RECENT EXPERIMENTS ON FOG-SIGNALS 279 



cotton clearly dominated over all the other sound-pro- 

 ducers.* 



The whole of the observations here referred to were 

 embraced by an angle of about 70°, of which 50° lay oa 

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

 The shots were heard by eleven observers on board the 

 "Galatea," which took up positions varying from 2 miles 

 to 133^ 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 5^ 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 83^ miles and ISJ^ 

 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 13J^ 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 



' The reflector was fractured bj the explosion, but it did good servioe 

 afterward. 



