225 
the Force of fired Gunpowder. 
ends, by two long screws, like the breech-pin of a musket; 
each of which entered 2 inches into the bore, leaving only a 
vacuity of 1 inch in length for the charge. The powder was 
introduced into this cavity by taking out one of the screws, or 
breech-pins; which being afterwards screwed into its place 
again, and both ends of the barrel closed up, fire was com- 
municated to the powder by a very narrow vent, made in the 
axis of one of the breech-pins for that purpose. The chamber, 
which was 1 inch in length, and \ of an inch in diameter, be- 
ing about half filled with powder, I expected that when the 
powder should be fired, the generated elastic fluid being obliged 
to issue out at so small an opening as the vent, which was no 
more than ~ of an inch in diameter, instead of giving a smart 
report, would come out with something like a hissing noise ; 
and I intended, in a future experiment, to confine the gene- 
rated elastic fluid entirely, by adding a valve to the vent, as I 
had done in some of my experiments mentioned in my paper 
published in the LXXI. Volume of the Philosophical Transac- 
tions. But when I set fire to the charge (which I took the 
precaution to do by means of a train), instead of a hissing 
noise, I was surprised by a very sharp and a very loud report ; 
and, upon examining the barrel, I found the vent augmented 
to at least four times its former dimensions, and both the screws 
loosened. 
Finding, by the result of this experiment, that I had to do 
with an agent much more troublesome to manage than I had 
imagined, I redoubled my precautions. As the barrel was not 
essentially injured, its ends were now closed up by two new 
screws, which were firmly fixed in their places by solder, and 
a new vent was opened in the barrel itself. As both ends of 
