The Admiralty’s committee on deep diving kept a diary of its sea trials in the Firth of Clyde in August 1906, and printed it in its report of 1907. Boycott, Damant and Haldane reprinted it the following year as the second appendix to their paper in the Journal of Hygiene, and Leonard Hill printed most of it again in 1912. This piece follows it day by day, with the times and depths as the diary gives them, and with the chamber trials in London that came first. The committee’s own report has not been reached; everything here is from the two reprints.

July: the chamber

Before any diver was taken through half his pressure under water, the schedules worked out on the goats were tried on the two men who would dive. “These experiments were undertaken in July, 1906, as a preliminary to actual diving experiments in very deep water.” The subjects were Lieutenant Damant and Mr A. Y. Catto, Gunner, Royal Navy. In the first three or four the decompression was controlled from inside the chamber, afterwards from outside. After each experiment the two men stayed shut in the chamber for half an hour with the engine running, so that if either showed a serious symptom the pressure could be put back on at once.

The seven experiments, with the actual time at pressure, the “virtual” time (which adds half the time spent compressing), and the time taken to come out by stages, were:

• 25 July: 39 pounds for 60 minutes (virtual 69), out in 24 minutes.
• 26 July, at 10.37 a.m.: 50 pounds for 27 minutes (39), out in 34.
• 26 July, at 3.03 p.m.: 55 pounds for 19 minutes (33), out in 31.
• 27 July, at 10.29 a.m.: 60 pounds for 20 minutes (36), out in 37 and a half.
• 27 July, at 3.37 p.m.: 67 pounds for 18 minutes (36), out in 36.
• 30 July, at 10.57 a.m.: 74 pounds for 15 minutes (35), out in 42.
• 31 July, at 11.00 a.m.: 80 pounds for 12 minutes (34), out in 51.

Eighty pounds above atmospheric is six and two-fifths atmospheres absolute, a little more than the pressure at 180 feet of sea water. “In view of the results with goats, the occurrence of decompression symptoms seemed probable in the more severe experiments. No symptoms were, however, observed, except considerable itching of the skin of the fore-arms where it was uncovered. In the compressed air the well-known alteration in the voice, and corresponding abnormal sensations about the lips and mouth, were very marked at pressures exceeding 60 or 70 lbs.”

Monday 20 August

“H.M.S. Spanker arrived at Rothesay about 7 p.m., and was met by Drs Haldane and Rees and Mr Catto, Gunner, R.N. Arrangements were made to commence experiments the following day.” The Spanker was a torpedo gunboat of 1889, with a deck about eight feet above the water, so that a diver coming out had to climb eight or ten feet of ladder in his full weights, 155 pounds in all, before the 40-pound breast and back weights were taken off him. Hill thought this climb “must have materially aided the desaturation of the body.”

Tuesday 21 August

The day went on the apparatus. “All the pumps to be used in the experiments were tested up to a pressure of 200 feet, and the leakage at this pressure measured.” The method was to tie the free end of a diving hose to a lead-line, lower it over the side to the depth wanted, heave the pumps round until the air came freely, and then stop them and read the gauge. The gauges, “specially graduated for these experiments,” read true. The recompression chamber for the deck was tested on the ship’s Whitehead torpedo charging column: 40 pounds in three minutes, with a leak of a pound a minute. “Afterwards Drs Haldane and Rees were compressed up to about 30 lbs. in order to further test the working of the chamber.”

In the afternoon both divers went to fifteen fathoms, 90 feet. Damant went down in two minutes, stayed an hour, and came up in eighteen and a half minutes with two stops; Catto went down in a minute and a half, stayed an hour, and came up in seventeen and a half with two stops. Two double pumps were used for each diver in these and all the later dives. “The divers were perfectly comfortable in moving about on the bottom.” The diary then records the two men’s experience. “Lieutenant Damant had not dived previously beyond about 19 fathoms, and had no experience in diving except what he had gained in his course of instruction as a gunnery officer and in experimenting at Portsmouth for the Committee. Mr Catto had much previous experience in diving work, but had never dived beyond 23 fathoms.”

The divers were connected to the deck by telephone, which the diary calls a convenience “particularly when samples were being taken, or work experiments carried out, and when one of the divers got foul.” The ascent was run from the deck. The diver was stopped at each stage by a signal on his breast-rope. The man at the gauge watched the depth come up; when it was within ten or twenty feet of the next stop the pumps were stopped and the gauge tapped, because with the pumps going the resistance in the pipes made the gauge read several feet deep, and when it showed the right depth the diver was signalled to stop. “There was never the slightest difficulty in stopping him at the right point within a foot or two.” The gauges were graduated for fresh water; a diver sitting on the bottom at just over 35 fathoms, 210 feet of sea water measured on the shot-rope, showed 216 feet with the pumps stopped and 220 with them going, and “a pressure of 216 feet of fresh water corresponds almost exactly to 210 feet of sea water.”

