I

r

i

FIRED GUN-POWDER. YL

mined by experiment, the elasticity = n of the fluid maybefound by the means of the theorem 9962 — mq ; and by

substituting

Jgb .^nplA

in the theorem V = \r ——-the values

of r, — E B, A = the height of a barometer made of thefame metal as the shot, and p the ratio between the trapeziumE M N B and the rectangle EMxEB, the value of theinitial velocity = V of the shot will be likewise found.

Fig. 21. For example, suppose D A p to be a wall-piece, whose thicknesses of metal are in equilibrio with agiven charge; let the diameter DP = 2r=2 inches,E F the greatest thickness of metal in the place wherethe shot is lodged =m —2 inches, and the tenacity ofmetal=4723200 = ?; by substituting these data in the

theorem 9962 nr=m q, n 9962 x ^ x 4723200: the

greatest elasticity of the fluid = n is therefore nearly equalto 800 times the mean pressure of the atmosphere.

To find the initial velocity of a leaden bullet fired fromthis wall-piece let E B — /— 3^ feet, and p — y-, A will beabout 3 feet; then substituting these values in the theoremV —

y/S

.54»^/A_

it will give V —

96.54 x 800 x _ x 2I x 3

2 f -g

— j8oo for the initial velocity of the leaden bullet.

But if an iron shot be fired from it, A will be equal to 4!feet, and the initial velocity will be

V =

96.54.x 800X-X4ZX z

-;- 2 - = 2043 .

CHAP.

4