112 RECENT DEVELOPMENTS IN SUBMARINE SIGNALING. 



been invented. All of them depend either upon the transmission of sound in the 

 air or upon observations in temperature, and none are trustworthy. Experiments 

 made by Professor Fessenden in the North Atlantic on board the United States 

 revenue cutter Miami, have proven quite conclusively, however, that the presence 

 of icebergs may be detected by operating an oscillator on board ship in such a way 

 as to send out a powerful sound wave under water, and then observing the time 

 and direction from which echoes are returned. An authoritative account of this 

 experiment is given by Captain Quinan as follows : 



"We stopped near the largest berg, and by range-finder and sextant computed 

 it to be 450 feet long and 130 feet high. Although we had gotten within 150 yards 

 of the perpendicular face of this berg and obtained no echo from the steam whistle, 

 Professor Fessenden and Mr. Blake, representatives of the Submarine Signal Com- 

 pany, obtained satisfactory results with the submarine electric oscillator placed ten 

 feet below the surface, getting distinct echoes from the berg at various distances, 

 from one-half mile to two and one-half miles. These echoes were not only heard 

 through the receivers of the oscillator in the wireless room, but were plainly heard 

 by the officers in the wardroom and engine-room storeroom below the waterline. 

 Sound is said to travel at the rate of 4,400 feet per second in water. The distance 

 of the ship, as shown by the echoes with stop-watch, correspond with the distance 

 of the ship as determined by range-finder." 



It may be noticed that any ship which is equipped with the oscillator for ordi- 

 nary purposes of navigation is at the same time provided with all that is neces- 

 sary to obtain the same results in detecting the presence of icebergs that Professor 

 Fessenden and Mr. Blake secured. 



The value of the submarine in war is now being tried out practically for the 

 first time. The British and the German navies are both thoroughly equipped with 

 this arm. Whether Sir Percy Scott is right in giving the submarines a greater im- 

 portance as a fighting arm than the dreadnoughts may be determined in the next 

 few months. Whether it is or not, there is no question whatever that the recent 

 improvements in submarine signaling will make the submarine a much more effi- 

 cient instrument in warfare. 



The receiving apparatus now in common use consists, as has been stated, 

 of a granular transmitter which hears everything that comes to it, whether it be a 

 noise on board ship or a jar of any kind which disturbs the granules in the trans- 

 mitter, or a noise coming through the water. Professor Fessenden's oscillator, 

 however, when used as a receiving instrument, hears nothing of the noises on board 

 ship, consequently we may imagine a submarine boat fitted out with two ears, one 

 on each side well forward with which to pick up any sounds that may come to it 

 through the water, and which will not be disturbed by any of the noises made in- 

 side the craft. Thus provided, a submarine boat could stalk a battleship or a de- 

 stro5^er by listening to the noises which come to it. In fact this may be done now by 



