RECENT DEVELOPMENTS IN SUBMARINE SIGNALING. Ill 



the "oscillator." This appears to be the last word on submarine signaling, and it 

 it is of immense importance, for it opens the door to a field which is filled with 

 extremely important possibilities. Without going into a detailed description of 

 the oscillator, it is necessary to say that it consists of a very large and heavy dia- 

 phragm vibrated under water by an electric mechanism with sufficient force and 

 frequency to generate waves of sound of tremendous power. As these vibrations 

 may be stopped and started at any time by the pressing of a button, it becomes evi- 

 dent that the Morse alphabet may be used for the purpose of sending signals. The 

 device which the submarine signal company has used in their demonstrations is a 

 very large and heavy apparatus weighing eight hundred and fifty pounds. In or- 

 dinary experiments it is suspended in the water, but when installed for use on board 

 ship it would be supported against the inside wall of the ship or form a part of it. 

 During tests in Boston Harbor it was found that the oscillator telegraphic signals 

 could be distinctly heard through the water for a little over thirty miles, which of 

 course is far in excess of any distance recorded for the transmission of bell sounds. 

 A more important point, however, to be realized is that this is by no means the limit 

 of distance. Unquestionably oscillators could be built which would transmit a sound 

 much farther than that. We may imagine, therefore, that if steamships traversing 

 the seas are provided with oscillators which can send out under-water signals as 

 warnings to vessels from twenty-five to thirty miles away, navigation in fog would 

 lose its terrors. The oscillator was thus intended to provide the much needed sound 

 producer, but it has been found that it is a very efficient sound receiver as well. In 

 other words, the apparatus which creates sound under water may be used to re- 

 ceive sounds. It has, in fact, certain distinct advantages over the ordinary tele- 

 phonic receiver such as is now being used on ships, which are as follows: The 

 granular transmitter, when shaken or agitated in any way (as by the jar of a 

 ship's machinery), transmits disturbing sounds. Anyone who uses the telephone 

 has noticed such foreign sounds. These sounds when transmitted on board ship 

 are classed as "ships' noises." They frequently interfere seriously with hearing 

 sound signals coming through the water, and one of the great problems that this 

 invention has tried to solve has been to "cut out ships' noises" in order to give the 

 sound signals in the water the best opportunity to be heard; consequently it has 

 sometimes happened that ships have been obliged to slow down or even to stop in 

 order to get under-water signals at long distances. Professor Fessenden's oscilla- 

 tor, however, when used as a receiver, by reason of its construction, can not pick 

 up any sounds which originate within itself, and it does not hear any of the sounds 

 which come to it through the air or through the ship's hull, consequently it should 

 be, when carried to its limits of sensitiveness, a more efficient apparatus for receiv- 

 ing submarine signals than the granular transmitter which is now in common use. 



It is safe to say, therefore, that this invention provides navigators with the one 

 apparatus needed to complete the system when used for the avoiding of collisions 

 between ships at sea. 



Various kinds of apparatus for detecting the presence of icebergs at sea have 



