712 



Pojmlar Science Monthly 



V^ 



Mr. Berger's device resem- 

 bles in principle the tomato- 

 can toy. On the other hand, 

 sounds sent out into the water 



.JjtUi^ 



The signals sent out undLr the water are 

 picked up by a microphone in the vessel 



device. Is it not enough that men can 

 signal through air with whistles and 

 lights, through ether with wireless 

 telegraphy, and over wires with the 

 aid of electricity? 



The answer is this: Strong as men 

 have built ships, as well as they have 

 chartered the ocean, as many safety 

 devices as they have installed on boats, 

 one overpowering danger still confronts 

 navigators. That danger is fog. In a 

 thick fog it is almost impossible to see 

 from one end of a boat to the other, let 

 alone out over the water toward any 

 approaching vessels. Sound-signals do 

 not carry far in air and are most un- 

 trustworthy. Hcnco the freriucnt mis- 

 haps which occur when bell-buoys, or 

 other sound warnings near hidden reefs 

 are not heard. Signal lights, rockets, 

 lanterns, and similar de\'ict's depending 

 upon light ari' obxiously inopcrati\e in a 

 fog. Wireless waves — usually so cfTecl- 

 ive in warnings of sea flangers — li.ne 

 their limitations, too. Unless the op- 



erators carry on specific conversation as 

 to their ships' positions and the danger of 

 biniiping into each other or into objects 

 on shore, the wireless signals them- 

 selves carry no warning of impending 

 disasters; the strength of wireless sig- 

 nals, as received, is no criterion of the 

 sending ve-ssel's distance. 



Hence when a fog descends over the 

 sea, light signals are utterly useless, 

 sound signals in air do not carry far and 

 are uncertain, and wireless telegraphy is 

 good onl\- in certain instances. Is it any 

 wonder that inxenlors have taken to 

 iiixestigating the possibilities of sub- 

 marine signaling, all the more since they 

 have discovered that sountl -signals will 

 carr\- long distances under water and are 

 unalTected by fogs and storms? 



