Mr. President, Gentlemen:
It is within the last thirty years only that any material addition has been made to our information as to what lies beneath the surface of the sea. For centuries men had speculated as to the depth of the ocean, but so far as accurate knowledge is concerned, they were completely ignorant. It was long held for instance, that analogy indicated that the deepest parts of the ocean were not deeper than the height of the highest mountains. Bat early experiments with long lines and heavy weights, seemed to show that the ocean's depths were unfathomable. Indeed, many exceedingly intelligent persons, among whom I may cite the late Vice-Admiral Fitzroy, of the Royal Navy, were of the opinion that a lead could not be made to sink to the bottom of the deepest seas, on account of the increased density of the water under the enormous pressure;—notwithstanding the fact that water had been shown, long before, to be practically incompressible. Irrational conceptions, such as this, of the difficulties attending deep-sea soundings seem to have prevented the accomplishment of much that, otherwise, might have been done. Yet Scoresby, writing in 1817 or 1818, recognizes clearly that the principal difficulty is the uncertain intimation given when the lead strikes the bottom; and he even suggests that this could be remedied if some method could be devised for determining the tension of the sounding line throughout its descent. The earlier devices for sounding all involved the use of a heavy sinker, with a correspondingly large line, and while they answered very well in depths not exceeding a few hundred fathoms, beyond a thousand fathoms they were valueless. If a large line were used the sinker would not carry it rapidly and vertically downward, while a lighter line was incapable of drawing up its own weight along with that of the lead. With a large line no impulse was felt when the lead reached the bottom, and the line would go on running out by its own weight, coiling itself over the lead. Indeed this would happen with any line, and, in most cases, any attempt to check it was attended by its parting. The record of deep sea soundings previous to 1850 is consequently not only meagre, but entirely untrustworthy. It was but a natural sequence to such uncertainty that all sorts of devices should have been resorted to in order to dispense with the use of a line as a measuring instrument. The impregnation of wood by water under the greatly increased pressure was one of these devices, but it was found that the impregnation was practically complete at three hundred fathoms. Ericsson invented a lead in which air was compressed by the pressure of the water, and by the amount of compression the depth was to be estimated, but the instrument failed at great depths. Explosions were resorted to, the velocity of sound in water to be the means of measurement, but alike unsuccessfully.
But great strides have been made in the last thirty years in the development of deep-sea work, and instead of being unable to sound at all, we can now not only sound in deep water, but can do so with ease, certainty and astonishing rapidity. Among those to whom we own this extraordinary advance, officers of our Navy stand in the foremost rank. I am, therefore, about to present a short and, necessarily, an imperfect account of the process of this development, confining myself generally to the achievements of our own countrymen.
In October, 1849, the schooner Taney, Lieut. J.C. Walsh commanding, sailed from New York equipped for deep sea research. Her arrangements for sounding seem to have been made with great care, but she was small and unseaworthy—a vessel of but one hundred tons, that could not keep at sea to complete her cruise. In this little vessel steel wire was first used as a sounding line. I do not know whether the idea of using wire was original with Walsh or not, but it is interesting to note that this, the first attempt at the employment of this material with which the greatest feats of deep sounding have since been done, was by an American Naval officer.
The Taney was supplied with 14,300 fathoms of the "best English steel wire," in five sizes, No's 5, 7, 8, 10, and 13, Birmingham gauge. The wire was tested to one third more strain than it was estimated would be brought upon it. I give Walsh's language in describing how it was marked and prepared for use. "Of this an extent of 7,000 fathoms, weighing eighteen hundred lbs, (the remainder, consisting of the smaller sizes. No's 10 and 13, being stowed away as spare wire,) carefully measured and marked with small copper labels, was linked into one piece, and wound upon an iron cylinder 3 feet in length and 20 inches in diameter—the larger sizes being wound first so as to be uppermost in sounding. Two swivels were placed near the lead, and one at each thousand fathoms, to meet the danger of twisting off by the probable rotary motion in reeling up. The cylinder with the wire was fitted to a strong wooden frame, and machinery attached,—fly-wheel and pinions, to give power in reeling up. Four men at the cranks could reel up with ease, with the whole weight of the wire out. Iron friction bands, which proved of indispensable importance, were connected to regulate the running off the reel. One man, with his hand upon the lever of one of these friction bands, could preserve a uniform, safe velocity, checking or stopping the wire as required. The whole apparatus could be taken apart, and stowed away in pieces (being so large and massive, this was indispensable in so small a vessel as the Taney.) When wanted for use the frame was put together and secured to the deck by iron clamps and bolts, near amidships, the reel hoisted up from below and shipped in its place; a fair leader was secured to the taffrail, being a thick oak plank, rigged out five feet over the stern, having an iron pulley, 18 inches in diameter, fitted in its outer end, and two sheet iron fenders 3 ½ ft. long, of semicircular shape fitted under it to guard the wire from getting a short nip in the drifting of the vessel. The wire was led aft from the reel, over the pulley which traversed freely in the fair leader, and passed between the fenders into the water."
The first trial of this apparatus was made on Nov. 15th, 1849. The sinker used was a ten pound lead, and attached to the wire was an instrument, weighing six pounds, invented by Maury for recording the depth descended by the sinker. The cast was made under the most favorable circumstances; the sea was smooth and there was hardly a breath of wind. The wire went down vertically, "preserving," says Walsh, "the exact plumb-line throughout the sounding." When fifty-seven hundred fathoms had run out, the wire broke at the reel, but from what cause we are not informed. It was probably owing to the imperfection of the method used in joining the different lengths of wire together.
Walsh considered that in this sounding he had proved that the depth of the ocean at the point where it was made (Lat. 31° 59' N. Long. 58° 43' W), about four hundred miles east of Bermuda, was not less than fifty-seven hundred fathoms. This depth was marked upon the chart with the sign of "no bottom." After a few years, however, Maury caused the sounding to be marked "doubtful," and finally in 1857 it was erased from the chart. Walsh's mistake was in using a sinker of too little weight for such large wire. A weight of sixteen pounds became insignificant in comparison with that of the wire (which in water was more than two hundred pounds to the thousand fathoms) when two or three thousand fathoms had run out, and consequently the shock when the sinker touched the bottom was inappreciable. The depth at the point where the sounding was made is between twenty-five hundred and twenty-eight hundred fathoms.
