During the year 1891, the U.S.S. Baltimore was not docked for eleven months. For eight months of that time she was in the waters of Chili and Peru. While in Chili, the bottom of the ship was cleaned by divers belonging to the crew of the ship. The whole of the bottom was cleaned once. The forward third of the bottom was gone over a second time. The propellers were cleaned three or more times.
The Charleston, San Francisco, Boston, and probably others of our new vessels have used divers for cleaning the bottoms. The Chileans have for years used divers for cleaning the bottoms of their vessels. I have been unable to find anything published on the subject, and think that an account of the method used on the Baltimore may be of interest; and hope that other officers who have had experience on this subject, or who may have given any thought to it, will give their views on it.
The Baltimore was docked at Toulon, France, in February, 1891; and the bottom was painted with McGinnis' paint. Immediately afterwards she sailed for Chili, and arrived at Valparaiso about the 1st of April. She remained in Chili and Peru until the middle of December, when she sailed for San Francisco, and was docked at the Mare Island Navy Yard in January, 1892.
Within four or five months after arriving in Chili, the ship began to lose her speed on account of foul bottom; and it was decided to clean the bottom with divers. There were on board, in the crew, two seamen gunners who had qualified as divers at the Torpedo School at Newport, besides Mr. Peter Hanley, the gunner, who had also taken the diving course at Newport; and who had general charge of the diving gang while the work was being done. The sailing launch was used for the pump. In a safe and smooth harbor, a scow, or camel, would be better. But at Valparaiso we had to use the launch. Several of the thwarts were unshipped, and the pump was lashed to the bottom boards of the boat. An iron ladder was secured on the side of the launch, next to the ship, for the use of the diver in getting into the water, or into the boat when he stopped work. One of the iron ladders, taken from one of the ventilators on deck, was used. It was about ten feet long, two feet wide, and was curved at the top so that it hooked over the gunwale of the launch, well aft. It was fitted with iron braces that fitted up against the side of the launch, under the counter, and was held rigidly in a perpendicular position. For use under the ship, a wide Jacob's ladder was made on board. The sides were of 3-in. manila and were about 20 fathoms long; or long enough to reach from the spar-deck under the ship, and up to the deck on the other side. There were 10 rungs, placed 18 inches apart, and every other rung was weighted with old grate bars, lashed to it. The rungs were of pine boards, 10 feet long, 4 inches wide, and 2 inches thick. While cleaning the bottom the diver was always on this ladder, or between it and the ship's bottom; and he would stand, sit, or lie down on the ladder, as was most convenient for his work. The pump and diver's dress were those supplied to the ship in her outfit.
The scrapers used were of wood (either oak or ash), and were made in the shape of a wide chisel. They were about 4 inches wide and 8 inches long, the handle end being rounded down. A number of them were made by the carpenter, and they were kept sharpened, or trimmed down, like the edge of a chisel. They were pushed before the hand, like a chisel, rather than being pulled like a scraper.
The diver chose the man who attended the life line. This important duty should be done by a practical diver. On the Baltimore, it was done by the other diver. Four men were in the launch besides the man who attended the life line. Two of these worked the pump, and the other two attended the bow and stern lines of the launch, and would relieve the men at the pump every half hour. Four men were required on deck, to attend the lines, lower and haul up the ladder, and shift it when necessary.
The general routine for the diving work was as follows: The sailing launch's crew would lower the launch, and haul her alongside, where needed. Four men from the working division for the day would go in the launch, and four other men from working division, generally under charge of one of the gunner's mates, would be on deck, to get the Jacob's ladder in position, and attend the lines, while the work was going on. The diver, and the man who attended the life line, would go in the launch, and the diver would put on the diving suit, except the helmet. The iron ladder would be hung over the launch's side and secured. The launch dropped or hauled to right position, and secured by bow and stern lines. The Jacob's ladder would be hauled so that the upper rung was just awash. The diver would stand on the iron ladder, the helmet be put on, the lines, hose, etc. , adjusted and the pump started. The diver would go down, get inside the Jacob's ladder, and start the work with his wooden chisel. He would clean a fleet ten feet wide, and when ready, would signal to lower the ladder. When the fleet was finished to the keel, he would signal, slack off (say) port and haul up starboard. The ladder would be pulled up by the men on the deck, with the diver on it. When his helmet appeared the ladder would be shifted aft, with the diver on it, and he would start in on another fleet. He always worked from the water line, down. When the time came to stop the work for the day, the diver came up, got on the iron ladder, and was helped into the launch, and took off his diving suit. The boat was dropped under davits and hooked on and hoisted, and, in this particular case, was generally rigged in and secured in her cradle, the pump being left in her. The lines on deck were hauled taut, and left under the ship for the night.
