RECENT EXPERIMENTS ON FOG-SIGNALS 279 



eotton clearly dominated over all the other sound-pro- 

 ducers. l 



The whole of the observations here referred to were 

 embraced by an angle of about 70, of which 50 lay on 

 the one side and 20 on the other side of the line of fire. 

 The shots were heard by eleven observers on board the 

 44 Galatea,'* which took up positions varying from 2 miles 

 to 13% miles from the firing-point. In all these observa- 

 tions, the reinforcing action of the reflector, and of the 

 parabolic muzzle of the gun, came into play. But the re- 

 inforcement of the sound in one direction implies its with- 

 drawal from some other direction, and accordingly it was 

 found that at a distance of 5J miles from the firing-point, 

 and on a line including nearly an angle of 90 with the 

 line of fire, the gun-cotton in the open beat the new gun; 

 while behind the station, at distances of 8% miles and 13% 

 miles respectively, the gun-cotton in the open beat both, 

 the gun and the gun-cotton in the reflector. This result 

 is rendered more important by the fact that the sound 

 reached the Mucking Light, a distance of 13% miles, 

 against a light wind which was blowing at the time. 



Most, if not all, of our ordinary sound-producers send 

 forth waves which are not of uniform intensity throughout. 

 A trumpet is loudest in the direction of its axis. The 

 same is true of a gun. A bell, with its mouth pointed 

 upward or downward, sends forth waves which are far 

 denser in the horizontal plane passing through the bell 

 than at an angular distance of 90 from that plane. The 

 oldest bellhangers must have been aware of the fact that 



1 The reflector was fractured by the explosion, but it did good service 

 afterward. 