Several other unsuccessful attempts were made by the Taney to sound with the wire, but in every instance the wire broke when about two thousand fathoms had run out. This material was, therefore, deemed unfitted for the purpose and its employment was discontinued. Lt. M.F. Maury, who was very active in the study of the ocean at that time, came to the conclusion that no reliance was to be placed upon soundings made in great depths with wire. But the experiments of Walsh incited the Navy to new exertions. Sounding twine was substituted for wire; instructions for its use were prepared and issued, and a supply of twine furnished to every vessel in commission. This twine was of two sizes—the smaller was capable of supporting a weight of seventy pounds, the larger would bear one hundred and fifty pounds. Ten thousand fathoms of the small twine, and five thousand of the large was supplied to each ship. The sinkers to be used were one or more 32 pdr. shot. The smaller twine was to be employed in great depths where there was little probability of recovering the shot; the larger, when it was probable the sinker might be recovered.
Among the first to use the twine was the sloop-of-war Albany, Commander Piatt, which proceeded to sea in 1850. The officers of the ship entered heartily into the work, but the experiments were conducted under the direct supervision of the first Lieutenant, Wm. Rogers Taylor. The twine was wound upon a "delicately constructed reel which would turn with as little friction as possible." It was at first thought that this light line, weighing but a pound to 160 fathoms, would cease running out when the shot struck the bottom, or that it would, at least, move so much more slowly that the instant could be determined. This supposition was afterwards proved in error and consequently the first soundings, which, indeed, were little better than guesses by the feel of the line, were subsequently discredited. Many discouragements were encountered, but they persevered. The twine proved of bad quality breaking frequently when two or three hundred fathoms had run out, and we find recorded as lost in making one cast, as many as eleven shot. The line was overhauled fathom by fathom; weak portions were weeded out; and so at the end of six months they had made thirty-six casts. During this period the Albany expended forty thousand fathoms of twine, and in no instance where the depth exceeded one hundred fathoms was the shot recovered. In December 1851, the ship was supplied with new twine, which had been very carefully made. One thousand fathoms of this weighed 8 ¾ pounds. It was overhauled as before, the lengths were reknotted and parts of it were waxed. Notwithstanding these precautions, the line continued to part, but still much good work was done, and the experience thus gained was of great value to those who were to follow. As a result of these soundings it was demonstrated that the line would not cease running out when the sinker touched the bottom and that the feel of the line was an uncertain indication as to whether the sinker was on the bottom or not. It was also found impossible to make a cast from the vessel in any except the calmest weather. It was shown that the waxed twine would go down more rapidly than when unwaxed; and it was found that the twine, although tested to 70 pounds, would not weigh a 32 pound shot, owing to weak places, and the frictional resistance of the water.
Near the close of the Albany's work Taylor adopted a suggestion of Maury's and noted the time of running out of each hundred fathoms. The result is remarkable as indicating for the first time a means of determining with some degree of accuracy the instant when the sinker touches the bottom. It was found that from the beginning of the cast the time of running out of each hundred fathoms gradually increased, so that if at any particular hundred fathoms the time interval was increased more than its due proportion it was an indication that bottom had been reached. This was, probably, the most important fact developed by this cruise. So important did it seem to those interested in deep sea soundings at that time that the method was immediately adopted, and in nearly all, if not all subsequent casts it has been used. In the recent Challenger expedition it was the only method adopted for determining when the sinker was at bottom. The neglect in observing this time interval properly or the failure to interpret it correctly led Lieut. J.P. Parker of the Congress to report, in 1852, a sounding of eighty-three hundred fathoms; Capt. Denham of H.M.S. Herald, one of seven thousand, seven hundred six fathoms, the same year; and Berryman, in 1853, one of sixty-six hundred fathoms. Denham did observe the time of running out of each five hundred fathoms, but an examination of his record shows that the bottom was reached at between twenty-three hundred and twenty-eight hundred fathoms. Parker did not observe his time intervals regularly, nor did Berryman. Maury estimates that Parker reached bottom in about twenty-eight hundred fathoms, and Berryman was afterwards satisfied that his sounding was incorrect.
Such was the state of affairs when the first really successful deep sea sounding expedition was organized. This was in 1852, in the Brig Dolphin, under the command of Lieut. S.P. Lee. Profiting by the experience of the Albany, Lee caused his sounding twine to be carefully examined as it was received, and rejected thousands of fathoms. Notwithstanding his supervision, much of the line was still defective, and of the first seventeen casts made, only the last was successful. Lee soon repeated the experience of Walsh and Taylor—only in the smoothest states of the sea, and in calm weather could good easts be made from the vessel. He, therefore, adopted the expedient of sounding from a boat, which by means of an oar on either side could be kept over the line. By doubling his line for the first two or three hundred fathoms he prevented its carrying away, and after that there was little trouble in obtaining quite reliable casts. Lee always noted his time intervals, though he did not always correctly interpret them. With a heavy sinker and a light line the shock when bottom is reached can usually be detected by those experienced in the work if proper care be used. But this method is uncertain and the officers of the Dolphin were frequently led into error by adopting it.
The problem of deep sea soundings was so far solved. The depths of the ocean could be determined at the expense of a 32 pound shot and a little inexpensive twine. The conditions necessary were a heavy, though not excessive, weight; a smooth, light line; some means of keeping the sounding vessel over the line; and an accurate record of the time required for running out of each fifty or one hundred fathoms. The soundings of the Dolphin under Lee, and his successor Berryman, are universally recognized as the first ever made in the deep sea with any degree of accuracy.
But the subject was not allowed to rest at this point. Hitherto when a cast had been made the line had been cut or parted, so that no specimen of the bottom had been brought to the surface from any great depth. In order that a more complete knowledge of the bottom of the sea could be obtained, some contrivance for bringing up a sample of the soil became requisite. Heretofore this had been done only by weighing the sinker, to which some form of cup was attached and, indeed, it had never been accomplished at depths exceeding a thousand fathoms. The sounding twine was not strong enough to weigh the shot, and some other device was necessary. At this stage, about 1854, Passed Mid'n Jno. M. Brooke appears with his apparatus, by which the shot could be detached when it reached the bottom, and the instrument with a specimen of the bottom could be lifted again to the surface. I need not describe this invention, every one present is familiar with it. With some modification of its original form it remains to this day the most successful instrument of the kind ever invented. With it Berryman obtained specimens from depths exceeding two thousand fathoms, and Belknap has repeatedly brought samples of the bottom from more than four thousand fathoms.