The two divers worked on alternate days, and they were limited to five hours a day; as it was thought that, in the cold waters of Chili, more than five hours a day would be bad for their health.
The divers were allowed $1 per hour in addition to their regular pay. They were allowed 15 minutes in each hour for a breathing spell. But after a little experience, they did not take this spell, and would often remain down at work two, and even three hours without coming up. If they took the 15 minutes in each hour, the time was not deducted; but if they did not take it, they were not credited with that much more time. The time taken to clean the bottom once, and to clean one-third of it a second time was a little over two months. The actual number of hours of diving work, as taken from the Paymaster's vouchers, was 200 hours 14 minutes. This time includes all the diving done during three months. The propellers were cleaned several times; the Kingston and other valves cleaned, and a third of the bottom was gone over a second time. So that it would be fair to say that the bottom was cleaned the first time with 150 hours of diving work. This work was done under adverse circumstances, in the exposed harbor of Valparaiso. Often a sea would make, and the work would have to be stopped within an hour after it was begun.
The launch was hoisted every night, and the ship kept ready for getting under way at short notice. As the men became accustomed to the work, they became very expert at it, and did much more work at the last.
The barnacles on the bottom of the Baltimore the first time she was cleaned, averaged about 2 ¾ inches in length. Some of them were 3 inches long. They were often in clusters, so that they extended six inches or more from the ship's bottom. These large barnacles were difficult to get off, and they generally took off three coats of paint with them; the McGinnis green, the brown, and a coat of red lead. A great many of them were examined, and I am of the opinion that they did not take the inner coat of paint, and the cement paint with them: so that at that size I do not think taking them off exposed the metal. When going over the bottom the second time, the barnacles were of about six weeks' or two months' growth, and were about ¼ to ½ inch long. These brought off with them only one coat of paint, the green.
After the bottom was cleaned, the gunner made an inspection, and reported that it was well done. When the ship was docked at Mare Island, it was seen that the work had been faithfully done. The line up and down the ship's bottom, showing where the last fleet had been cleaned the second time was as clearly defined as if the cleaning had been done in dry dock. On one side of this line, the bottom was practically clean. On the other side were barnacles of about three months' growth, about ½ to ¾ inch long.
The vessel suffered no serious loss of speed through having a foul bottom.
From the experience on the Baltimore, I think that two divers, working, each on alternate days, can, after a little practice, in warm water, and where the barnacles have not more than three months' growth, clean the bottom of a 5000-ton ship in from 120 to 140 diving hours, or at six diving hours a day, in from 20 to 24 days. And if it were necessary, each diver could work five hours a day, or ten hours total per day; and they could clean the bottom in two weeks.
And if a ship is so placed that she cannot be docked, the cleaning should be begun at the end of three months, when the barnacles are small, and come off easily, and do not bring off much paint with them; and the cleaning should be repeated every three months. This can be done with her own men, at a cost of $600 or less per year, and the ship can be kept so that she will suffer no serious loss of speed on account of her bottom.
In addition to this, the divers, diving suits, pumps, etc., will be ready for use and kept in order, so that if the diver should be needed to make repairs, etc., he will be in practice, and the apparatus ready.
The objection that may be urged to cleaning the bottom is, that the barnacles take off the paint, and thus expose the metal to the water, and that pitting may take place. When the Baltimore was docked at Mare Island, I was not able to detect any pitting from that cause.
My opinion is that a vessel can be kept practically clean, and suffer no serious loss of speed, and not be injured by pitting, for at least a year, by the use of her divers, at a cost of $600 for labor, about $70 for two new diving suits, and the original cost in outfit of about $600 for the pump. The pump should, with care, last indefinitely, 15 or 20 years.
