264 FRAGMENTS OF SCIENCE. 



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 13| miles from the firing-point. In 

 all these observations, the reinforcing action of the re- 

 flector, and of the parabolic muzzle of the gun, came 

 into play. But the reinforcement of the sound in one 

 direction implies its withdrawal from some other di- 

 rection, and accordingly it was found that at a distance 

 of 5 miles from the firing-point, and on a line includ- 

 ing nearly an angle of 90 with the line of fire, the 

 gun-cotton in the open beat the new gun; while be- 

 hind 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 upwards or downwards, 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 sides of the bell, 

 and not its mouth, emitted the strongest sound, their 

 practice being probably determined by this knowledge. 

 Our slabs of gun-cotton also emit waves of different 

 densities in different parts. It has occurred in the ex- 

 periments at Shoeburyness that when the broad side 

 of a slab was turned towards the suspending wire of a 

 second slab six feet distant, the wire was cut by the 

 explosion, while when the edge of the slab was turned 



