RECENT EXPERIMENTS ON FOG-SIGNALS 277 



reflector.* The sound produced by the gun-cotton, rein- 

 forced bj the reflector, was unanimously pronounced loud- 

 est of all. With equal unanimity, the gun-cotton deto- 

 nated in free air was placed second in intensity. Though 

 the same charge was used throughout, the guns differed 

 notably among themselves, but none of them came up to 

 the gun-cotton, either with or without the reflector. A 

 second series, observed from a different distance on the 

 same day, confirmed to the letter the foregoing result. 



As a practical point, however, the comparative cost of 

 gun-cotton and gunpowder has to be taken into account, 

 though considerations of cost ought not to be stretched 

 too far in cases involving the safety of human life. In 

 the earlier experiments, where quantities of equal price 

 were pitted against each other, the results were somewhat 

 fluctuating. Indeed, the perfect manipulation of the gun- 

 cotton required some preliminary discipline — ^promptness, 

 certainty, and effectiveness of firing, augmenting as expe- 

 rience increased. As 1 lb. of gun-cotton costs as much as 

 8 lbs. of gunpowder, these quantities were compared to- 

 gether on the 22d of February. The guns employed to 

 discharge the gunpowder were a 12-lb. brass howitzer, a 

 24-lb. cast-iron howitzer, and the long 18-pounder em- 

 ployed at the South Foreland. The result was, that the 

 24-lb. howitzer, firing 3 lbs. of gunpowder, had a slight 

 advantage over 1 lb. of gun-cotton detonated in the open; 

 while the 12-lb. howitzer and the 18-pounder were both 

 beaten by the gun-cotton. On the 2d of May, on the other 

 hand, the gun-cotton is reported as having been beaten 

 by all the guns. 



* For charges of this weight the reflector is of moderate size, and may be 

 employed without fear of fracture. 



