268 Mr. Thompson’s Experiments 
of the piece ; but as the bullet gives way to the preffure, 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 frnall, 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, inftead 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 wich- 
out any . bullet at . all ; then, there being little or nothing toop- 
pofe .the flame in its paflage through the bore, it will expand 
itfelf with an amazing velocity, and its action upon the gun 
will ceafe alrnoft in an inftant, the {trained metal will reftore 
itfelf with a very rapid motion, and a fbarp vibration will 
enfue, by which the piece will be much heated. 
Of the ejf'etl of ramming the powder in the chamber of the piece . 
The charge, confiftlng of 218 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, 41ft, 43d, and 47th experiments, was j 
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 preffure 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 
