the Force of fired Qunpowder. 243 
bore, by which the dimensions of the surface upon which the 
generated elastic fluid acted were rendered very uncertain, 
would alone have been sufficient to have rendered all my at- 
tempts to determine the force of fired gunpowder abortive, had 
l not found means to remedy the evil. The method I pursued 
for this purpose 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 pur- 
pose, 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, the thickness of the leather), were formed of it; and one 
of these stoppers, which had previously been greased with tal- 
low, 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 ex- 
plosion taking place, this stopper (being pressed on the one 
side by the generated elastic fluid, and on the other by the he- 
misphere, 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 extre- 
mity of the bore , the experiment by which the weight was as- 
certained, which was just able to counterbalance the pressure 
of the generated elastic fluid, was in nowise vitiated, either by 
the increased diameter of the bore at its extremity, or by any 
MDCCXCVII. K k 