DISCUSSION.
Rear-Admiral Daniel Ammen, U.S.N.—The explanation of the process of cleaning the bottom of the Baltimore is very clear. The so-called harbor of Valparaiso is only a roadstead with deep water for anchorage, subject to heavy swells and high winds liable to greatly embarrass such work.
Some years ago, a friend brought to my notice an invention of Mr. Freeborn, designed to cleanse ships' bottoms by means of petroleum. I brought him in communication with the Navy Department, and understood that he was offered an opportunity of trying it on a tug at Boston, but am without further information on the subject.
It seems to me that it might prove of advantage to endeavor to prevent the fouling of ships' bottoms; and this could readily be done with the means used in cleaning the bottom of the Baltimore. After a voyage, I suggest thinning coal tar by means of adding as large a quantity of crude coal oil or haphtha, as may be found necessary, and adding to the mixture, mechanically, a certain amount of London purple. A large funnel with a stop-cock could be hoisted or lowered on board the vessel to secure the desired rate of outflow of the liquid through a hose and a suitable "rose," as on a watering pot, to spread the fluid. The diver could begin forward on the line of the keel, and the current would tend to sweep the liquid aft, while the specific gravity would cause it to rise towards the surface, and as the coal tar is very sticky, even under water, a thin coating might be formed, after some practice in distribution, over the entire bottom of a material that would perhaps kill animal and vegetable growth, and delay further formation for a time.
A trial would not be troublesome or expensive, and the effects would be readily ascertained. It is supposed that dead barnacles and grass fall off. If that should not occur, the diluted coal tar might delay for a time a further growth, and thus render less frequent the necessity of cleaning the bottom by the process of scraping.
The following is a portion of Mr. Freeborn's reply to a request for further information on the subject; it was received after the above discussion was written:
Admiral Ammen, Ammendale. Md.
Dear Sir:—In answer to your inquiry I would state that on account of ill-health I have made no experiments since 1891, three years this summer.
The last applications I made in 1891 were only partially successful, in consequence of the vessels lying in port for some time before applying the oil, the foul water from the sewers in the docks having killed the barnacles. The cement attaching them having set, the oil had no effect on the dead ones.
The following conditions are necessary to insure success, namely:
- The barnacles must be alive, and the application made before a second crop attach themselves in sufficient numbers to kill those already adhering to the vessel's bottom.
- An application should be made every three months.
- The application must be made at sea and before entering harbor.
- The vessel should be put to her full speed immediately after the application.
I have not been able to make a trial under the conditions stated, but have full faith that success would be the result.
I send you copy of the English patent, as I find that I have no copies of the American patent with drawings attached; also, find copy of letters from Brazil Mail Steamship Co. In the mentioned cases the vessels were covered with grass, slime, and a barnacle different from the ordinary one.
I intended to start in May to renew trials of the invention, my health being sufficiently restored to superintend the application of the oil during the summer months.
A good plan would be to meet a man-of war on some West India, Central American, or even South American station after three months cruising. After applying the oil, the speed of the vessel, under the same pressure of steam before and after, would indicate the success or non-success of the invention.
I will be pleased to give you any further information which I may have, or answer any questions, should you so desire.
Most respectfully, Wm. Freeborn.
