Deck Guns.—The mounting of deck guns on merchantmen for defence against the submarine has proved of slight value. When it was first proposed to mount guns on American merchant ships I wrote the Navy Department on March 11, 1917, in part as follows: "I have tried, in the interest of this country, to impress this fact upon the people (that the submarine, because it is invisible, is invincible), but I find in talking with many intelligent people, that they do not and cannot comprehend the possibilities of the submarine when it is taken seriously and the effort is made to get all there is out of it, without reference to political, financial, or prejudiced interests. The destructiveness of the submarine is growing; devices which were effective in detecting and trapping submarines early in the war are now becoming useless. The theory that putting a gun on a merchant ship is going to protect that ship, her crew and passengers, will, I fear, be equal to the signing of the death-warrant of all that are on that ship if we are at war, as the slogan in to-day's headlines (as per copy clipping enclosed)—'Sink any ship you see'—will be met, I fear, by a German slogan of 'Sink every ship you meet, but don't let them see you do it.'"

Since that time many ships fully equipped with arms have been sunk by torpedoes and have never seen the submarines which destroyed them. There is no way to attack submarines by gun fire unless they are seen, and commanders of submarines are becoming expert in concealing their presence.

Submarine Guns, Aerial Torpedoes, Searchlights.—For an under-water gun to be effective, there must first be discovered some way to locate the target; this, of course, is almost impossible. Aerial torpedoes or depth bombs might be effective if the submarine were seen, but it is the business of the submarine commander to keep out of sight. Powerful searchlights have very little chance of picking up the periscope or conning tower of a submarine. I remember lying all one night in the Argonaut, during a storm, at the outer edge of the mine fields off Fortress Monroe, at the time the whole country was in dread of an invasion by Cervera's fleet during the Spanish-American War. We were in forbidden territory, having been delayed by the storm in getting into harbor before "Curfew" rang, so to speak. The powerful searchlights of Fortress Monroe were playing all night, but they did not detect our presence, as only our sighting hood was above water, and presented such a small object, and being painted white, it was not distinguished from the "white caps" on top of the sea caused by the storm.

Searchlights under water are useless because of the particles of foreign matter held in suspension which reflect back the glare of the light. The Argonaut was fitted with powerful searchlights and reflectors located in her extreme bow, with a pilot-house or lookout just above the three searchlight windows. The greatest distance we were ever able to see was during some night experiments in the Chesapeake Bay during a long dry spell, when the sediment had had an opportunity to settle, and that was only forty feet. The light would penetrate through the water several hundred feet and make a glow on the surface, but vision could not penetrate the water. For instance, it is said that after a storm a glass of Mississippi River water will show fully an inch of sediment. To see through three or four inches of that kind of water, therefore, one must see through an inch of mud. It is well known that no light has yet been found that will enable vision to penetrate through a heavy fog, due to the reflection of light upon the minute crystals of water held in suspension in the air. It appears hopeless, therefore, to expect vision to locate submarines by seeing through the opaque substance held in suspension in all water.

Echo and Magnetic Devices.—Locating submarines by echo has been proposed, but apparently without thought as to what would happen to the vessel giving out the sound in the effort to get an echo back from a submerged submarine, lying in wait with her "ears" waiting to hear some suspicious sound. Also, magnetic devices for the purpose of detecting submarines, if ever found practical, will probably be kept so busy leading their operators to and investigating large steel ships that have already been sunk by submarines that they will probably miss the little submarine, which can easily sink them while they are investigating these other sunken ships.

Channel and Open-sea Nets.—These have been and are being used with some success, but that success has been attained only because at the beginning of the war the submarines had no means for determining the presence of the nets before becoming entangled in their meshes, and when they once became entangled they had no means to cut themselves loose. Devices are now available which enable the commander of a submarine to locate a net before reaching it, and to destroy that net and all its attached mines with but little danger to his own vessel. To what extent these devices are being used is unknown. However, when the submarine is not especially fitted for the detection and destruction of nets and attached mines, they are probably the most efficient type of trap yet provided for capturing and destroying these "submarine devil fish." The Scientific American published an article by me in 1915 describing a submarine fitted with mine-evading devices and meant to under-run nets, which has been reproduced in the previous chapter.

THE U-65

Photograph copyright by Underwood & Underwood