262 FRAGMENTS OF SCIENCE. 



equal unanimity, the gun-cotton detonated 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 jexperiments, where quantities of 

 equal price were pitted against each other, the results 

 were somewhat fluctuating. Indeed, the perfect ma- 

 nipulation of the gun-cotton required some prelimi- 

 nary discipline promptness, certainty, and effective- 

 ness of firing, augmenting as experience increased. 

 As 1 Ib. of gun-cotton costs as much as 3 Ibs. of gun- 

 powder, these quantities were compared together on 

 the 22nd of February. The guns employed to dis- 

 charge 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 Ibs. of gunpowder, had a 

 slight advantage over 1 Ib. 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 2nd of 

 May, on the other hand, the gun-cotton is reported as 

 having been beaten by all the guns. 



Meanwhile, the parabolic-muzzle gun, expressly in- 

 tended for fog-signalling, was pushed rapidly forward, 

 and on March 22 and 23, 1876, its power was tested at 

 Shoeburyness. Pitted against it were a 16-pounder, a 

 5-ineh howitzer, 1^ Ib. of gun-cotton detonated in the 

 focus of a reflector (see annexed figure), and 1| Ib. of 