Lieutenant-Commander B.F. Tilley, U.S.N.:—I appreciate the practical manner in which Mr. Sebree has presented this subject. It is a matter of great importance. The ability to clean a ship's bottom with her own divers means that it is possible to restore to her at any time her approximate full speed without docking, and without outside aid. It can easily be imagined that, in the operations of actual war, this power would be invaluable. With our unsheathed ships, even a slight fouling of the bottom causes great decrease in speed, and in tropical waters the fouling progresses very rapidly and the loss is enormous. Even under the ordinary conditions of cruising, in times of peace, cleaning the ship's bottom might enable her to make a passage otherwise impossible, and, in an extreme case, might thus save the ship. It often happens that our new ships are not docked for a full year. The Philadelphia, now at Honolulu, has not been docked since June, 1893. The Boston remained out of dock for about the same length of time, and with several other new ships the exigencies of the service on which they were engaged have prevented them from being docked for eight or ten months. If it were not possible to clean the bottoms of ships with divers, I do not think that, after being so long in tropical waters, a twenty-knot ship would make over sixteen or seventeen knots, and there would be difficulty in maintaining even that speed. The experience on board the San Francisco, while I was attached to her, confirms what is stated by the writer to have been practicable on board the Baltimore. After a little practice, we found that the ship's divers were able to clean the ship's bottom in about the same time and at about the same cost as is given for the Baltimore in this article. The procedure on board the San Francisco was similar to that on board the Baltimore, but instead of using an iron ladder taken from the deck, an iron ladder was made especially for the purpose. This ladder was fitted to hook over the stern of the sailing launch, and to project a little from the boat. While the divers were at work a red danger flag was always displayed from the boat where the pump was worked, to prevent tugs, etc., from running near. On many occasions, when it was not desirable to clean the ship's bottom, the propellers and sea-openings for valves were cleaned by the divers. When the divers were working on the propellers it was found most important to inform the chief engineer and the engineer on watch, so that the engines could not by any chance be turned. A neglect of this precaution might easily cause the diver to lose his life. It should be a part of the "routine." The diver being always in a perilous position, it appears to me that the system of signals used on board the Baltimore was too complicated. I think that there should be but a few simple signals, and that the safety signal, "pull me up," should be one pull on the life-line, so that the diver, even if panic-stricken or injured, would make it almost involuntarily.
As to the compensation for divers, I think that the extra fifteen minutes in each hour for breathing spell should always be allowed in computing the amount due them, even if they do not come up to breathe. This liberal treatment would encourage them, and, at the most generous estimate of their work, they receive far less compensation than divers in civil life receive for the same service. This applies especially to the occasions when they work for only a few hours, as in cleaning the propellers, where, with the breathing time allowance, the amount received for the risk and labor would not be more than four or five dollars. When a ship is fitting out, I would suggest that the executive officer exercise great care in regard to the diving apparatus supplied. Both the pumps and diving suits should be tested before leaving a navy yard, and no inferior article should be accepted. It is economy for the Government to have all the articles of the very best quality. I make this suggestion because, on going to sea in the San Francisco, I found that the ship had been supplied with old diving suits which had been repaired. They began to leak as soon as we used them and the divers were wet and uncomfortable while at work.
While I regard it as so important that a ship should be able, with her own resources, to clean her bottom, the risk of taking off the paint with the barnacles, and thus exposing the bottom to rust, is too great to warrant doing it unless it is very necessary to increase her speed. It should not be done habitually to save coal in ordinary cruising.
Lieutenant-Commander W.T. Swinburne, U.S.N.:—I am glad to add the testimony of my experience in the Boston to Mr. Sebree's on so important a subject as the preservation of the cruising qualities of a modern ship on stations where docking facilities are few. This has been shown to be particularly the case on the Pacific Station, and the experiences of those on the Baltimore, and other ships on that station, would seem to show that, with a little care, the speed of a ship can be kept intact for an indefinite time, with but little danger to the bottom.
During the time I was attached to the Boston, in the harbor of Honolulu, from August, 1892, to May, 1893, the ship's bottom was cleaned by the ship's divers twice. The methods we employed were almost identical with those described by Mr. Sebree. The two trysail ladders from the main mast, lashed end to end, were used under the bottom, oars were lashed across them, about four feet apart, to give a wider support for the diver, the lower point was weighted with grate bars, and the whole raised or lowered by tackles from the awning ridge rope on either side of the ship The diver, partly lying and partly sitting on the ladder between it and the ship's bottom, using a coir clamp brush, with a handle about six feet long, was able to clean a streak about ten feet wide, from waterline to keel at each fleet. We had two divers, one working in the forenoon and one in the afternoon. As they gained experience, the work required no supervision from the officer-of-the-deck, and interfered with none of the ship's routine.
For details, I must refer to Lieutenant Laird, who was senior member of the Quarterly Board of Inspection during the time referred to, and who was present when the ship was docked, on her return to San Francisco, and who can quote accurately from the very admirable records he kept of his various inspections.
