252 Count Rumford’s Experiments to determine 
more curious than an experiment of this kind would be, if it 
were successful. 
But to proceed to the experiments by which I endeavoured 
to ascertain the force of fired gunpowder. All the parts of the 
apparatus being ready, it was in the autumn of the year 1792 
that the first experiment was made. 
The barrel being charged with 10 grains of powder (its con- 
tents when quite full amounting to about 28 grains), and the 
end of the barrel being covered by a circular piece of oiled 
leather, and the flat side of the hemisphere being laid down 
upon this leather, and a heavy cannon, a twenty-four pounder, 
weighing 8081 lbs. avoirdupois, being placed upon its cascabel 
in a vertical position upon this hemisphere, in order to confine 
by its weight the generated elastic fluid, the heated iron ball 
was applied to the end of the vent tube; and I had waited but 
a very few moments in anxious expectation of the event, when 
I had the satisfaction of observing that the experiment had 
succeeded. The report of the explosion was extremely feeble, 
and so little resembling the usual report of the explosion of 
gunpowder, that the by-standers could not be persuaded that 
it was any thing more than a cracking of the barrel, occasioned 
merely by its being heated by the red-hot ball : yet, as I had 
been taught by the result of former experiments not to expect 
any other report, and as I found upon putting my hand upon 
the barrel that it began to be sensibly warm, I was soon con- 
vinced that the powder must have taken fire ; and after wait- 
ing four or five minutes, upon causing the weight which rested 
upon the hemisphere to be raised, the confined elastic vapour 
rushed out of the barrel. Upon removing the barrel and exa- 
mining it, its bore was found to be choaked up by the solid 
