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Captain Frank H. Schofield, Staff, Office of the Chief of Naval Operations Memorandum




October 8th, 9th and 10th, 1917.

     I visited New London October 8th and as I was taking boat from New London wharf to the Submarine Base, one submarine and three 110-foot submarine chasers were on their way to sea for practical experiments in command of Lieutenant Parker. . . .1


     At the Submarine Base I saw Professor Mason of the New London group, who explained to me somewhat in detail the experiments he was making in further development of the C-tube.2

. . . .I visited the school for listeners and found that most of the equipment already installed in the school could not be used owing to electrical difficulties which did not seem to be clearly understood by the people who installed the instruments or by the head of the school, Lieutenant Marsh.3 At present the principle thing <effort> at the school is directed towards familiarizing the men with the C-tube and towards exercising them in the use of the C-tube. Some dissatisfaction was expressed because no C-tube had been available at the school for preliminary instruction of arriving candidates for the school.

The Yacht WACCONDAH: Six C-tubes installed on each side and makes frequent trips to sea in company with submarine for the instruction of listeners.

A system of qualifications of listeners has been adopted which requires that men should be able to conn the yacht and determine the direction of submerged submarines which they cannot see to within an average area of 10 degrees. When the yacht goes to sea the conning of the vessel is done by the listeners at the forward C-tubes. None of the listeners are allowed to see anything outside the ship so that all of their predictions are made solely from the sounds that come through the C-tube. A careful record is kept of each observation of each man and compared with the actual bearing and distance of the submarine as determined at the instant by the observers on the bridge.

At present, the position of listeners at a C-tube, which necessarily hangs over the rail, clear of the side, is a cramped and uncomfortable position, difficult to maintain for any considerable period of time. In addition the stethoscope terminals of the C-tube are very irritating to the ears. I learned that after the stethoscope had been in the ears for as much as an hour that the sensation produced induces a high degree of nervous tension. This defect of the C-tube is now being looked into with a view to providing an equally efficient method of conducting the sounding waves to the ear drum without annoying the listener. Considerable progress has been made in this direction by using wax casts shaped to fit exactly the ear so that the sound can be conducted without loss direct to the ear drums. These casts when fitted to an ordinary telephone receiver headpiece are much more comfortable than the stethoscope terminals. Further experiments are in progress along the same line.

Lieutenant Parker, who is in charge of the tactical experiments with the submarine chasers and C-tubes, has had one C-tube installed through the keel of S C 6 in such manner that the listener is in a protected compartment, seated in a comfortable position. He states that this method of installation is far superior to the overboard type of C-tube and that a recommendation will be made officially that all submarine chasers be fitted with the keel installation of C-tubes.

Lieutenant Parker stated further that the experiments to date indicate that there would be no difficulty for three chasers to keep sound contact with a submerged submarine under favorable weather conditions, but that a rough sea would probably operate to preclude the use of the C-tubes effectively.

A recent class of 25 of our own men who took the course in C-tubes was made up of unsatisfactory material, although the men had been selected by psychologists among those available at the Naval Training Station at Newport, Rhode Island, but 4 of 25 of these men qualified as listeners. This fact taken in conjunction with the fact that 11 out of 12 Frenchmen sent to the school qualified in the same course, which indicated something seriously wrong with our men. After conversation with Lieutenant Marsh, I concluded, and he agreed with the conclusion, that the failure of our men to qualify was probably largely due to their lack of interest. The duty of listener on anti-submarine vessels is arduous and confining, and under present conditions somewhat disagreeable. Some means will have to be found to stimulate interest and to make men desire this duty. Men engaged in this duty are undoubtedly deserving of extra pay. I doubt if a satisfactory listener’s service can be maintained without the inducement of extra pay.

Another matter that reduces the efficiency of the listeners is their tendency to sea sickness. This is a subject of considerable importance. I recommend that no listeners be trained who are not proof against sea sickness in ordinary weather.


I visited the Commonwealth Pier at New London, which is now being used by the mined force and by some of the district craft. I saw Commander Johnson4 of the Dubuque and with him visited the pier and adjacent ground that has been leased from the State for the sum of $3,500.00 per month.

On the Dubuque Commander Johnson pointed out to me the fact that the mines carried by the Dubuque were unreliable and very largely ineffective. He stated that the Dubuque in its present employment had no military value as a vessel and expressed opinion that the Dubuque should be assigned to other duty, or else be given mines of a more reliable type. I gathered from conversation with Commander Johnson that he believed the Dubuque would be more useful during the present war if her gun battery was replaced and her mine laying equipment removed. . . .

The mine force has done a large amount of work in clearing and leveling the ground in the vicinity of Commonwealth wharf and now has the site to prepared that it seems to be exceedingly well suited to the rapid manufacture of anti-submarine nets.

There were about 1500 barrels and several hundred small sheet iron buoys at Commonwealth pier that had been purchased for use of nets, but had been found unsuitable. The barrels were worm eaten and beaten <leaky> and the buoys of such light construction that they collapsed when drawn under by the action of the tide on the net.

Commander Johnson spoke in very high terms of the Naval Reserves that are working and have been working on nets under his direction.

