICO. MERIItlAX ALTITUDE OF SVX, UOOX, VI.AXET ( ), STAR ( ). Like from Lat. 29° 01' 40", i-.-w;. 89- 02' 35", to i.ir. 26° 58' 25", Long. 89° 04' 35". Coast Sujivey Stu. "Blake," Lieutenant - Commander C. D. Sigsbee, U. S. N., Commaxding. ; 9. iVb. OF OasERTi FORM FOE SUN OR STAR. 6. LiiVE Lettes, S. OBS. ALT. COR. T.ALT. Z.L. DEC. LAT. 80 06 50 9 52 S.D.^ , P.17?A-. + I.C.— REV.— DIP. - COR. + 15 52 02 1 50 DEC. (+) COR. DEC. 17 47 14. G 3 48.8 H. D. + 38.6 LONGT.+ 5.93 193.0 34.7 ! 1.1 CHABACTEB OF OBS'N. ! 1 r 8U 16 42 17 51 03. 4 + 222. 8 SUN. HORIZON. VALUE OF OBS'N. X X X 9 43 IS DIP— BY ANGLE WITH SEXTANT. '2Z.D. DIFF. i DIFF. = DIP. 180° 00' 00" 27 34 21 1 ■ OBS. ALT. H.P. TAB. XIX. G. M. PASS. COR. LONG. L.M.PASS. LONG. G.M.T. M.RET. LONG. AUG. LC. REF. 2d COR. T.ALT. Z.D. 90° 00' 00" DIP. M COR. SIM. CONST. 59' 42" DEC.i ) COR. COR. DEC. M.D. DEC. i LAT. DEFINITE POSITION ON THE ABOVE PARALLEL AT THE TIME OF OBSERVATION: Latitude 27° 34' 21" North. Longitude 89° 02' 30" West. REMARKS. Patent-Log 85.4 with Observation 6. ] [OVEB.] 208 DEEP-SEA SOUNDING AND DEEDGING. EE MARK 8— (Continued). OBSERVER Eobert G. Peck, Master, U. S. Navy. COMPUTER same. REMARKS. TINE AS FEB SOUNDING-SHEET A. 31. P. 31. Noon. OBJECT __ __ . . . . rood HORIZON . ...._.. " SHIP'S HEAD. PATENT-LOG TAKEN DXmiNG SOUNDING NO. TAKEN SHOBTLT BEFOBE SOUNDING NO. TAKEN SHOBTLT AFTER SOUNDING NO. TAKEN BETWEEN SOUNDINGS NOS 9& 10 May 10- May 10- 5". a. re. Second column of remarls. (Descnhing the manner of getting ecLch position, <^-c.) May 10_.- May 10— May 10— May 10— May 10- May 10_. May 10- May 10- May 10_- Form 13 (A). U. S. COAST SURVEY. Off-Shore Soundings^ Gulf of Mexico, PLOTTING FORM. LINE S, FROM near South Pass, Mississippi River. TO latitude 26° 58' 25", longitude 89° 04' 35". IN STEAMER '-Blake," Lieutenant-Commander C. D. Sigsbee. U. S. N., Assistant C. S., COMMANBINa. REG- UN AT 8 HOURs 40 MINs. p. m.. DATE May 9th, 1876, ENDED AT 7 HOURs 24 MIM. p. m. DATE May 10th, 1876. Tirr OBSi J r itio ^' I IfM i tMlE rOSMlIO\S ""'fY,'" Itititmle /oiif/ifiuU Second column of remarks. Describing the manner of gettiny each position, tf'C.) May 10 May 10 May 10 Blay 10 May 10 te ( May loJp' May 10, -r May 10. May and distiince, to an Intersection with Oba. I (1) for Def. Pos. on Obs. I (1). I distance, to an intersection with Obs. II (2) for Def. Pos. on Obs. II (2). distance, to an intersection with Obs. Ill (3) for Def Pos. on Obs. Ill (3). nd distiince, to an intersection with Obs. IV (4) for Def Pos. ou Obs. IV (4). =■ and distance forward frou s thus found, allowing for I Pos. .Ss and back from Pos. Ss. Jl.s. VII (7) back to an i des thus found, allowing f itersi'ction with Obs. VI (6). or time-intervals. urse and distance forwar les thus found, allowing fo from Pos. Ss and back from Pos. Sio. r time-intervals. (8), XI (9), and XII (10), gives Def Pos. on Obs. X (8). 8), XI (9), and XII (10), gives Def Pos. on Obs. XI (9). (8), XI (9), and XII (10), gives Def Pos. on Obs. XII (10). Form 13 (B). U. 8. COAST SURVEY. Off-Shore Soundings, Gulf of Mexico, PLOTTING FORM. LINE 8, FROM near South Pas^i. Mississi))jii River. TO. latitude 26° 58' 25", longitude 89" 04' 35". IN STEAMER "Blake," Lieutenant-CoiumaLidci' C. D. Sigsbee, U. S. N.. Assistant C. S., COMMANDING. BEGUN AT 8 HOURs 40 MINs. p. m., HATE May 9tli, 1876, ENDED AT 7 IIOURs 24 MINs. p. m., DATE May 10th, 1876. Time <-/ and dlsan.o, >o an Into-Kti.n »Ub Ob.. 1 (1) for D.f. Pc. on Ob.. 1 (1). ■ j cari«i I f -db ^ dd 1 1 nob.iiwr II rp ob.iiw ""^ '" -- •---: "■ , ' ,£^;;s.ss^ 40.4 L ' I. , nrP 0b.n.(3, 35 i 4 ^'7 1 ^ g s. s s s? ^? 7;;: -j; ■ ' ^^' V......J V. :::..:::i ;: ::: :: :: — --- — "v:;: ■:;-:;:ii;;l'""-"""'' ! 80 05 0.-, z s s 80 01 13 10,3 r 1 |, , ,; „|.M.S.audl«krn>IIlI><».S». """"- 1 M^"" ■'"" -- ' ' "" : ■ .. ..Chan e«ft..e course- miccM: Filed io 111. Alcblvc 1 1 1 „.„,...-»! ^ , F .0.3 . .0 ,« .» «» .. .. May 10 ' sn 1 P.M. Oipollii VG \II 10 Sounding Sfn. r 1— .. *'•'■" -- ' i "'■ j •'■■'"■ Tb. lnu.™»tl„n or 0b»™u«„. S(8).X. (C.-nd X.1 ,101, irt™ B-f. P... "» Ob.. XII (10). ! 1 FORM 14. 