Lieutenant Charles Laird, U.S.N.:—Mr. Sebree, in his paper, has called attention to a subject of the greatest importance.
It has been shown in the last three years in the cases of the Baltimore, Boston, Charleston and San Francisco, that, with the limited docking facilities on the west coast of America, some method should be pursued for the care and preservation of the under-water body of ships, which, through stress of circumstances, are compelled to remain out of dock for an extended period of time.
That the ship's bottom can be kept comparatively free from animal and vegetable growth, by the work of ships' divers, has been definitely settled.
I desire to call your attention to the case of the Boston, during her last cruise. The condition of the under-water body was reported upon by the permanent board at the time of docking at Mare Island, in May, 1892, and again at the same place, in October, 1893, an interval of one year and five months. During the greater portion of this time the ship was moored in the harbor of Honolulu, and the conditions were such as to be favorable to a rapid growth of submarine matter on her under-water body.
Quoting from the journal kept by the permanent board, and from the quarterly reports made by that board:
"The ship was docked in the Navy Yard, New York, October 1, 1891; the starboard side was painted with McGinnis and the port side with germicide paint."
When the ship was again docked at Mare Island, May 26, 1892; "It was surprising that the under-water body should be so free from vegetable growth. During the cruise in southern waters, this growth accumulated with great rapidity about the waterline, and, as far as could be seen on the under-water surface, it adhered with the greatest tenacity, and was with difficulty removed, when it was possible to list the ship for scraping and repainting the exposed surface. That this vegetable growth had disappeared, may be due to the fact of the ship having been alongside of the dock at the Navy Yard, from the 4th to the 25th of May, in water more or less fresh, and that, together with the great amount of sediment in the Napa River, may have tended towards its removal.
"The most marked evidences of deterioration were found in the bottom blow-pipes, the rivet heads being so much eaten away by the salt water as to necessitate removal. On the keel plates were found evidences of pitting, but none of a serious nature; more pits were found at and about the waterline than at any other portion.
"The paint applied to the bottom whilst in dock was as follows:
First coat, 2/3 red lead, 1/3 zinc.
Second coat, 1/3 red lead, 2/3 zinc.
Third coat, pure American zinc.
Fourth coat, pure American zinc.
An interval of two days between each coat was allowed, in order that the paint should dry thoroughly."
From May, 1892, to October, 1893, when the ship was next docked, the bottom was cleaned three times by two men of the ship's company, working as submarine divers.
This work was done in the harbor of Honolulu; the same general plan was followed as that described by Mr. Sebree.
The ship's bottom was first cleaned by the divers during the quarter ending December, 1892.
The divers reported the condition of the ship's bottom as follows: "A rough surface of grass about 1 ½ inches long, about the bilge, and grass 6 inches long, hanging to the bottom." For the removal of this growth the divers used the ordinary bristle clamp brushes, fixed to handles about 6 feet in length.
Two specimens of the growth were taken at different points, for the purpose of getting an approximate idea as to the accumulated weight on the ship's bottom. The grass taken from one square foot of surface on the port side weighed eleven ounces, and that taken from an equal area on the starboard side weighed ten and one-half ounces.
In June, 1893, whilst the ship was at anchor in the harbor of Lahaina, Maui, an inspection of the under-water body was made with the aid of a water-telescope. The general opinion of the board was that the paint was adhering well, and that there was no marked evidence of deterioration.
In the clear water of this harbor an excellent view of the ship's bottom was obtained. It was conclusively shown that the work of the divers had been well done.
During the month of April, 1893, the ship's bottom was again cleaned, the same method being pursued.
There was a marked change in the character of the growth on the ship's bottom. The vegetable growth had disappeared, and in its place was found an animal growth, covering the entire under-water surface from 2 feet below the water-line to the keel. The growth adhering to the ship's bottom was firm and tough, resembling cartilage; one specimen brought up by the divers was 15 inches in length, 6 inches in width, 2 ½ inches in depth, and weighed 3 ¾ pounds; the scale of oxide of iron adhering to the under surface was 5-32 inches thick.
The divers worked during this month 113 hours.
