fired gun-powdel 79

D = io feet, and consequently C = 22 * then substitu-ting these values in the expression of the velocity,C D

-- — u\ if the value of m be the fraction of a foot, the

tm

velocity « w ill be expressed in feet. For instance, if m befound experimentally =5 of a foot, then 1571 feet will bethe value of u.

166. This machine was used in making the following ex-periments which lead to the solution of several very impor-tant problems in the theory and practice of artillery.

1. The first gun was 5 ft. 6 in. in length of bore,and the weight of leaden bullets was 2s oz.

2. The second was 5 ft. 10 in. in length of bore,and the weight of bullet gx oz.

3. A rifled barrel 3 ft. 5 in. in length of bore, and theweight of bullet f oz.

4. Several mufquet barrels of different lengths; theleaden bullets weighing 1 oz.

The powders were those described in the fortieth paragraph,the wads were of parchment torn in several places, that theymight not damage the rim of paper fastened round the cir-cumference of the wheel; and lightly compressed by the fameman. During these experiments particular attention was paidto moisture of the atmosphere, as its variations sensibly affectthe force of powder (137).

167. The following is a table of initial velocities deducedfrom experiments with a mufquet 3 ft. 6 in. in length of bore,under three different states of the atmosphere.

Velocity Observed.

The charge of

Very moist

Under a mean Very dry

Powder was

Weather.

state of the at-

Weather.

7 drams.

Feet.

mosphere.

Feet.

Feet*

Common War Powder 1902

— 1542

— 1618

Fine Ditto

1569

— 1736

—- 1829

Fowling Ditto

— 1566

— 1703

— *784

Fire-work Ditto

—- 1566

— 1706

— 1774

Beside