'p#? ees of Temperature- Fohrenlieil 1 ^4^ m 1 S por 1 1 i ; -^ BS 1----Tr -jWj^ — j^ y |-l- — — r z^^zz-: i^r ^- i±i t^i^ ^^^sig^ g: =: g,o[i-}-|nT|| ^-^^ir^^^ ::S: =^- 5: ^ zHzh _J;i/:. -M/H"' ' ' p ~h — ^ — :::: i: 6^, ! i 1 1 1 71/ yi • ■ ' ' 1 '" ! ■ " ::: li 3 "''^ tFi/^ i"T^^-^--lf I- -?= = = ^"1^ =w 1 — V'ti^"' — ^^ — 1 — - 1 1 1 1 - :S :^ £" {--j -W-L '- "i ■ri}: -^ R -4-H-|ff- ^r"^ i llTt :J +T ^ 1/ i :_L ::::::+:::$:::::: ::: IZ --T — ^ M'lp ::: i: K iiji :ir -3 E? ip-^OTii :::±:: ::: " = .oo:|:: ::S — I ij: iiti :: ■ ■" "H" ::: i: I — -- ^J4[[^ #]4MFlwt :ih: ^4= asi" TEMPERATUR.E CURVES AT EACH STATION ON LINE S. OF 1875- 6., GULF OF MEXICO. SUPPLEMENT. stjf'fle:sie;?^t. rilK SIGST5EE MACHINE FOR SOUNDIXG WITH WIRK; PATTERX OF issi. During the year 1881 a Sigsbee Suundiiig-Machiiie was niatle for eacli of the following-named organizations: U. S. Navy, U. S. Coast and Geodetic Survey, and Imperial German Navy. Another is now being made for the U. S. Commission of Fish and Fisheries. The leading object in this sup- plement is to point out such improvements in these machines as are not embraced in the machine shown on Plate 8, (fcc, of the original volume lo which the supplement pertains. The references herein relate to the original volume. In the views shown on the two accompanying Plates the scale of dimensions is the same throughout the set. In the construction of the new machines metal only has been em- ployed, a cast-steel bed. in two parts, replacing the wooden bed formerly ■ used. The new style of bed allows the machine to be more compactly folded than before.^ The strain-pulley has been abandoned and its former place on the bed is now occupied by the steam-engine and a special form of tightening-pulley.'- An auxiliary brake has been placed beneath the reel: a single spur buffer only is used at the foot of the guide-pipes, and the outriggers to which the side stays are set up. and the casting which su])ports the fairleader and swivel pulley, are now hinged or pivoted.' The intention is to adapt the machine for folding with the removal of so few parts that, ui inexperienced hands, there need be no doubt as to the position Avhich each part should occupy when the machine is set up for use. Steel castings are used wherever they can l)e utilized. mp. Plate 1'2. -Page 62, M A, ami p. 7-2, H 1. 212 SUPPLEMENT. Plate 42 shows the right side of the machine. In Fig. 1 the machine is rigged for reeling in by steam, tlie reel being connected with the engine by means of a belt of round leather on one part of which rests the tight- ening-pulley.^ The swivel-pulley is down in the position it would have when reeling in while the ship has headway.- Fig. 2 shows the machine in temporary disuse, as in port, for instance. The reel, being unshipped, is supposed to be in the tank containing preservative.^ The register is thrown back out of the way.* The fairleader arrangement is thrown back on its pivot and the swivel-pulley is carried still farther to the rear on another pivot; neither are unshipped. The side stays are slacked and their outriggers are thrown up on pivots' into a snug position." The two parts of the back brace or stay are disconnected, and the upper section of the guide-pipes is thrown back where it remains supported, all parts of the machine thus being accessible for cleaning. Plate 43 shows the Icft side of the machine. In Fig. 1 it is rigged for paying "out.*" The belt is disconnected and the friction-line is applied. The swivel-pulley is laid aside, resting on the left outrigger. The clamp is in use in the fairleader as if the reel had been stopped temporarily to repair a defect in the wire,^ Fig. 2 shows the machine folded for trans- portation or stowage, the reel being in the tank. The cross-head pulley has been removed, but the cross-head itself remains in place. ^ In folding the machine the reel and this pulley are the only parts that do not remain hinged or otherwise attached to their proper places ; such bolts or screws as are necessarily removed are again replaced, after the machine has been folded, to secure them against loss or error in future adjustments. The front part of the bed has been thrown upward, carrying with it the guide- pipes. The guide-pipes are folded in a reverse way from ihat shown in Fig. 2, Plate 42, while the outriggers, fairleader arrangement, and swivel- pulley are folded as shown in that figure. For inclosing the machine when folded, a box is placed over it and screwed to the wooden piece shown by the figures of Plates 42 and 43. This wooden piece forms the ' Comp. Plates 7 ami 13. '^ Page 81, t 2. ^' Page 34, IT 5. ^Page62, 113. "Comp. Plate 12. « Page 67, H 5. • Page 77, IT 2. sPage 63, 1[ 2. r > SUPPLEMENT. 