Brooke's invention gave a new impetus to the work of sounding. Equipped with this instrument Berryman again (in 1856) put to sea in the Arctic, and sounded all over the North Atlantic. One result of this cruise was the discovery of what has since been called "the telegraphic plateau." Berryman's soundings showed that between Newfoundland and Ireland, there existed a remarkably uniform depth of water not differing much from two thousand fathoms. As soon as this discovery was announced the project of connecting the two countries by a submarine telegraph cable was agitated. Berryman made twenty-four casts on a great circle between St. Johns and Valentia, with a view to determining the practicability of the scheme. He was followed, in 1857, by Capt. Dayman of the Royal Navy who in H.M.S. Cyclops went over the same ground, making thirty-four casts. Dayman used Brooke's detaching apparatus with Massey's sounding machine, by which the depth was recorded. Brooke's original invention had already been modified by Berryman, who replaced the shot by a long leaden cylinder thus to diminish the resistance to the descent, and also adapted a valved-cup to the end of the sounding rod. Capt. Dayman made similar modifications, and in addition replaced the rope slings of Brooke's original device by wire ones which were more readily detached. Massey's sounding recorder was found to be useful as a check upon the soundings, but for some reason, difficult to explain, it is not a reliable instrument in deep water.
From the time of Berryman's soundings in the Arctic, the U. S. Navy took but little part in deep sea work, for several years. The English Navy, however, continued the work with great activity. Brooke's detaching arrangement was universally employed. Its use had gradually introduced the intervention of larger lines, but in 1860 we find H.M.S. Bulldog adopting the old plan of a cod line and an iron sinker, the line being cut at each cast. In this cruise, however, the soundings were usually repeated with a detaching sinker and larger line in order to obtain bottom specimens. Many efforts were made to invent a machine which would bring up larger bottom specimens, but the methods of sounding hardly varied. The use of steam rendered the lowering of boats unnecessary, as a steamer could be kept over the line when sounding. Small engines were also introduced for reeling in the line, thus diminishing greatly the labor of obtaining a cast.
The progress which had been made in deep sea sounding, in 1870, can best be indicated by a description of the process as practiced on board the Porcupine in that year. This vessel, commanded by Staff-Commander Calver of the Royal Navy, was operating under the auspices of a committee of the Royal Society, with Prof Wyville Thomson as scientific director. The following extract from Prof. Thomson's book, entitled "The Depths of the Sea," describing a cast made in two thousand four hundred and thirty-five fathoms presents the art of sounding in its most perfect development at that period.
"The 'Porcupine' was provided with an admirable double cylinder donkey-engine of twelve horse-power (nominal) placed on the deck amidships with a couple of surging drums. This little engine was the comfort of our lives; nothing could exceed the steadiness of its working and the ease with which its speed could be regulated. During the whole expedition it brought in, with the ordinary drum, the line, whether sounding line or dredge rope, with almost any weight, at a uniform rate of a foot per second. Sometimes we put on a small drum for very hard work, gaining thereby additional power at some expense of speed.
Two powerful derricks were rigged for sounding and dredging operations, one over the stern and one over the port bow. The bow derrick was the stronger and we usually found it the more convenient to dredge from. Sounding was most frequently carried on from the stern. Both derricks were provided with accumulators, accessory pieces of apparatus which we found of great value. The block through which the sounding-line or dredging-rope passed was not attached directly to the derrick, but to a rope which passed through an eye at the end of the spar, and was fixed to a 'bitt' on the deck. On a bight of this rope, between the block and the bitt, an accumulator was hashed. This consists of thirty or forty or more of Hodge's vulcanized india-rubber springs fastened together at the two extremities, and kept free from one another by being passed through holes in two round wooden ends like the heads of churn staves. The loop of the rope is made long enough to permit the accumulator to stretch to double or treble its length, but it is arrested far within its breaking point. The accumulator is valuable in the first place as indicating roughly the amount of strain upon the line ; and in order that it may do so with some degree of accuracy it is so arranged as to play along the derrick, which is graduated from trial to the number of cwts. of strain indicated by the greater or less extension of the accumulator; but its more important function is to take off the suddenness of the strain on the line when the vessel is pitching. The friction of one or two miles of cord in the water is so great as to prevent its yielding freely to a sudden jerk such as that given to the attached end when the vessel rises to a sea, and the line is apt to snap. A letting-go frame, a board with a slit through which the free end of the sounding machine passed, and which supported the weights while the instrument was being prepared, was fitted under the stern derrick. The sounding instrument was the 'Hydra' weighted with three hundred and thirty-six lbs. The sounding line was wound amidships just abaft the donkey engine on a large, strong reel, its revolutions commanded by a brake. The reel held about four thousand fathoms of medium No. 2 line of the best Italian hemp, the No. of threads, 18, the weight per hundred fathoms, 12 lbs, 8 oz., the circumference 0.8 inch, and the breaking strain, dry, one thousand four hundred and two lbs, soaked a day, one thousand two hundred and eleven lbs., marked for fifty, one hundred and one thousand fathoms.
The weather was remarkably clear and fine; the wind from northwest, force = 4; the sea moderate, with a slight swell from the northwest. We were in Lat. 47° 38' K, long., 12° 08' W., at the mouth of the Bay of Biscay. The sounding instrument, with two Miller-Casella thermometers and a water bottle attached a fathom or two above it, was cast off the letting-go frame at 2 h., 44 m., 20 s., p.m. The line was run off by hand from the reel and given to the weight as fast as it would take it, so that there might not be the slightest check or strain."
(Here follows a table showing the time of running out of each one hundred fathoms, the time intervals varying from 45 seconds for the first hundred to 1 m. 52 sec. for the last.)
"In this case," continues Prof. Thomson, "the timing was only valuable as corroborating other evidence of the accuracy of the sounding, for even at this great depth, nearly three miles, the shock of the arrest of the weight at the bottom was distinctly perceptible to the commander, who- passed the line through his hand during the descent. This was probably the deepest sounding which had been taken up to that time which was perfectly reliable. It was taken under unusually favorable conditions of weather, with the most perfect appliances, and with consummate skill. The whole time occupied in the descent was 33 minutes, 35 seconds; and in heaving up 2 hours, 2 minutes. The cylinder of the sounding apparatus came up filled with fine, grey Atlantic ooze."