In August, the ship again visited Lahaina, for target practice. An inspection was made at that time with the aid of the water-telescope, and the divers' work found to be well done. Places on the keel, reported as being in bad condition, could be plainly seen.
The ship's bottom was again cleaned by the divers in September, 1893, the total time for work being 71 ½ hours. In cleaning the bottom at this time, iron chisel scrapers, fixed to handles about six feet in length, were used. The character of the growth had again changed. The divers reported the bottom as being covered with a growth of needle coral, the needles being from 1 to 6 inches in length.
Upon the return to the coast, the ship was docked at Mare Island, October 20, 1893.
Quoting from the report of the quarterly board: "In general, the paint was found to have adhered well, but was worn and abraded in places. Little or no vegetable, and but little coralline growth was found, except in the unavoidable holidays left by the divers.
"On the hull there were but few evidences of pitting; clusters from 1 ½ inches to 6 inches in diameter were found, but in no case were the pits of greater depth than 1-16 of an inch.
"On the propeller there were two clusters of small deep pits, near the edge of diametrically opposite blades, on the reverse side, near the entering edges. The other blades were free from pits.
"Numerous rust spots of inappreciable depth, isolated and in patches, were found; the patches varied from ½ to 6 inches in diameter." Beneath the paint, no matter how well preserved and adherent, a jet black oxide of iron was found.
That the ship was kept in a more efficient state as to speed and economy in the use of fuel by these repeated cleanings, there can be no doubt, nor was this done at the expense of the ship's bottom. Should this submarine matter have had an uninterrupted growth during the months the ship was in southern waters, the result would, in all probability, have been much more serious.
The water-telescope aided so materially in the inspection of the ship's bottom, in the clear water off Lahaina, that I add a description of its construction, together with the use made of it in an attempt to take a photograph of the after-run and propeller.
A rectangular box, 1 foot by 1 foot by 3 feet, was constructed, the joints of which were water-tight. One foot from the lower end a plate of clear glass was set within the box, rabbeted to the wood, so as to make the joint watertight. As close as possible to the under-surface of the glass, holes ¼ inch in diameter were bored through the box, to permit the air-bubble to be excluded. Handles were fitted on opposite sides, one foot from the upper end; the lower end was weighted with sheet-lead, to reduce the buoyancy, and the inside painted white, to reduce the absorption of light.
It was found that, in comparatively smooth water, the telescope could be readily handled in the dingy; and, that a very clear idea could be gained as to the manner in which the divers had performed their work.
An attempt was made to photograph the propeller and after run of the ship.
Assistant-Surgeon Thomas C. Craig, a photographer of some experience, made the attempt, the failure of which was due to lack of time, and the sea becoming so rough as to endanger the camera.
In attempting to take the photograph, the following plan was adopted: Battens were nailed on the inside of the telescope, on which the camera rested, with the lens one inch clear of the glass of the telescope. The admission of the light to the lens, from the back of the camera, was entirely cut off.
The camera fixed in the telescope, was focused on an object sixteen feet distant, that being about the distance of the keel from the water-line; the whole was then taken in a boat, the lower end of the telescope submerged, and directed towards the after-run. The picture, as seen on the focusing glass, was clear, sharp, and distinct. At this time, however, the sea became so rough that the experiment had to be abandoned.
Commander G. A. Converse, U.S.N. (Inspector of Ordnance, Torpedo Station, Newport):—(1). The regular course in diving, at the Naval Torpedo Station, embraces three weeks of practical work, during which the men are taught, (a) how to handle the air-pump; (b) to dress a diver; (c) to communicate and receive signals to and from him; (d) diving in shoal water; (e) diving in deep water. In addition to this course of instruction, they have, during the time they are here, a great deal of practical work to perform: for example, during the last summer they put down an extension, one hundred feet long, to the ways for the Cushing, doing all the work of scarfing the ways, aligning, putting on the iron straps, etc., under water, and so well was the work performed that not a single hitch occurred the first time the cradle was run down, and the Cushing put in place at the lowest of neap tides. More recently, they have worked for three successive days, in upwards of fifty feet of water, with the temperature of the air nearly down to freezing, and successfully raised a submarine boat, displacing approximately 10,000 pounds. They also, last month, did work on the bottom of the training-ship Portsmouth.
