I 
2 6 8 Mr. Thompson’s Experiments 
of the piece ; but as the bullet gives way to the p reflu re, and 
moves on in the bore, the fluid will expand itfelf and grow 
weaker, and the particles of the metal will gradually return 
to their former fituations ; but the velocity with which the 
metal reftores itfelf being but fmall, the vibration that remains 
in the metal, after the elaftic fluid has made its efcape, will be 
very languid, as will be the heat that is generated by it. 
But if, infiead of giving way with fo much difficulty, the 
bullet is much lighter, fo as to afford but little refiftance to the 
elaftic fluid in making its efcape, or if the powder is fired with- 
out any bullet at all ; then, there being little or nothing loop- 
pole the flame in its paflage through the bore, it will expand 
itfelf with an amazing velocity, and its adtion upon the gun 
will ceafe almoft in an inftant, the ffrained metal will refiore 
itfelf with a very rapid motion, and a ffiarp vibration will 
enfue, by which the piece will be much heated. 
Of the effeft of ramming the powder in the chamber of the piece. 
The charge, confifting of 2 1 8 grains of powder, being put 
gently into the bore of the piece in a cartridge of very fine 
paper, without being rammed, the velocity of the bullets at a 
mean of the 40th, 4.1ft, 42 d, and 47th experiments, was 
at the rate of 1225 feet in a fecond; but in the 68th, 69th, 
and 70th experiments, when the fame quantity of powder was 
rammed down with five or fix hard ftrokes of the ram-rod, the 
mean velocity was 1329 feet in a fecond. Now the total force 
or prefllire exerted by the charge upon the bullet is as the fquare 
of its velocity, and 1329” is to 1225' as 1,1776 is to 1 ; or 
nearly 
