THE HIGHWAY OF THE WATERS 



inside of the hull on each side, with connecting wires 

 leading to the pilot house, in its perfected form will 

 pick up the sound of the submerged bell equally well 

 at any speed, regardless of calm or storm. 



The chief defect of this arrangement was that the 

 sound of the pulsations of the engines of the ship were 

 also heard, and interfered seriously with the detection 

 of the sound of the bell. But presently a receiving de- 

 vice was perfected which ignored all sounds but those 

 of the bell, thus giving the mariner a means of protec- 

 tion against accidents that could be depended upon 

 absolutely at all times regardless of speed or weather 

 conditions. 



When this stage of perfection of the signaling device 

 was reached the various governments began installing 

 the instruments on buoys, lighthouse sites, and light- 

 ships, using various mechanical devices for ringing the 

 bells, and timing the strokes so that the mariners could 

 tell by the intervals just what bell he was in touch with, 

 as he knows each lighthouse by the intervals between 

 the flashes of its lights. A further development in the 

 signaling device was to equip ships with submerged 

 bells, as well as with the receiving apparatus. In this 

 way two ships could communicate with each other, or 

 with a shore receiving station, by using the Morse 

 telegraph code, just as in the case of telegraphy. 



The maximum distance at which such communica- 

 tions may be detected is about fifteen miles, and the 

 approximate distance from the bell can be gauged 

 from the clearness of the sound heard in the tele- 

 phone receiver. At the distance of a quarter of a mile 



[87] 



