Experhnents upon GtLnpowder. 67 



their velocities can only be ascertained at some distance 

 from the gun, and after they have lost a part of their 

 initial velocities by the resistance of the air through 

 which they are obliged to pass to arrive at the pendu- 

 lum. 



At the trifling expence of ten or fifteen pounds, an 

 apparatus might be constructed that would answer for 

 making the experiments with all the different kinds of 

 ordnance in the British service. The advantages that 

 might be derived from such a set of experiments are too 

 obvious to require being mentioned. 



Of a very accurate Method of proving Gunpowder. 



All the eprouvettes^ or powder-triers, in common use 

 are defective in many respects. Neither the absolute 

 force of gunpowder can be determined by means of 

 them, nor the comparative force of different kinds of 

 it, but under circumstances very different from those in 

 which the powder is made use of in service. 



As the force of powder arises from the action of an 

 elastic fluid that is generated from it in its inflamma- 

 tion, the quicker the charge takes fire, the more of this 

 fluid will be generated in any given short space of time, 

 and the greater of course will be its effect upon the bul- 

 let. But in the common method of proving gunpow- 

 der, the weight by which the powder is confined is so 

 great in proportion to the quantity of the charge, that 

 there is time quite sufficient for the charge to be all 

 inflamed, even when the powder is of the slowest com- 

 position, before the body to be put in motion can be 

 sensibly removed from its place. The experiment, there- 

 fore, may shew which of two kinds of powder is the 

 strongest when equal quantities of both are confined in 