Wednesday 22 August

Off Rothesay. Catto in the forenoon and Damant in the afternoon went to twenty-three fathoms, 138 feet, two minutes down and twenty minutes on the bottom. Catto came up in thirty-five and a quarter minutes, with four five-minute stops at 50, 40, 30 and 20 feet and ten minutes at 10. Damant came up in thirty-two and a half, with five-minute stops at 50 and 40 and ten minutes each at 20 and 10.

Thursday 23 August

Off Rothesay. “After testing the pumps each diver made a descent to 25 fathoms,” 150 feet. Damant: two minutes down, eighteen and three-quarters on the bottom, thirty-seven and a half up, with three five-minute stops at 60, 45 and 30 feet and ten minutes each at 20 and 10. Catto: two minutes down, three five-minute stops at 50, 40 and 30, and two of ten at 20 and 10. Damant then went again: down in one minute twenty seconds, sixteen and three-quarter minutes on the bottom, forty-four and three-quarters up, with four five-minute stops at 60, 50, 40 and 30 and two of ten.

Friday 24 August

“H.M.S. Spanker was taken through the narrows of the Kyles of Bute and anchored off the entrance of Loch Riddon.” In the morning Catto went to twenty-seven fathoms, 162 feet: two minutes down, sixteen and a half on the bottom, fifty-five and a half up, with five-minute stops at 60, 50, 40 and 30 and one at 20, “the diver was employed just under the ship’s bottom in examining a propeller which had been slightly injured, for 19½ minutes before coming up.” Damant went to the same depth in the afternoon.

Saturday 25 August

Off Loch Riddon, the ship shifted a little, and both men went to twenty-nine fathoms, 174 feet. Catto: three minutes down, fourteen and a half on the bottom, forty-six up, with five-minute stops at 70, 50, 40 and 30 feet and ten minutes each at 20 and 10. Damant: a minute and a half down, thirteen and a half on the bottom, forty-eight and a half up, with five-minute stops at about 60, 54, 40 and 30 and ten minutes each at 20 and 10.

Monday 27 August

“Thirty fathoms of water were obtained,” thirty and a half by the lead-line. Catto dived in the morning. Pumps 3604 and 3593; six men to each pump in reliefs of five minutes. The diary gives the descent minute by minute. Glass screwed up at 11.22; under water at 11.23 and a quarter; 50 feet, 70, 110, 150, and at 11.24 and three-quarters “180 feet, on the bottom. 1 min. 30 secs. in descending.” The pumps averaged thirty-two revolutions a minute “but fell to 24 for a short time, owing to the great exertions that were necessary to keep the pumps going at the higher speed. Diver quite comfortable while moving about on the bottom.” Called up at 11.36 and a half; started up at 11.38 and a half; 160 feet at 11.39; then 140, 120 and 100; and at 11.46 and a half the first stop at 70 feet, where the diary notes “Diver employed in gymnastic exercises. One pump stopped.” Then 50 feet at 11.51 and a half, 40 at 11.56 and a half, 30 at 12.01, 20 at 12.11, 10 at 12.11 and a half, and called up at 12.22 and a half, glass off at 12.23 and a half. “There were no ill-effects. Water jackets gained 20 degrees F.”, which is to say that the cooling water round the pump cylinders had warmed twenty degrees with the work of pumping.

Damant in the afternoon. Glass screwed up at 2.14 and three-quarters; under water at 2.15 and three-quarters; 70 feet at 2.16; 120, 160; “186 feet on the bottom. 1 minute 20 seconds in descending. Revolutions averaged 30 per minute.” Called up at 2.29; started up at 2.30; 170 feet at 2.31; 120 at 2.33, where he stopped a minute and a half; 70 at 2.33 and a half, the first stop; 50 at 2.38 and a half; and then stops at 2.43 and a half, at 2.48 and a half, at 2.53 and a half, at 3.03 and a half and at 3.13 and a half.

Tuesday 28 August

In the afternoon Catto was in the dress, with pumps 3588 and 3592. Glass screwed up at 2.17; 60 feet at 2.18 and a half; 100 at 2.19; and at 2.19 and a half “180 feet, on the bottom. The diver took down with him a wire hawser to shackle on to a sinker.” At 2.31 and a half “Diver called up, but could not come up, as he was foul,” and at 2.48 and a half he started up. At 140 feet at 2.50 and a half; the first stop at 100 feet at 2.53; then 80 at 2.56, 60 at 3.01, 50 at 3.07, 40 at 3.12, 30 at 3.22, 20 at 3.37, 15 at 3.52, 10 at 4.00, and on the surface at 4.18 and a half.

The diary explains. “Mr Catto attempted to shackle a hawser on to the sinker. He found the sinker without the slightest difficulty, and then, having tied his distance line to it, went back to the hawser. He found this in bights, and he seems to have got within the coils, and in trying to find the end of the wire to have fouled his life-line. When called up he could not get away, and it was twenty minutes before he could clear himself. In all he was down twenty-eight and three-quarter minutes in 30 fathoms of water. The rate of the pumps could not be kept up above 24 revolutions per minute, and the supply of air was not adequate to his exertions to free himself, so that he was almost overcome by the excess of CO2. On account of his long exposure during heavy work, great care was taken in decompressing him, one and a half hours being allowed. There were no ill effects.”

