The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

32 THE Marine REVIEW yow-have such good success. This is highly proper and is as it should be. In conclusion I wish to say that it is simply impossible for one to explain himself on the subject under discus- sion in so limited a space. I find it. difficult to write on so many subjects without going into detail. All these subjects will be brought out in detail before the lessons are completed. If.you do not thoroughly understand all that I have said and you desire more information let us hear from you as many times as you like. This is what this department is for. I wish to thank you especially since you are the first to start the "ball rolling" in the right direction. You are not afraid to say what you think, and this is commendable in you. LONG. SUBMARINE SIGNALING. Mr. J. B. Millet, the president of the Submarine Signal Co., of Boston, delivered an exceedingly interesting lecture on "Submarine Signaling by Means of Sound," in London, on May 2. In the course of his address Mr. Millet traced the history of his company from its birth in 1895, this inter- esting event happening in consequence of Mr. A. J. 'Mun- daz, one of the chief inventors, trying to devise means of utilizing a telephone receiver for hearing the sounds pro- duced under water. After describing a number of experi- ments made on the New England coast the lecturer said that eventually the old frigate Constitution, with its 22-inch oaken walls, proved to be an excellent conductor of sub- marine sounds. In order to carry on extended observa- tions, arrangements were made for the use of four steamers of 3,000 tons each, plying between Boston and New York, and permission was obtained from the United States light- house department to place submarine bells on three light- ships on the route. From this time the operations of the company were conducted along lines which led them to success on a practical basis. The existing sound-producing apparatus used by the com- pany is as follows:--First, a bell weighing 160 lbs. operated by compressed air and perfected for use on lightships. This is suspended over the side of the vessel and lowered about 25 ft. below. the surface. The blows are controlled by a code-ringing device in the engine-room, wunder the super- vision of the officers, so that each lightship rings its own . number. Second, a bell of similar weight, supported on a~ tripod placed on the floor of the ocean and operated by electricity sent along a cable from a power-house on shore. Third, a buoy supporting a submarine bell of Lke weight, © some 25 feet below the surface. Situated above the bell is a disc working on the principle of a sea anchor; the dif- ference in movement between this and the buoy' operates a mechanism known as the "accumulator," by which the bell is struck with uniform force. On a calm sea the blows will, of necessity, be less frequent than when the waves are larger, but a wave of only 6 in. in height will give suf- fic'ent energy to produce two blows per minute. The tones of these bells have a range varying from six to twelve miles, according to the draught of the observing steamers. The pitch of the bells can be varied by altering the thickness of the rim, or by increasing the diameter. Those used in the earliest experiments weighed 1,000 pounds, and were cast for church steeples. Practice showed that the higher overtones of these bells were weak, while those very notes possessed the most penetrating qualities. In order to strengthen these tones, bells less than one-half the diameter, and weighing only 150 lbs. were cast, with a peculiarly thick lip, and these were found to produce a very high clear note. This diminution in the size, and de- crease in the weight of the bell, greatly simplified the prob- lem of designing a practical bell buoy, It was even found that a bell 4 in. in. diameter gave a high tenor note that penetrated the walls of the steamer at a distance of three miles. One of the puzzling results of experiments was that instruments which gave a poor musical tone in the air often proved singularly efficient in water. The apparatus for receiving the sound consists, firstly of two metal tanks about 22 in. square, filled with sea water, fastened securely against the skin of the ship below the water line, and not less than a demonstrated distance from the fore foot. Secondly, a specially designed micro- phone suspended, wholly immersed, in each tank. Thirdly, wires connecting these microphones with an indicator box on the bridge. This box is of metal, circular in shape and is fitted with two telephonic ear pieces, or receivers, en- abling two observers to listen simultaneously. By moving a switch the listener can hear instantly the .sounds of port or starboard at will. As a provision against accident, a second set of microphones is placed in each tank, and by manipulating another switch on the indicator box, the operator is able to connect either set. The method of using the apparatus is remarkably simple. Let it be supposed that a ship equipped as above is coming within range of the' sound of a submarine bell. The ob- server, with the receiver to his ear, listens to starboard and port alternately by quickly turning the requisite switch. Presently he hears the unmistakable, high, musical note of the bell, and referring to the face of the indicator, can tell from which side the sound emanates. He' then connects with the other side, and if the note of the bell can be dis- tinguished there also, the observer knows that the ship is heading in the general direction of the signal. It then becomes his duty to compare, by turning the switch to and fro, the intensity of the bell notes on starboard and port sides. Experience, has shown that by this method the bearing of the submarine bell can be rapidly determined to within less than a quarter of a point. Of course, if the bell is abeam or nearly so, the sound will only be heard on that side. These observations can be made when the ves- sel is proceeding at its full speed, and, under such condi- tions, signals have been often accurately located at distances up to ten nautical miles. In foggy or thick weather, when -speed is reduced, the diminution in the ship's noises enables the observer to hear the bell at greater distances. These results are valuable, not only on account of the long range of the signal, but because the direction can be accurately determined under all weather corditions, whereas it js notorious that sound-signals in the air are wholly untrust- worthy. A remarkable illustration of this fact recently: came under my notice. A party of observers set out to test the sound-range of a siren on 4 lightship. The con- ditions were favorable--a calm sea and a clear, still air. The boat approached nearer and nearer the lightship, but not a sound reached the cargo of listening experts. At a distance of 600 yards, without the slightest warning, these gentlemen were all deafened by an apparently sudden roar from the siren, which continued until they boarded the lightship. Inquiry amply proved that the instrument had been sounding at its full pitch, continuously for over three hours. I do not suggest, however, that sound-signals in the air should be superceded. This invention is intended as an aid to navigation. After quoting testimonials received from the captains of vessels belonging to the Cunard line, the Norddeutscher Lloyd line, and the officers of the U. S. navy ships, Mr. Millet said that it is, however, to the lighthouse establish- ment of the United States and to the Department of Ma- tine and Fisheries of Canada that our company is most deeply indebted. Such success, and such honor attaching thereto, as has attended the work of the Signal company