(2). The telephone has not been used to any extent, either here or abroad, so far as I am aware. Many devices have been made, and some of the experiments are reported as successful; I believe those made in Germany. I have had consultations with some of the prominent wreckers in regard to the matter, and they all seemed opposed to its use. One objection seems to be that, in almost any form in which it has yet been proposed to use it, it simply adds one more line and one more chance for the diver to become entangled. Another is that the present means of signaling seems to answer all requirements; and still another objection, in my opinion the true one, is an evident disinclination on the part of those who are under water, and on the spot where work is to done, to be bothered or to be obliged to receive definite instructions from those who are attending them from the deck of the vessel, who can, from the nature of their position, know little or nothing of the details of the work which they cannot see. In this opinion, I must agree that the diver, to be a successful workman, must be "boss" of the situation, and the duty of those who are attending him must be simply to supply him with air, according to his directions, carry out the instructions which he has previously given them, and to guard against any accident happening, whereby his safety may be imperiled.
(3). The usual signals employed are as follows:
Two pulls on the life-line and two on the air-pipe, in rapid succession, indicates that the diver is foul and cannot free himself. On receiving this signal no attempt should be made to haul him up, but his signal should be answered and another diver sent down to release him.
(4). Regarding the cost of a diving suit:—A complete diving apparatus, including pump, helmet, hose, weights, etc., etc., and two pairs of diving dresses, costs about $600. After the outfit is once purchased it is really necessary to procure no supplies other than dresses, which cost about $35 each, snap-tubing, etc. Our apparatus at this Station has been in use from 15 to 20 years, and the pumps are still in good condition. As a rule, we obtain two diving dresses a year, this being necessary on account of the extreme wear and tear caused by the frequent dressing and undressing made necessary by the course of instruction.
(5). We have not yet published anything in regard to instructions to divers, but one of the officers has the preparation of a handbook on diving under way, and it is my intention to have it completed and published during this Spring. Some of the principal features which I desire to embody are illustrations of pumps and various articles of outfit.
(6). As a rule, we get all of our apparatus from Alfred Hale & Co., of Boston, Mass., having started out with them and finding it desirable to always obtain articles which will fit the apparatus which we have on hand. Andrew Morse & Son, also of Boston, make good apparatus, as do also two or three firms in New York, one especially, by the name of Schroeder, if I mistake not, who supplies largely to the Merritt Wrecking Co. We have also a complete suit of English apparatus made by Siebe & Gorman, the pump being intended to be used with two divers if necessary. Our experience with this has been, however, that unless both divers are working at the same level, the one nearest the surface is apt to get the greater part of the air at the expense of the poor fellow who happens to be under him. Still, it works.
I am glad to learn of the success in keeping the bottom of the Baltimore clean, and also that the Boston was able to do the same. Capt. Sampson told me last summer that he cleaned the bottom of the San Francisco with the divers and believed there was no difficulty whatever in keeping vessels of that class in good steaming condition with their own crews and a comparatively inexpensive diving outfit.
It is particularly pleasing to me to know that the instruction which has been given to these men at this Station is at last bearing fruit. A change of sentiment seems to have come over the men, as well as over the service at large. Now those who are here qualifying for seamen-gunners, without exception, unless absolutely forbidden by the Surgeon, qualify as divers, and seem to like the work. It is the usual thing when a detail of men is wanted for deep water diving, to have more volunteers than are required for the work, and this too, when at this Station they are not allowed extra compensation for any work however important and even supplementary to the course of instruction.
In the operation of raising the submarine boat a few days ago, our instructor in diving was ill, and the officer who has regular charge of that branch of instruction was absent on detached duty. The entire operation was successfully performed by the men, of course under the general supervision of an officer.
Some of the wrecking vessels are fitted with air-pumps worked by steam. and I saw one in use not very long ago, similar in appearance to the small donkey pumps used on board ship, which could not have weighed more than 250 pounds.
I think that the day is not far distant when all of our vessels will be fitted with a pump of similar description, located at some convenient place amidships, so that the length of hose required for those engaged in cleaning the bottom need not exceed, at the utmost, 200 feet.