213 bottom of the box, but, for coiiveiiieiice, il is pormanently attached to the steel bed. The outside dimensions of the l)()x. when il is made of lieavy stuff, are as follows: length. 4 feet o inches; ])readlli. 1 foot S inches; heiglit, 3 feet. In tliis space are stowed such conveniences as tlie steam- engine, tigiitening-pulley, accumulator, dynamometer, governor, swivel- pulley, auxiliary brake, etc.^ The bed is well shown in the several ligiues of Plates 42 and 43. It is composed of two skeleton frames of steel, hinged together by bolts. The steel bed does away with the \varping sometimes experienced with the wooden bed when exposed to a hot sun. Warping of the bed throws the standards of the reel out of alignment, which makes the axle of the reel bind in its bearings. The enaine does uot ditfcr essentially from that shown on Plate 18, with the exception of being vertical instead of inclined.' The tigtitening.puiiey? A collar, sHdiug ou tlie Vertical shaft shown in the plates, has a stud on one side which forms the axle for the pulley. The tension on the belt is maintained by the elastic pressure of a si)iral spring. Along the shaft are bored holes at regular intervals, into any one of which the pin shown near the top of the shaft may be inserted accord- ing to the amount of pressure which it is desired the spring shall exert. When the tightening-pulley is not in use the shaft is turned on its axis, carrying the pulley to the left side of the machine, giving place for the standing part of the friction-line, or the spring scales — Fig. 2, Plate 42. and Figs. 1 and 2, Plate 43. A pin at the foot of the shaft keeps the latter from turning when it should remain immovable. Tite outriggers are oT cast-stecl; each is fastened or hinged to the bed by a bolt going through a longitudinal slot in the outrigger.^ In use the inner ends of the outriggers rest upon studs projecting from the bed. The anxiiinry hrahe and its ttse. — The brake is a lever of the first order, pivoted on a block screwed to the board shown on the plates. The end of the lower arm, which is fitted with a wedge-shaped piece of wood, may be pressed into the V-groove of the reel by force applied to the other arm, 1 Comp. p. 67, nil 2 and 3. -Page 87, H 2. ^Comp. p. 86, H 3. •'Corap. Plates 8 and 12. 214 SUPPLEMEl^T. but, in the absence of such force it is held out of action by a spring. The auxihary brake serves for immediate and temporary use in the event of the friction-hne or the connecting-belt parting, and in unusually heavy seas and under adverse circumstances it may be used in lieu of the toggle tucked into the friction-line — described in the original volume. The office of the toggle — although it is rarely used — is to impose upon the reel a small amount of friction which will not be lessened by the action of the governor,^ the object being to permit in heavy seas a rapid rate of paying out.