This was the sum of our experience in deep sea sounding when, in 1873, the Tuscarora, Comdr. Geo. E. Belknap, was ordered to prepare for soundings in the Pacific Ocean, a field hitherto unexplored. The object of the Tuscarora's cruise was, primarily, to determine a practicable route for a submarine cable to connect the United States and Japan. The original plan comprehended a line of soundings on a great circle, as nearly as might be, from Cape Flattery, Washington Territory, to No-Sima, at the entrance of Yeddo Bay, Japan. Returning, a line was to be run from Cape No-Sima, by the Bonin Islands, to Honolulu, and thence to San Diego or San Francisco. But a short coal supply prevented the completion of the first line, and bad weather, due to the lateness of the season, rendered it advisable to return. On the passage back to San Francisco lines of soundings were run on and off shore to determine the conformation of the bottom near the coast line. This was continued afterwards as far south as San Diego. The southern line was then run, the ship returning by the great circle route to the northward. The results of this cruise, together with a description, of the apparatus employed have been published by the Hydrographic Office, in a fully illustrated volume, to which you are referred for more complete information.
The Tuscarora was supplied with about fifty thousand fathoms of sounding lines. Of this, some forty thousand fathoms was 1 ¼, 1 ½, and 1 ¾ inches Manila rope, which had been treated with carbolic acid, after some patented process, with a view to its preservation. About five thousand fathoms was 1 ¾ inch whale line, and there was also four thousand or five thousand fathoms of Albacore line made of untarred hemp, ¾ inch in circumference. Fitted on the forecastle was a steam reel and a dynamometer, for use with this rope. The want of some instrument for regulating and measuring the tension of the line in sounding had long been felt. As the line runs out the tension is continually increased by the weight of the increasing length overboard, until it is suddenly diminished by the sinker resting on the bottom. If then the tension could be measured at every instant, any sudden diminution of the strain would be an indication that bottom was reached. The dynamometer, designed by Passed-Assistant Engineer T.W. Rae, was for that purpose. It consisted essentially of two fixed pulleys, elevated several feet above the deck, midway between which was a third pulley attached to a rod which was capable of motion in a vertical direction, through guides which it traversed freely. The lower end of this rod, which passed through the deck, terminated in a piston, which worked in a cylinder filled with water. The sounding line passed from the drum of the steam reel over one of the fixed pulleys, under the movable pulley, which was thus made to ride upon the line, over the second fixed pulley, and thence, by means of a fair leader, over the ship's side. The rod attached to the movable pulley could be weighted and by means of a scale behind the rod the strain upon the line could be determined. By gradually increasing the weights on the rod as the line ran out, it was intended to keep such a strain on the line, that it would cease running, or nearly so, when the sinker rested on the bottom. The object of the piston in the cylinder filled with water was to prevent violent motion of the rod, when the ship was rising or falling with the sea. This machine, although constructed upon perfect mechanical principles, and notwithstanding the fact that similar instruments are used with accuracy in the laying of submarine cables, gave hardly satisfactory results. It was found that the oscillations of the rod were violent and incontrollable when there was any rolling motion, and it was impossible to estimate with any degree of accuracy the tension of the line. It is possible that a more thorough acquaintance with this apparatus would make it valuable in sounding with rope. By au unfortunate accident it was not properly arranged in the Tuscarora, and hence did not obtain a very thorough test of its value, before the soundings with wire become so successful that its employment was unnecessary.
We have seen with what success the attempt to sound with wire had been attended in the Taney. Walsh's failure, together with that of other efforts made at about, the same time, led to the conclusion that wire soundings were impracticable. Nevertheless that material offered great advantages and possessed the very qualities which experience had shown to be desirable in a sounding line. The small, smooth wire meeting with but little resistance from the water in descending, would sink rapidly, nor would it be deflected to any great extent by submarine currents; it would require a sinker of comparatively little weight; it could be made sufficiently strong to bear any ordinary strain; it was compact and portable, and would occupy but little room on board ship, a consideration which only those who have been embarked with great quantities of sounding rope, can properly appreciate. There were those, therefore, who did not accept the verdict rendered upon the evidence of former trials. All that was required to render the method practicable, it was maintained, was some contrivance for so regulating the strain upon the wire, that when the sinker reached the bottom, the wire should no longer run out, or should do so with such a diminished velocity as to be readily perceptible. This was the object of a machine invented by Sir Wm. Thomson, in 1872, for sounding with steel piano wire.
One of these machines, with a supply of wire, was furnished to the Tuscarora. At that time but a single cast had been made with the apparatus, and that by the inventor, who sounded in twenty-seven hundred fathoms from a schooner yacht in the bay of Biscay. The east had not been satisfactory; the reel was crushed in the operation, and it was with great difficulty that the wire was hauled in. The original machine differed but little from that furnished to the Tuscarora, so that the method was almost absolutely untried when it was placed in Capt. Belknap's hands for experiment. The weight of opinion both in this country and in England was against the method. When the Challenger was fitting out in 1872, it was reported that she would be furnished with the machine. But she went to sea without it, the reason being, according to Sir. Wm. Thomson, that "innovation is very distasteful to sailors." Prof. Wyville Thomson, who was the director of the scientific staff of the Challenger expedition, in a paper read before the Asiatic Society of Japan, at Yokohama, said, "When we started from England this wire had only been tried once. I had been some years at sea and my colleagues were all sailors, so we had great sympathy with hemp." According to Sir William, the British Admiralty would not try the wire method because it was new. He states that he received a semi-official letter to the effect. "When you have perfected your apparatus we may be willing to give it a trial."
Whether or not it was sailor's prejudice that opposed the use of wire in this country, it is certain that few had any faith in its success. Fortunately, however, among the few, was the Chief of the Bureau of Navigation, Commodore Ammen. It was his determination in the matter that enabled the Tuscarora to put the method to the test. He facilitated the preparation of the ship in every way; he ordered Capt. Belknap to make an experimental cruise to detect defects in his apparatus, which was the foundation of future success; and it is to his aid and counsel and constant interest throughout the work, supplemented by the ingenuity of Capt. Belknap, that the Navy owes its prestige in having made wire soundings practicable.
Thomson's machine as furnished to the Tuscarora, consisted of a reel a (Plate I.) for holding the wire, and an arrangement for regulating and measuring its tension. The reel was a hollow cylinder of galvanized sheet iron, with an iron axle passing through its center, and soldered to its sides. The drum of the reel was about six feet in circumference and three inches long. The ends extended two inches beyond the circumference of the drum, thus forming an annular space two inches deep and three inches wide in which the wire was wound. To one side of the drum was fixed a projecting ring of galvanized sheet iron, which formed with the side of the reel a V shaped groove in which an endless rope passed. The axle of the reel was a small iron shaft, six or eight inches long, which revolved in bearings on two iron standards, bolted to a plank of hard wood 3t ft. long, 15 inches wide and 2 ½ inches thick. The shaft carried on one side of the drum an endless screw, which gave motion to a train of wheel work by which the revolutions of the reel were counted; on the other side was attached a ratchet in which worked a pawl by which the revolutions of the reel was prevented when necessary. Both ends of the shaft projected beyond its bearings and were squared, so that cranks might be applied in putting the wire on the reel.