The new type of net which is proposed for the Block Island project is of exceedingly heavy material. Up to the present time, no nets of this character have been handled in this country. Commander Johnson stated that he thought it exceedingly important that several sections of this net be made up and “played with” with the idea of developing the best way of handling the net and of overcoming all the seamanship difficulties incident to its laying and subsequent maintenance.


     I talked with the Commanding Officer of the Fulton regarding respective duties of that vessel.5 He stated that the principal difficulty to be overcome was the lack of auxiliary power for the vessel. The Fulton has requested the assignment of a Diesel engine motor generator plant to that vessel to augment the present inadequate boiler power of the Fulton for auxiliary purposes. The Commanding Officer of the Fulton stated that the present boiler power of the vessel was insufficient to enable the Fulton to run machine tools and other auxiliaries that have to be used in the upkeep of submarines, unless both auxiliary boilers were in use. Whenever it becomes necessary to shut down one of the boilers all machine shop work on the Fulton has to stop. The motor generator requested by the Fulton is one that was a<su>pplied for the Schley and is immediately available. Lieutenant-Commander Minett <Nimitz?>6 in conversation with me was most emphatic in his expression of opinion that the motor generator requested by the Fulton was a necessity. . . .


On October 9th I visited Nahant in company with Captain Lee7 of the Bureau of Steam Engineering. We were shown there the latest development in C-tube work and in the K-tubes. The Nahant Station has a K-tube installed on a tripod off shore from which we were able to hear practically all vessels that passed within sight of the station. The K-tube at present is still in the experimental stage, but is sufficiently far advanced to show that from an acoustic standpoint it is very much superior in range to the C-tube. Personally, I found some difficulty in determining direction of vessels which I could hear, but was assured that beginners usually experience this difficulty and later overcome it very rapidly. At Nahant, as well as at New London, I was impressed with the thoroughness with which the phases of C-tube and K-tube developments were being investigated. Every possible wrinkle seems to be thought of and tested out or at least <listed> for future test. . . .


On October 10th, the French, English and Italian Attaches, Captain Robinson, Captain Lee, several scientists, Lieutenant-Commander Libbey, Lieutenant-Commander McDowell8 and myself went out on the Margaret from Boston in company with two submarines of the “G” class to test the C-tubes and the K-tubes at sea. The weather conditions were unfavorable, and the sea quite rough so that it was deemed inadvisable for the G boats to submerge. The Margaret rolled so heavily that the C-tubes struck against the ship’s side when they were in position for listening. Nothing new was found out regarding the C-tubes on this trip. The submarines, which at no time during the listening experiments were more than two miles away, could be heard, but I experienced difficulty in determining the direction with any degree of accuracy, more experienced observers were correspondingly more successful. The K-tubes were put over and apparently towed very steadily. The Margaret drifted in the trough of the sea broad side to the wind, the K-tube cable tending directly to windward. The submarines could be heard plainly on the K-tube. The experiment cannot be said to have been exhaustive, but sufficiently so to indicate the superior range of the K-tube over the C-tube. . . .

For the information of those who do not know what the K-tube is, I <ap>pen<d> the following description:

A microphone towed at a distance from a vessel has a greater range than the C-tube has. The experimenters at Nahant found that by connecting up two similar microphones this range was still further increased, they then found that by joining the principal of the C-tube to microphones suspended at a depth of 70-feet below the water on a triangular frame work of gas pipe so that the microphones themselves would be 4-feet apart and with the apexes of a triangle 4-feet on each side, they could not only increase the range of a single microphone very much, but they could also determine the direction from which the sound was proceeding. The K-tube as now developed receives the sound in the microphone and transmits it to telephone receivers on board the listening vessel. The telephone receivers are at the receiving ends of a virtual C-tube, which, itself, is subject to the same adjustments as the C-tube pure and simple, so that the direction from which the sound is coming can be determined. The weak link in the K-tube is the assumption that the K-tube itself is towing in the manner it is designed to be towed. Proof of this assumption was not furnished to this board, but assurances were given that previous experience had demonstrated the assumption to be correct.

Source Note: TL, DNA, RG 45, Entry 520. Identification number “Op-17-Mu” appears in the upper-left corner.

Footnote 1: Possibly Lt. Comdr. Edward C.S. Parker.

Footnote 2: A type of mechanical hydrophone lowered from ships to detect submarines. Hydrophones transmitted sound waves under the water and were a forerunner to modern sonar, although their effectiveness in World War I was limited. Still, Crisis at Sea: 327-330; Friedman, Fighting the Great War at Sea: 290-298.

Footnote 3: Possibly Lt. Francis G. Marsh.

Footnote 4: Cmdr. Thomas L. Johnson.

Footnote 5: Lt. Conant Taylor.

Footnote 6: The word “Minett” is crossed out and another name handwritten in that appears to be “Nimitz,” although the handwriting is less-than-perfectly legible. Lt. Cmdr. Chester Nimitz and was one of the navy’s authorities on engines, having designed the new diesel engines for the Maumee. DANFS

Footnote 7: Capt. Richard H. Leigh, Assistant to Bureau of Steam Engineering.

Footnote 8: Cmdr. Bernard A. de Blanpré; Commo. Guy R. Gaunt, R.N.; the identity of the Italian naval attaché is unknown. Lt. Cmdr. Miles A. Libbey and probably Cmdr. Willis McDowell.