^ The occasional advantage which may be derived from this acces- sory is well illustrated by such an extreme case as would make the use of the auxiliary brake desirable, thus: sounding from the bow; sea heavy; ship pitching violently; a heavy reel in use, and containing a large coil' of wire which adds much to its weight at the periphery.' Under these conditions, and when the reel is revolving with considerable speed, the vessel rises suddenly, increasing the tension upon the wire which is being payed out; the cross-head is borne down, easing the friction-line, we will assume, more than is desirable, and the heavy reel, thus deprived for a second of nearly all frictional control, is set revolving with great rapidity. At this instant the vessel gives a quick, deep plunge. The reaction of the accumulator acting as a governor is almost instantaneous, and the friction-line is set hard taut ; but before the momentum of the heavy reel can be overcome the wire slacks and perhaps flies from the reel. If, in the case stated, the auxiliary brake, which is independent of the governor, had been bearing upon the reel with a constant pressure, maintaining a .slight resistance, the undue slacking of the friction-line would not have been followed by such excessive' revolution of the reel. To insure an even pressure of the auxiliary brake, the inboard end of the brake-lever — the long arm — might be connected with the bed of the sound- ing-machine by a spring of rubber or metal which could be set to any desired tension. It must not be inferred that the auxiliary brake is a necessity; it is intended as a convenience on extraordinary occasions, to obviate the necessity for unusual skill or judgment on the part of those 1 Page 68, If 6. ^ Page 70, II 2. ; ■' Page 56, If 1. r > H W CO SnPPLEMENT. 215 operating the machine. It has been my purpose to add to the sounding- macliine, when wai-ranted by economy, every appliance which may save time or prevent accidont. In many localities there is but a small propor- tion of weather during which astronomical observations can be had for determining the positions of soundings; it is therefore highly imporlant in such localities to make the hest use of favorahle weather. GRAVITATING OR COLLECTING TRAP FOR OBTAINING ANIMAL SPECIMENS FROM INTER- MEDIATE DEPTHS. In the original volume, page 144, last paragraph, and page 145, foot- note, reference is made to the invention of an apparatus for collecting animal forms from intermediate depths. The apparatus has now been well tried and a full description of it by myself (accompanied by a drawing), and a statement of the results obtained, by Prof. Alexander Agassiz, is contained in the "Bulletin of the Museum of Comparative Zoology at Harvard College, Vol. VI, Nos. 8 and 9, September, 1880."' 1 quote a part of my own description contained therein, as follows: ''The old practice of dragging for animal forms at intermedia] depths by means of a tow^-net, which, during the several operations of lowering, dragging, and hauling back remained open, was not regarded by Prof. Alexander Agassiz as affording acceptable evidence of the habitat of such specimens as were obtained, and he frequently referred to the subject during our association on board the ''Blake"" in 1878. "In March, 1880, it having been arranged that Professor Agassiz should make another cruise on board the " Blake, "" Commander J. Pi. Bartlett, U. S. N!, commanding, he asked my co-operation in devising an apparatus to meet the rigid demands of the work in question. This resulted in the apparatus described herein, which is presented in the pre- cise form used with success by the "Blake,"" although, as may readily be seen, it is open to great improvement, especially in minor details. "The 'Challenger' had examined intermediate depths by means of tow-nets trailing from the dredge-rope while hauling the dredge or trawl. In such api'actice it miisl have been that the depths to which the nets 216 SUPPLEMENT. were sunk depended in some degree on the amount of slack-rope payed out, and also on the strain upon the dredge-rope due to the resistance encountered by the dredge when dragging; it cannot, therefore, be said that strictly determinate depths were examined by that method, even assuming that the nets gathered nothing while being lowered and hauled back. "It occurred to me that by using an apparatus in connection with a line and lead, payed out vertically as in sounding, and by dragging verti- cally, instead of horizontally as formerly, there would be at least as much certainty with regard to depths as in the old method, and that simple mechanical devices could be invented to satisfy the conditions of the work. The scheme has been stated