The arrangement for controlling the tension of the wire consisted of a grooved friction wheel of iron c, ten inches in diameter, the groove being wide enough to carry two parts of the endless rope b h passing around the reel. It was capable of motion in a vertical plane, in an iron crotch fixed to the bed of the machine, but was prevented from turning by a cord e, passing from the lower part of its circumference to the dynamometer. The friction wheel was connected with the reel, when the wire was running out, by means of an endless rope b, of 9 thread untarred hemp, which passed around the V groove of the reel, then up, over, and once around the friction wheel, and then around a pulley d placed several feet in rear of the reel. This pulley was attached to a small tackle by means of which the endless rope could be made more or less taut, thus increasing or diminishing the resistance of the friction wheel. The tackle was shortly afterwards replaced by a pendant f rove through a tail block, and carrying hooks to which weights could be attached, an arrangement of much greater utility.
The dynamometer was an instrument similar to one form of the spring balance, secured to the bed of the machine. The force exerted upon it, which depended upon the tension of the wire, was indicated in pounds, by a pointer which moved over a graduated scale. For this dynamometer was afterward substituted an ordinary spiral spring balance, g which gave more satisfactory results.
The wire furnished for this machine was steel piano wire, No. 22, B.W.G., of the best English make. Its weight in air was about 14 lbs., and in water 12 lbs, to the thousand fathoms. It would support a weight of 230 lbs. It was supplied in lengths of from two hundred to four hundred fathoms which were spliced together on board ship. One great objection which had been urged against the use of wire was the impossibility of making the splices strong enough. The method of splicing adopted on board the Tuscarora was to lap the ends about two feet, solder one end and lay the other end up in turns of about an inch in length until it was all expended, when the second end was soldered. The two parts of the splice were also soldered together at intermediate points, and the whole splice served with well waxed twine. The splice thus formed was very strong, not one of them having broken down during the cruise. The wire was received packed in sperm oil in cases of sheet tin; it was kept in these cases covered with oil until wound upon the reel for use. The operation of winding was one requiring the utmost care, the wire having a great tendency to kink. When, by accident, a kink did occur it was found best, as a rule, to break the wire and splice the ends. In winding, the coil of wire was taken from the oil and slipped over the end of a wooden reel, from which it was wound on the sounding reel, being kept hand taut all the time. It was carefully measured as it was wound, the lengths between the splices, as well as the number of revolutions of the drum, being noted at each splice. These were recorded in a notebook and by them the depth was determined when a cast was made. The reel held readily between four thousand and five thousand fathoms and this quantity was usually wound upon it. When it was all on, to the free end of the wire was attached a small grommet made of 1 ½ or 2 inch rope. The grommet was secured by sticking the end of the wire between the strands of the rope and then taking several round turns against the lay, the whole being finally served. A piece of cod line attached to the grommet and tied around the reel prevented the the wire from unwinding.
The required length of wire being wound, the reel was unshipped and placed in a galvanized iron tank containing a solution of caustic soda, which served to protect the wire from rust. The philosophy of this method of preservation, as explained by Sir. Wm. Thomson is as follows: "The preserving effect of alkali upon steel is well known to chemists. It seems to be due to the alkali neutralizing the carbonic acid in the water, for the presence of carbonic acid in water is the great cause of iron being corroded. The fact is well established that iron will remain perfectly bright in sea-water rendered alkaline by a little quicklime. Caustic soda is a more sure material, because with it we can make more certain that the water is really alkaline. * * * All that is necessary in order to made sure that the pickle will be a thorough preserver of the wire is that it should be found to be alkaline when tested with the ordinary litmus test paper.
I give Sir Wm.'s language as nearly as may be because I do not think he estimates at its true value the action by which the wire is preserved from rust. In the Tuscarora the lye in which we kept the wire was much more strongly alkaline than he says is necessary. It was found, however, that while the wire was perfectly preserved, the caustic soda solution attacked the zinc of the galvanized iron of which the reel was made, as well as the soldered splices. Now zinc and iron, or iron and tin solder, when placed in contact in caustic soda form a galvanic couple of which the zinc or the tin solder is the electro-positive element. A galvanic action is, therefore, set up by which the iron is preserved at the expense of the zinc or tin. It is probable that this action would be less with a more dilute solution of soda than with a stronger one, but still great enough to protect the sounding wire from rust. This, I think, is the true explanation of the preservative action. If so, it seems to me that a more suitable liquid than soda-lye might be substituted for it. Caustic-soda is a very disagreeable substance to use on board ship. It spoils the clothes and hurts the hands of those working with the wire; and the lye, washing over the sides of the tank in the 'rolling of the ship, kills the wood of the deck, and then running through the scuppers takes the paint off the ship's side. I am inclined to think that slightly acidulated fresh water, or even sea-water alone might be substituted for it with advantage. So serious has the objection to the use of soda become that it has been discarded in English vessels using the wire, and sperm oil is now used in its stead.
The Tuscarora's soundings were always made under steam and with the ship stern to wind. This was found to be the best method of laying the ship and it was resorted to even when the force of the wind was as great as 8. Usually the screw held the stern of the ship up to the wind, but when the bows showed a tendency to fall off to one side or the other, which was the case only when the wind was light, the jib being set with the sheet hauled flat aft effectually prevented it. After numerous experiments Capt. Belknap fixed upon the gangway as the most convenient point from which to sound. There the motion of the ship was least sensible, the wire was consequently more manageable, and accordingly nearly all the soundings were made there. A bridge across the deck was constructed, so arranged that it could be unshipped and stowed away in port. The machine was placed upon a slide so that it could be run out or in and compressors were applied to secure it at any point. The upper grating of the accommodation ladder being shipped, this slide was supported by a railing and securely lashed. The grating allowed room to the men who were handling the sinker &c., and served to carry the wire well out from the ship's side.
