202 FRAGMENTS OF SCIENCE. 



The whole of the observations here referred to were em- 

 braced by an angle of about 70 degrees, of which 50 

 degrees lay on the one side and 20 degrees 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 reflector, 

 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 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 degrees 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 through- 

 out. 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 degrees 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 experiments at Shoeburyness that when 

 the broad side of a slab was turned toward 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 

 to the wire this never occurred. To the circumstance that 

 the broadsides of the slabs faced the sea is probably to be 

 ascribed the remarkable fact observed on March 23d, that 

 in two directions, not far removed from the line of fire, the 

 gun-cotton detonated in the open had a slight advantage 

 over the new gun. 



Theoretic considerations rendered it probable that the. 