in my volume on 'Deep-Sea Sounding and Dredging' (p. 145, foot-note), as follows: "'Our plan is to trap the specimens by giving to a cylinder, covered with gauze at the upper end and having a flap-valve at the lower end, a rapid vertical descent between any two depths, as may be desired; the valve during such descent to keep open, but to remain closed during the processes of lowering and hauling back with the rope. An idea of what it is intended to effect may be stated briefly thus : Specimens are to be obtained between the intermediate depths a and h — the former being the uppermost. With the apparatus in position, there is at a the cylinder suspended from a friction clami^ in such a way that the weight of the cylinder and its frame keeps the valve closed ; at I there is a friction hiffer. Everything being ready, a small weight or messenger is sent down, which on striking the clamp disengages the latter and also the cylinder, when messenger, clamp, and cylinder descend by their own weight to h, with the valve open during the passage. When the cylinder frame strikes the buffer at h the valve is thereupon closed, and it is kept closed thereafter by the weight of the messenger, clamp, and cylinder. The friction buffer, which is four inches long, may be regulated on board to give as many feet of cushioning as desired.' " The trap was first ti-ied in Narragansett Bay, and soon after was used for the second lime at sea, several improvements having been made in SUPPLli^MENT. 217 the meantime by Professor Agassiz and Commander Bartlett. I quote from the Bulletin again, this time giving Professor Agassiz's words : ''On the 1st of July the Sigsbee cylinder was tried for the second time in Lat. 39° 59' 16" N., Long. 70° 18' 3()" W., in 260 fathoms of water. The surface was carefully explored with the tow-net to see what pelagic animals and others might be found on the surface. There were found Calanus, Sagitta, Annelid larvee, Hydroid Medusae, Squillee embryos. Salpge, and a few Radiolarians. The cylinder, filled with water which had been carefully sifted through fine muslin, was then attached to the dredging-wire, and lowered, so as to collect the animals to be found between 5 and 50 fathoms. The time occupied by the cylinder in passing through that space was 28 seconds. The cylinder was then brought up. and the sieves and gauze trap carefully washed with water, which had also previously been strained through fine muslin. The water was care- fully examined, and we found the very same things which had a short time before been collected at the surface with the tow-net and the scoop- net; nothing different was collected by the cylinder. The Pvadiolarians (two genera) were perhaps more numerous than at the surface. A slight breeze having sprung up after the surface collections had been examined, the cylinder was then sent down a. second time at this same station, so adjusted as to collect any animal life to be found from a depth of 50 to 100 fathoms. Not only in this experiment, but in all the subsequent ones, the same precautions were taken in regard to straining the water which filled the cylinder at the start, as well as that used for washing out the sieve and the gauze trap. The messenger sent down to detach and open the machine occupied 21 seconds in reaching the (50 fathoms) point to which the cylinder was attached, and the cylinder then occupied 30 seconds in passing to the stop at 100 fathoms. On examining the sieves, it was found that the more common surface things, Calanus, Sagitta, Annelid larva?, Hydroid Medusae, and Squillse embryos, were entirely wanting, and there were only two Radiolarians of the same species as those from 'the upper levels found after a careful scrutiny of the water. Nothing additional was brought up. The cylinder was then sent down a third time, lowered to a depth of 100 fathoms, the messenger sent down 218 SUPPLEMENT. to open it (time occupied 45"), and the cylinder traveled from 100 to 150 fathoms (time 45"), so as to collect the animal life to be obtained between these limits. On drawing up the cylinder and washing out the sieve