In preparing to sound, the reel was placed on its bearings at the gangway, and the bed run out to the end of the slide. The endless rope was arranged as already described. To the grommet was hitched a piece of Albacore line, twenty-five fathoms in length, and this was also wound on the reel. The other end of the Albacore line carried a small iron rod six feet long, to which was seized the upper end of the swivel-link of the Brooke detaching apparatus. The Albacore line was to prevent the wire itself from going to the bottom, thus avoiding all danger of kinking, and the rod was for the purpose of throwing the line clear of the specimen cylinder so as to prevent fouling. The sinker, which was usually an 8 in. shot weighing 55 lbs, was placed on the apparatus for obtaining the bottom specimen, an invention of Capt. Belknap, shortly to be described. When all was ready the sinker was eased down by hand into the water, and a Miller-Cassella deep-sea thermometer, for obtaining the bottom temperature, was attached to the stray line above the iron rod. The stray line was then allowed to run out slowly until the grommet in the end of the wire was reached. To this was attached a lead weighing four pounds, which prevented the end of the wire from flying up and kinking when the sinker reached the bottom, as experience had shown it would sometimes do. Weights were now hooked to the pendant carrying the pulley around which the endless rope passed, and the wire was allowed to run out. When it had fairly started, the weight on the pendant was diminished so as to allow it to run more rapidly. The time the wire started was noted, as well as the instant at which the drum completed each hundred revolutions. When it was thought that the sinker was nearing the bottom, the weights on the pendant were increased in order to diminish the speed of the reel and to make sure that the instant of reaching the bottom should be properly indicated. This indication was usually unmistakable; the pointer of the dynamometer would fly back on the scale, and, except in very deep water, the revolution of the drum would almost instantly cease. The fact that bottom had been reached could be noted as well from the poop or the forecastle as at the gangway.
Bottom having been found, the cord holding the friction wheel was detached from the dynamometer so that the endless rope might be employed in reeling up the wire. The officer in charge of the sounding then laid hold of the endless rope and, unaided, hauled in a few fathoms to make sure that the shot had been slipped. If not, as was the case in but few instances in the early part of the cruise, fifty or sixty fathoms were reeled in and again let go, the second effort almost invariably detaching the shot. The reeling in was at first done by putting men on the bridge who hauled in hand over hand on the endless rope, an operation both tedious and laborious. For this arrangement was afterwards substituted a fly-wheel, carrying a grooved disk of wood from which a belt passed to the V groove of the reel. By turning the fly-wheel by means of long cranks, which could be manned by four or six men the wire was wound in much more rapidly and uniformly than by the old system. When reeling in the wire was guided fair on the reel by two petty officers, round sticks being used for the purpose.
In Brooke's original apparatus the device for obtaining specimens of the bottom consisted of a number of open quills placed in the lower end of the sounding rod. This arrangement, however, did not secure adequate samples, and the ingenuity of those engaged in deep sea work has ever since been directed toward its improvement. Berryman soon replaced the quills with a valved cup, which gave much better results. Many subsequent improvements in the form of the cup have been made, not a few of which have been by officers of the Navy, In the Challenger, the apparatus usually employed was the "Hydra," so called because it was invented on board an English surveying vessel of that name. The Hydra consists of a long cylinder of brass, closed at its lower end by a valve, opening upwards. An iron piston-like rod, carrying a short arm projecting at right angles to the rod, is fitted into the upper end of the cylinder. Over the projecting arm is a curved steel spring, one end of which is fast to the rod, the other end movable. This may be pressed flat against the rod, a hole in the spring allowing the projecting arm to pass through it. The sinker is supported on the rod by a wire sling which passes over the arm and is kept there in opposition to the spring, by the weight of the sinker. When the sinker rests on the bottom the sling is pushed off the projecting arm by the spring, and the rod and cylinder are hauled up. The piston-like arrangement of the rod assists in closing the valve in the lower end of the cylinder.
This apparatus had been used very successfully in the Porcupine, and was highly thought of in the Challenger. Its weight, however, made it objectionable for use with wire, and it necessitated the use of a separate instrument, the water-bottle, when samples of the bottom water were required. In order to overcome these objections several new forms were devised by Capt. Belknap. Of these the most important and most successful are those designated as specimen cylinders, No's 1, 2, and 3 (Plate II.) In each of these the Brooke plan of detaching is adhered to.
Cylinder No. 1 (Fig. 1) consists of two cylinders a and b, the inside diameter of the one, h, being very slightly greater than the outside diameter of the other, a, so that the larger slides over the smaller with but little friction. The inside cylinder terminates in a cone, d, above which, on two opposite sides, are openings, by which the bottom mud or sand can enter. The upper end of this cylinder screws on the iron detaching rod c. The outside cylinder travels on this rod by means of an opening in its top. It is long enough to go entirely through the shot used as a sinker and, when in its lowest position, it covers the openings in the inner cylinder. A stud on one side prevents its slipping through the shot. The inner cylinder has in its upper part a chamber, vi, to the top and bottom of which are fitted valves, n n, opening upward, intended to enclose a specimen of the bottom water. In slinging the sinker this apparatus is passed through a hole in the shot, and a metal washer, I, is put on, which by means of wire slings is suspended to the detaching arm, f, of the rod. When the shot rests on the bottom, the detaching arm falls, the outer cylinder slips down and retains whatever has entered the inside cylinder.
Cylinder No. 2, (Fig. 2,) is of quite different design. To the lower end and inside of the cylinder is fitted a hollow frustum of a cone, h, its base downward. The upper end of the cone is closed by a valve, h, kept in place by its own weight in addition to a light spiral spring. Into the bottom of the valve is screwed a plunger, p, extending beyond the end of the cylinder. When the shot strikes the bottom, the valve is forced open and the mud or sand enters. The valve then closes, retaining the specimen. This cylinder is also fitted with a water space.
Cylinder No. 3, (Fig. 3,) consists of an auger shaped piece of iron, a, over which slides a brass cylinder. The brass cylinder is kept up by a stud, l, on its side, until the shot is detached. The auger shaped iron engages the bottom specimen which is retained by the cylinder. In the use of this cylinder it was sometimes found that the metal washer which supported the shot was caught by the cylinder in falling, and prevented the shot from slipping off. This was remedied by lacing on the shot two wire grommets of smaller diameter than the shot, to which the slings were attached.
Cylinder No. 1 was most successful in soft bottom, at moderate depths. No. 2 brought up the best specimen in hard, sandy bottom, and was always good. No. 3 answered best at great depths, when the shot on striking the bottom was not moving with great velocity.
In depths less than two hundred fathoms the sinker used was an 8 inch shot, weighing about 55 lbs. In deeper water one or more lead castings, which fitted over the top of the shot, were added, thus increasing the weight to 70 or 75 lbs, and making the total weight sent down, including the specimen cylinder and the small safety lead, about 80 lbs.
