Poverof Gunpowder. M. De Saint
Robert, in an article from his pen in
La Berue tsuentifique, gives the follow
ing calculation of the efficiency of a
rined cannon, the diameter of the bore
of which is 3 inches, the shell of which
weighs about 83 lbs., and the firing
charge of which is H lbs. It may thus
be estimated: Experiment has shown
that the velocity of the shell when it
leaves the mouth of the cannon is
about 1.300 fact per second. The
height from which the projectile would
bare to fall to acquire this velocity is
26,800 feet per second. Consequently
the work actually done by the powder
is equal to 219,000 foot pounds. On
the other hand, Bunson and Schisch
koff have found by direct experiment
that the beat evolved by the combus
tion of 23 lbs. of gunpowder is' equal
to 619 5 calories. Hence the ' heat
evolved by the above charge of 1 lbs.
of powder is equal to 340' 7 calories.
