98 



PRESIDENT S ADDRES SECTION B. 



upon whicli improvements in modern gunpowder are based lies in 

 the slowing down of the powder, and this alteration became neces- 

 sary by the introduction of rifled ordnance. It is now required 

 that when the charge is fired in the breach of the gun the com- 

 bustion shall commence comparatively slowly, so as to overcome 

 the vis mertice of the projectile, and that as the projectile passes up 

 the bore of the gun the combustion shall increase in rapidity, so as 

 to supply a progressively increasing quantity of gas to accelerate 

 the momentum of the shot, Avhich should leave the muzzle of the 

 gun with the maximum velocity. The Service powder known 

 as E.L.G. represents the first attempt in this direction, and this 

 improvement was accomplished by incx'easing the size and shape 

 of the grains. A further improvement was made by increasing 

 the density of the powder, as in P2 powder, and it was found on 

 experiment that a charge of P2 powder equal to that of R.L.G. 

 gave considerably reduced pressure in the gun, accompanied by 

 ■an increased muzzle velocity of the projectile ; but, as even these 

 powders exerted too great a strain upon the gun, it became neces- 

 sary to slow down still more, and many suggestions were made 

 with this object in view. General Rodman, of the American 

 Service, first overcame this difficulty with some sviccess by build- 

 ing up a charge of solid slabs perforated Avith holes, the object 

 being to expose a minimum surface of powder at the commence- 

 ment of combustion, and an increasing surface as the projectile 

 moved up the bore of the gun. 



Fig. 1. 



Fig. 2. 



It Avas in accordance with this idea that the Black Prism powder 

 was first made, and it needs no explanation to demonstrate that a 

 charge of powder moulded to a regular shape, and of uniform size, 

 must give more uniform results (ceteris paribus) than can be 

 obtained by an equal weight of irregular grains or lumps. This 

 modern-shaped powder, however, possesses other advantages of 

 considerable import over the irregular P2 powder, which burns 

 from surface to centre, and thus has a continually decreasing sur- 

 face of combustion as the shot travels up the bore of the gun. The 