The time required for a sounding with this apparatus is much less than that required for rope, even when the rope is reeled in by steam. The deepest sounding made by the Porcupine in 1869 and '70 was the one of twenty-four hundred and thirty-five fathoms, a description of which I have read. The sinker used on that occasion weighed 336 lbs. The time required for the descent of the line was 33-2 minutes, and in hauling in, 2 hrs. 2 min. or 2 hrs. 35 minutes for the cast. In the Tuscarora we sounded in twenty-five hundred and sixty-five fathoms, the line running out in 31 minutes, and being reeled in in 40 minutes, the whole time occupied being but 1 hr. 11 min., a gain of 1 hr. and 2-4 minutes, although the depth was over a hundred fathoms greater. This is a very fair example of the speed with which a wire sounding could be made. A cast of three thousand fathoms usually required an hour and a half, and one in four thousand could be made in about two hours.
The Tuscarora ran lines of soundings aggregating sixteen thousand six hundred and twenty miles in length, and made in all four hundred and eighty-three casts, of which perhaps fifty, in depths generally less than five hundred fathoms, were made with rope. The depth found in one hundred and sixty of the casts was over two thousand fathoms; thirty-two were in depths of more than three thousand, and nine, in depths of more than four thousand fathoms. The greatest depth from which a bottom specimen was obtained was four thousand three hundred and fifty-six fathoms. The deepest sounding made was in four thousand six hundred fifty-five fathoms, or 5 ¾ statute miles. The circumstances under which this cast was made were all the most favorable. The sea was smooth, the ship steady, and the up and down direction of the line was maintained throughout. The indication of the dynamometer that bottom had been reached was perfect. But the wire had been down four thousand fathoms three or four times on the preceding day, and it finally gave way under the strain when about four hundred fathoms had been reeled in. This was the fifth and last time during the cruise that the wire was lost.
The soundings with the wire were invariably made by the navigator of the ship, Lieut. Geo. A. Norris, and it was to his industry and intelligence that their success was in a large measure due. To Capt. Belknap, however, we owe the perfection which this method has attained. He was indefatigable in the work and every cast was made under his direct supervision. Both Commodore Ammen and Sir Wm. Thomson were, naturally, much gratified at the results of the cruise. The latter has repeatedly publicly referred to the fact that while the British Admiralty hesitated, the American Navy perfected his apparatus in its own way. In his presidential address before the Section of Physics of the British Association, he speaks enthusiastically "of Commander Belknap and his great exploration of the Pacific depths by piano-forte wire, with imperfect apparatus supplied from Glasgow, out of which he forced a success in his own way, and of the admirable official spirit which makes such men and such doings possible in the United States naval service."
The great difficulty that was experienced in the Tuscarora and which the resources of the ship could not overcome was the crushing of the reel, especially when the soundings were in deep water. The steel wire stretching under the strain to which it was subjected, was reeled tightly on the drum. The crushing force thus brought upon the drum by the elasticity of the wire was very great, and the drum, being made as light as possible in order to keep its inertia small, invariably broke down. A drum would stand, perhaps, a dozen casts in depths below two thousand fathoms, but when the depth was much greater the life of a drum was much less. The reels on board the Tuscarora were constantly in the hands of the tinsmith. They were strengthened by radial pieces of wood, placed inside of them, but the crushing went on almost as fast as though the wood were not there. Other devices were resorted to but unavailingly, and the only way of keeping at work was to shift the wire from reel to reel as they broke down. Capt. Belknap recommended a steel drum for deep soundings but I do not know that any have been constructed. Sir Wm. Thomson has overcome this difficulty by the introduction of an auxiliary wheel in reeling in, the use of which is illustrated by the accompanying figure, Plate III.
The bed of the machine, B, rests on two rails, H H, so that it can be run out or in, and clutches, c c, at either end of the bed keep it on the rails. The galvanized sheet iron reel is retained, and the soundings are made directly from it as before. Under the rails, H, and midway between them are two pulleys, I and K, one of which, I, projects over the taffrail, supposing the sounding to be made from the stern as Prof. Thomson prefers. This outermost pulley is called the "castor pulley" from the manner in which it is mounted. Its bearings are in an oblique fork which turns about a horizontal axis, like the castor of a piece of furniture laid on its side. The other pulley, K, is inboard. The two bearings of its axle are both on the same side of the pulley so that a turn or two of the wire can be taken around it. The ends of its axle are squared so that handles may be applied in reeling in, or a wheel having a sharp V groove can be shipped, carrying an endless rope by which the reeling in is done. When the sounding has been made the wire is stoppered and the reel run in about five feet on the slide, until it is just over the auxiliary pulley K. The wire is then led over the castor pulley and a turn, or two turns, are taken around the auxiliary pulley. The reeling in is performed by the auxiliary pulley which takes from two-thirds to nine-tenths of the strain off the wire before it reaches the sounding reel. A, on which it is wound as the reeling in proceeds. The castor pulley, by turning about its horizontal axis, in case the ship drifts during the operation, prevents the wire from leaving the groove; it performs the same office if the ship is rolling heavily. Additional security is obtained by a guard, f, to catch the wire if it should get off the pulley.
In the machine, as thus modified, the inventor has introduced a friction arrangement different from that used in the Tuscarora, and has abandoned the spring dynamometer. A rope fastened to the bed of the machine at a passes over the V groove of the reel and then over two small pulleys F. To the end of this rope weights, g, are applied. These are added as the wire runs out so that the friction brings the drum to rest as soon as the sinker touches the bottom. The rule is to apply a resistance greater by ten pounds than the weight of the wire out. This makes the moving force on the sinker ten pounds less than its weight in water and a sinker of thirty-five pounds is thought to be sufficient in depths less than three thousand fathoms.
The machine, as thus modified, was used in the cable ship Hooper in laying the submarine cables on the coast of Brazil; it was also used in the Faraday, in laying the direct Atlantic Cable. In these ships the sinker was always recovered, and Sir Wm. Thomson recommends that this should be done whenever the depth is not over three thousand five hundred or three thousand fathoms.
One difficulty remained to be overcome. When the ship is lifting in a heavy sea there are times when a very great strain is imposed upon the wire and when it would be dangerous to haul it in too fast. Prof Jenkin, of the University of Edinborough, who accompanied Sir Wm. Thomson in the cable laying expeditions, has invented an arrangement by which the hauling in may go on as rapidly as possible, without bringing more than a certain safe strain upon the wire. The wire will come in fast when the strain is easy, and not come in at all when it is too great. By this arrangement steam can be applied to reeling in the wire. I regret that I do not know the details of this exceedingly important device.