It is worth setting against the paper’s rule that in deep water a diver’s descent and the first part of his ascent should be as fast as he can make them. Catto had spent most of half an hour at six and a half atmospheres working hard and short of air, and was then given nine stops and ninety minutes, about three times what the table for an ordinary dive to that depth allowed. The length was a judgement, made on the deck, in the light of the goats.

Thursday 30 August

Off Loch Riddon. “Mr Catto made another descent under the same conditions, and shackled on the hawser to the sinker in four minutes after reaching the bottom. The revolutions of the pump averaged 24 to 30 per minute. The day was very bright, with the sun shining on the water, so that the diver saw with comparative ease in the water.”

Friday 31 August

“H.M.S. Spanker moved down to the entrance of Loch Striven, where 35 fathoms of water could be obtained.” Damant dived in the morning, with pumps 2593, 3604 and 3592, six hands to each in five-minute reliefs. Glass screwed up at 11.08; under water at 11.08 and a half; 80 feet at 11.09; 120 and 150 within the next half-minute; 180 at 11.09 and three-quarters; 200 at 11.10 and a quarter; and at 11.10 and three-quarters “216 feet, on the bottom. Revolutions kept at 30 per minute, and the diver had a good supply of air.” At 11.13 and a half “Diver took samples seated on the shot at the bottom of the rope.” Called up at 11.15 and a half; started up at 11.16 and a half; 190 feet at 11.17; 110 at 11.18, where he “stopped to blow off sampling tube”; then the stops: 90 feet at 11.20 and a half, 70 at 11.23 and a half, 52 at 11.28 and a half, 42 at 11.33 and a half, 32 at 11.39 and a half, 22 at 11.44 and a half, 11 at 11.54 and a half; called up at 12.04 and a half.

“There was no light on the bottom, which was of soft mud. The depth by the shot-line was 210 feet. Pressure was 93½ pounds. The gauge showed a pressure of 216 feet of fresh water with the pumps stopped, and 220 feet whilst they were heaving. The actual depth, as carefully measured on the shotted rope against the ship’s standard measure, was just over 35 fathoms (210 feet).”

“In the afternoon Mr Catto made the same descent, and reached 35 fathoms. He found that the air-supply was more than ample. He walked out to the end of his distance line, and then took a sample of the air in his helmet.” Glass screwed up at 2.12, with the same pumps; under water at 2.12 and a half; on the bottom at 2.14 and a half, where the pumps were slowed to twenty-four revolutions “as the diver found the supply too much.” Started up at 2.20 and a half; the first stop at 90 feet at 2.27 and a half; then 70 at 2.30 and a half, 50 at 2.35 and a half, 40 at 2.40 and a half, 30 at 2.45 and three-quarters, 20 at 2.50 and a half, 10 at 3.00 and a half; called up at 3.10 and a half.

What the samples showed

The bottles Damant filled while sitting on the shot were analysed afterwards. His resting output of carbon dioxide at 210 feet was the same as it had been in the experimental tank at Portsmouth, 0.014 cubic feet a minute; Catto’s was 0.013. On a sea bottom with a tide running, the figures rose to 0.022 and 0.016. In work they rose to 0.04 to 0.06, and once, when Catto had to struggle to free himself from mud, to 0.079. The committee reckoned that a diver at rest ought to have 0.63 cubic feet of air a minute, measured at his own pressure, to keep his helmet’s carbon dioxide under three per cent, and a diver at work 1.5, and that he must have that volume whatever his depth; the pumps must therefore turn faster in proportion to the pressure. At 210 feet with the pumps at thirty revolutions, both men had, by their own account, more air than they wanted.

The newspapers took the depth and left the arithmetic. The London Mail’s paragraph, which an American weekly reprinted in October, said the two men “have just descended a Scottish loch in diving suits to the depth of thirty-five fathoms, or 210 feet—a record for the British Isles and probably for the world, although greater depths are said to have been reached by the pearl divers in Australasia,” and added that the earlier records had been 189 and 192 feet by employees of Siebe, Gorman and Company, and that a diver who went to 204 feet “was killed by coming too quickly to the surface.” What the committee had actually found, it guessed at: “It is probable that it will be found that the chief precaution recommended by the naval committees now experimenting will relate to the preventing of the effervescing of the blood, and will lie in the direction of trying a slow ascent.” It was the opposite of what they had found.

Sources

• A. E. Boycott, G. C. C. Damant and J. S. Haldane, “The Prevention of Compressed-Air Illness,” Journal of Hygiene 8 (3), 1908, Appendix I (the chamber experiments of July 1906) and Appendix II (the diary, “reprinted from the Report of the Admiralty Committee on Deep Diving, 1907”). archive.org
• Leonard Hill, Caisson Sickness and the Physiology of Work in Compressed Air, 1912, pp. 50 to 53 for the carbon dioxide figures and the air-supply rule, and pp. 221 to 224 for the diary. archive.org
• “Dive of 210 Feet,” from the London Mail, in the New Hampshire Farmer and Weekly Union, 10 October 1906. loc.gov