the Force of Fired Gimpowder. 1 1 9 



immediately, and even the flat surface of the hemisphere, 

 notwithstanding it was of hardened steel and very highly 

 polished, was sensibly corroded. This corrosion of the 

 mouth of the bore, by which the dimensions of the sur- 

 face upon which the generated elastic fluid -acted were 

 rendered very uncertain, would alone have been sufficient 

 to have rendered all my attempts to determine the force 

 of fired gunpowder abortive, had I not found means to 

 remedy the evil. The method I employed for this pur- 

 pose was as follows. Having provided some pieces of 

 very good compact sole-leather, I caused them to be 

 beaten upon an anvil with a heavy hammer to render 

 them still more compact ; and then, by means of a 

 machine made for that purpose, cylindric stoppers, of 

 the same diameter precisely as the bore of the barrel, 

 and 0.13 of an inch in length (that is to say, equal in 

 length to the thickness of the leather), were formed of 

 it ; and one of these stoppers, which had previously 

 been greased with tallow, being put into the mouth of 

 the piece after the powder had been introduced, and 

 being forced into the bore till its upper end coincided 

 with the end of the barrel, upon the explosion talcing 

 place, this stopper (being pressed on the one side by 

 the generated elastic fluid, and on the other by the 

 hemisphere, loaded with the whole weight employed to 

 confine the powder) so completely closed the bore that 

 when the force of the powder was not sufficient to raise 

 the weight to such a height that the stopper was actually 

 blown out of the piece, not a particle of the elastic fluid 

 could make its escape. And in those cases in which the 

 weight was actually raised, and the generated elastic fluid 

 made its escape, as it did not corrode the barrel in any 

 other part but just at the 'very extremity of the bore, the 



