Signalling and Safety at Sea. 15 



with the carriage of the bell-sound ; the light flashes being 

 probably of lesser range and for the use of smaller vessels 

 which can generally approach with safety nearer to the coast 

 owing to shallow draught. The emission of wireless signals 

 at intervals of one or two minutes would be quite adequate, 

 and economy of current would be attained. 



The Fessenden Oscillator has long been a potential rival 

 io the submarine bell as a means of generating sound waves 

 in water. But lately such developments of the Oscillator 

 have been made that it seems highly probable that on the 

 more important ships it will take the place of the bell. 

 Professor Fessenden has, in short, by his recent improvements 

 rendered possible uses of submarine signalling almost 

 unhoped for, although often wished for in the past. On the 

 results of the experiments claim has been made to — 



(a) Increased radius of audibility up to 30 miles or even 



more. 



(b) The easy signalling by Morse code over these great 



distances by an ordinary telegraph key. 



(c) The receipt and emission of the signals by one and 



the same apparatus located in the ship or lowered 

 overboard. 



To these may be added the following, provisionally on 

 further experiments proving as successful as those already 

 -made : — 



(d) The determination of depth beneath the moving vessel 

 by echo from the bottom. 



(V) The location of icebergs by reflected sound from the 

 submerged part of the berg. 



The transmission of speech over short but useful distances 

 is, in addition to the claims founded on experiments, a 

 highly probable development. What these claims involve 

 may not at first be fully realized. Even if we accept the 

 first three only we approach the consideration of the instru- 

 ment on which these are founded with considerable interest. 



The new Oscillator is not in principle different from the 

 earlier invention of Professor Fessenden. The sound 

 generated in the water originates in the rapid in-and-out 

 vibration of a metallic diaphragm. This diaphragm may 

 form part of the side of the ship. Now, obviously, the 

 difficulty to be overcome in making such an apparatus 

 successful is to generate and apply a force of sufficient 

 intensity to overcome the inertia of the diaphragm and other 

 moving parts (weighing in point of fact over 100 lb.) as 

 well as that of the water, in a space of time measured in 