of the trap, not only did we find that the water contained nothing different from what had been brought up by the cylinder from the lesser depth, but it did not contain even a single Radiolanan. "On the 15th of July, in Lat. 34° 28' 25" N., Long. 75° 22' 50" W., we tried the Sigsbee cylinder for a third time, in a depth of 1,632 fathoms. With the same precautions before and after using it, the cylinder was sent to collect first between 5 and 50 fathoms (time 30"). The surface' was somewhat ruffled, and but little was found on the surface beyond a few Crustacean larvee and Heteropods. The cylinder contained Hydroids, fragments of Siphonophores, pelagic Algae, Crustacean larvae, and Hetero- pod eggs; forms which -differed from these scooped at the surface, but were identical with the species found on previous days at the surface under more favorable surface conditions of the sea. Next, the cylinder was arranged to collect between 50 and 100 fathoms (time of messenger 21" from surface to 50 fathoms, time of cylinder 40" to stopper from 50 to 100 fathoms). The water was found to contain only a couple of Squillae larvae, similar to those fished up at the surface. The third time the cylin- der went down at this station it was lowered to collect from 100 to 150 fathoms (time of messenger from surface to 100 fathoms 45", time of cylinder in passing from 100 to 150 fathoms 45") . The water when ex- amined contained nothing. No Radiolarians were found at this station, either at the surface or at any depth to which the cylinder was sent (150 fathoms) . "The above experiments appear to prove conclusively that the sur- face fauna of the sea is really limited to a comparatively narrow belt in depth, and that there is no intermediate belt, so to speak, of animal life, between those living on the bottom, or close to it. and the surface pelagic fauna. "The experiments of using the tow-net at great depths (of 500 and 1,000 fathoms), as was done by Mr. Murray on the 'Challenger,' were not conclusive, as I have already pointed out on a former occasion, while SITPrLEMENT. 219 the so-called deep-sea Siphoiiophone, taken Ironi (he souiidiiig-liiie by Dr. Studer, on the 'Gazelle," may have come, as 1 have so often observed ill the Caribbean, from any depth. I do not mean, of coarse, to deny that there are deep-sea Medusee. The habit common to so many of our Acalephs (Tima, ^Equorea, Ptychogena, etc.) of swimmiiig near the bottom is well known; Dactylometra moves near the bottom, and Polyclonia remains during the day turned up, with the disk downward, on the mud bottom. I only wish to call attention to the uncertain methods adopted for ascertaining at what depth they live. "As far as the pelagic fauna is concerned, those who have been in the habit of collecting surface animals know full well that the least ripple will send them below the reach of commotion; Muller and Baur were the first to adopt the use of a tow-net sunk below the surface to collect pelagic animals when the water was disturbed. It seems natural to pre- sume, as we have found from our experiments witli tlie Sigsbee cylinder, that this surface fauna only sinks out of reach of the disturbances of the top, and does not extend downward to any great depth. The dependence of all the pelagic forms upon food which is most abundant at the surface, or near it, would naturally keep them Avhere they found it in greatest quantity. "Of course, with the death and decomposition of the pelagic forms, they sink to the bottom fast enough to form an important part of the food supply of the deep-sea animals, as can easily be ascertained by examining the intestines of the deep-water Echinoderms. The variety and abundance of the pelagic fauna, and its importance as food for marine animals, are as yet hardly realized. •' One must have sailed through miles of Salpte with the associated Crustacean, Annelid, and Mollusk larvae, the Acalephs, especially the oceanic Siphonophores, the Pteropods and Heteropods, with the Radio- larians, Globigerina?, and Algas, to form some idea how rich a field still remains to be explored. The variety of the pelagic fauna in the course of the Gulf Stream is probably not surpassed by that of any other part of the ocean." 