the Force of Fired Gunpowder. 159 



sometimes passed through all the screens (five in num- 

 ber) without being broken. 



When they were propelled by large charges, and con- 

 sequently with great velocity, they were seldom on fire 

 when they arrived at the first screen, which was evident, 

 not only from their not setting fire to the paper (which 

 they sometimes did), but also from their being found 

 sticking in a soft board, against which they struck, after 

 having passed through all the five screens ; or leaving 

 visible marks of their having impinged against it, and 

 being broken to pieces and dispersed by the blow. 

 These pieces were often found lying on the ground ; 

 and from their forms and dimensions, as well as from 

 other appearances, it was often quite evident that the 

 little globe of powder had been on fire, and that its 

 diameter had been diminished by the combustion, before 

 the fire was put out, on the globe being projected into 

 the cold atmosphere. The holes made in the screen by 

 the little globe in its passage through them seemed also 

 to indicate that its diameter had been diminished. 



That these globes, or large grains of powder, were 

 always set on fire by the combustion of the charge can 

 hardly be doubted. This certainly happened in many 

 of the experiments, for they arrived at the screens on 

 fire, and set fire to the paper ; and in the experiments 

 in which they were projected with small velocities, they 

 were often seen to pass through the air on fire ; and when 

 this was the case, no vestige of them was to be found. 



They sometimes passed, on fire, through several of 

 the foremost screens without setting them on fire, and 

 set fire to one or more of the hindmost, and then went 

 on and impinged against the board, which was placed at 

 the distance of 12 inches behind the last screen. 