A most valuable and ingenious improvement in the Thomson sounding machine has been made by Lieut.-Commander Sigsbee, U. S. Navy, who has been engaged in sounding in the Coast Survey steamer Blake. In the Tuscarora, whenever the ship was rolling during a sounding, the revolution of the reel would almost cease when the ship rolled toward the wire; on the other hand when the roll was in the opposite direction the reel would move so rapidly that it would have thrown the wire off, if the motion had not been controlled. This was done by pressing with the hand on the endless rope, but this brought an undue strain upon the wire. Sigsbee's invention controls the motion of the machine automatically. I have never seen the machine as improved by Sigsbee, nor have I been able to obtain a drawing of it. The following description and accompanying figure, (Plate IV. Fig. 1.), are in accordance with what I have been told about the device.
On either side of the bed of the machine, at its outer end, is an upright stanchion, A. Between the two stanchions is a horizontal bar, (shown in section at B), which moves up and down in slots or scores in the uprights, A. A fixed cross-piece joins the upper ends of the two uprights, and the movable bar is connected with the cross-piece by two spiral springs, D. Attached to the under side of the movable bar is a pulley, C. To the strap of this pulley is secured one end of the brake rope m n. This is led around a small pulley, p, on the bed of the machine, then carried around the V groove of the sounding reel, and its end made fast to a small eye bolt, u. When there is no downward strain on the bar, B, the springs cause the rope to press tightly against the reel, and keep it from revolving. The wire, instead of passing directly from the reel into the water, is led over the pulley, C. Consequently when considerable strain is on the wire the springs are stretched, the brake rope is slacked and the reel may turn freely. Any tendency of the reel to pay out the wire more rapidly than the sinker will take it, is attended by a diminution of the strain on the wire; the springs contract and the brake-rope is applied to the reel. The changes in the tension of the wire being thus self regulating it is evident that no dangerous strain can be brought suddenly upon it.
Although not strictly within the scope of my paper, I have thought it well, at this point, to speak of the most recent application of the piano wire in sounding. I refer to its substitution for rope in sounding in shoaler water for the ordinary purposes of navigation. The uncertain process hitherto adopted, involving the necessity of stopping or heaving to the ship, and depending upon the shrewdness in guessing of the quarter master, is no longer necessary. In laying the telegraph cables on the coast of Brazil, Sir Wm. Thomson used the ordinary deep-sea machine in making approximate soundings in depths of from fifty to one hundred and fifty fathoms while the ship was running at the rate of four or five knots. The depths in these cases were arrived at by noting the length of wire out, and knowing the distance run by the ship while it was going out, and were therefore only rough approximations. He has, however, recently modified his apparatus so as to make it available for "flying soundings," and they have been made with great accuracy. The reel used for this purpose is of the same form as that for deep soundings, but it is only twelve inches in diameter and holds only three hundred or four hundred fathoms of wire. The brake arrangement differs somewhat in form from that of the larger machine. The weight, E, (Plate IV, Fig. 2), is centered at N, and at D is fastened to the brake- rope, M. The rope, M, takes a single turn around the periphery of the drum, B, and passes over the pulley, G, to which it is attached at F. H is an adjustable weight carried by the pulley, G, and, from its horizontal position, o, it can be raised to the positions indicated by n and m. When it is in the position shown, E is at its highest position against the stop, K, the maximum stress is on the rope, and the maximum friction is on the drum, because both weights, E and H, pull on the ends of the rope with their maximum effect. This is sufficient to prevent the reel from turning. When H is at the position n, the weight, E, hangs between the stop and the base of the machine. A, and the pull on the rope is about seven pounds, which corresponds to a frictional resistance on the drum of about five pounds. When H is in its highest position, m, E rests on the stand and the friction of the drum is almost entirely removed. When the sounding is made, H is raised to the position n; as soon as bottom is reached, which is shown by a sudden decrease in the speed of the drum, the weight, H, is allowed to fall to the position, o, and prevents any more wire running out. A counter is used to show the number of revolutions of the drum. The wire is reeled in by applying cranks, worked by two men, to the axle of the drum.
The sinker is a slender cylinder of iron, three feet long, weighing twenty-two pounds, attached to the wire by a fathom and a half of log line. The depth is determined by the compression of a column of air contained in a glass tube, closed at one end, two feet long and about 1 in. internal diameter. The tube is coated on the inside with a colored substance which is discolored by contact with sea-water. The glass tube, to secure it from breaking, is inserted with its open end downward in a slightly larger tube of brass, made fast to the log-line above the sinker. As the sinker descends, the pressure of the water reduces the volume of the air in accordance with Boyle's law, the water rises in the tube, and the height to which it rises is marked by the discoloration of the chemical preparation within the tube. A graduated scale is applied to the tube by which the depth in fathoms is determined by the extent of the discoloration.
There is no reason why such an apparatus should not be carried on board every ship. The frame of the machine could be secured to the taffrail when the ship is on soundings. "Two men," says Sir Wm. Thomson, "can take a cast with ease every quarter of an hour." It is not necessary to stop the vessel or heave her to in making a cast. The depth indicated by the tube depends only on the vertical distance descended and is independent of the inclination of the wire. Nor is it necessary to use the chemically prepared tube each time. If the speed of the ship be uniform, the reading of the counter when the tube is used will show the relation between the depth and the length of wire out, and the succeeding three or four casts could be estimated entirely by the counter. This apparatus has been used successfully in H.M.S. Minotaur when the ship was going ten knots, and it is reported that a sounding has been made with it from one of the White Star Steamers when the speed was sixteen knots.
The Tuscarora having demonstrated the feasibility of the wire method, the art of deep-sea sounding has been revolutionized. The days of rope soundings terminated last year with the cruise of the Challenger. With the exception of those made in that ship every deep sounding within the last three years has been made with wire. The inconsiderable labor necessary in making a cast, the short time required for the purpose, the accuracy of the result, are such that, henceforth, the bed of the ocean lies but at our hand. "International cooperation alone is necessary in order that the principal features of the bottom of the sea may be mapped out with almost the same accuracy as that with which the geographer now depicts the land surface." In every step toward this wonderful result—wonderful, when we consider the few years in which it has been accomplished—those to whom we are united by ties of official brotherhood have largely contributed. It is to preserve the recollection of this fact that I present this imperfect record of their achievements.