220 SUPPLEMENT. PRESSURE ERRORS OF MILLER-CASELLA THERMOMETERS. The following report is taken from "JVatiire,'' issue of April 21, 1881, page 595. It treats of a matter contained in the original volume on Deep-Sea Sounding and Dredging, page 109: "Royal Society, April 4^. "Professor Tait communicated the results of his experiments on the pressure errors of the Challenger thermometers, the correction for which, as originally furnished to the expedition, was 0°.5 F. per mile of depth. The mode of experimenting was to subject the thermometers to consider- able pressure in a hydraulic press, which was essentially a strong steel cylinder that was warranted to stand a pressure of 25 tons weight on the square inch. It was supported in an upright position upon a strong tripod stand. Water was filled in from above; and into the upper end of the cylinder there was lowered a tight-fitting plug, which was fixed in position by a transverse steel bolt. The lower end of the cylinder was connected through a narrow copper tube to a hydraulic pump, which, by pumping in water to the cylinder, raised the pressure to the required amount. At three tons pressure an average effect of 1°.5 F. was produced upon the inclosed thermometers. Before drawing any conclusions as to the correction to be applied in deep-sea sounding, it was necessary to consider how far this effect could be explained as resulting from the peculiar con- ditions under which the experiments were made. From the known com- pressibility of glass it was calculated that the volume of the bore of a thermometer tube, closed at both ends, would be diminished by only one- thousandth part for an increase of pressure of one ton weight on the square inch ; and from a direct experiment made with a metre-long tube this was proved to represent very approximately the real effect. Hence it was quite out of the question that this could have any appreciable effect on such comparatively short thermometers as those of the Challenger, which were besides subject to much graver errors, such as those arising from the shifting of the indices during the ascent from the depths, or even from the effect of parallax when taking the reading. The direct action of SUPPLEIMENT. 221 pressure may then be disregarded, and the effect prodaed upon the tlier- mometers in the compression apparatus must be due to secondary effects of pressure, such as evolution of heat. The various sources of heat Averc four: 1. Heating of. the water by compression. This depends greatly on the original temperature of the water, being nil at the point of maximum density (40° F.) and larger for higher temperatures. One-fourth of the total effect is due to this. 2. Heating of the water due to pumping in through the narrow tube. This accounts for three-twentieths of the effect, 3. Heating of the vulcanite frame by compression. This explains another fifth. 4. Heating due to the effect upon the protecting-bulb. This probably explains the remaining two-fifths of the effect. In this last case, however, there is not only compression but distortion; and of the thermal effects of such a strain no one yet knows anything. These four sources of error cannot be supposed to exist under the conditions in which deep-sea temperatures are taken ; and the only other possible source, that, namely, due to the direct effect of pressure, gives rise to an error which requires a correction of only 0°.04 F. per mile of depth. In the course of the description of experiments Professor Tail had occasion to describe the various kinds of pressure gauges which he had found it necessary to devise, the ordinary forms of gauge being altogether useless for scientific work." 85 "% THE PLOTTING OF A LINE OF SOUNDENG S 36 FOR SOUNDING WITH WIRE; LIEUT. COMDR. C.D.SICSBEE.U.S.N.. ASSISTANT, C S 37 W 38 u s COAST SURVEY DEEP-SEA SOUNU]NG AND DREDGING 39 NI) DREDGING ~Jir u S. COAST SURVEY DKEP-SF.A SOUNDING AND DRF^DdlNG 41 US. COAST siTHVKY DEEP-SEA SOUNDING AliP DREDGING •noixviioa 'ivioi^i^o