TRACT 34.

IN GUNNERY, 1791.

149

Gun

Weight

Bore’s

length

diameter

Long

Medium

Light

lbs

1370

1173

633

inches

80-5

56-65

56.6

inches

3-65

3-65

3-65

These weights were those of the guns alone, without theiron apparatus for suspending them, when they were used inthat way, which was the same for ali the guns, and weighed248lb.—The bore of the guns terminated at the bottom inthe form of a hemisphere: and the charge of powder wasput into very thin paper bags, shaped round at the bottom,so as to fit very nicely the end of the bore. The guns weresometimes suspended like pendulums, vibrating very treely,and at other times placed upon sliding carriages, to checkthe gun’s recoil, thus reducing it to a very small quantity,to try if it would make any difference in the velocity withwhich the balls might be projected.—The weight of the ballswas usually 6lb lf-oz, and their diameter 3 - 55.

The states of the barometer and thermometer were taken,to judge of the effects of the weather on the powder, and onthe resistance of the air against the balls.—The powder wasproved everyday by my new eprouvette, which shows veryminute differences in the strength of the powder, and ena-bled us to regulate its strength, by keeping it always to thesame degree. And indeed it proved very fortunate that wehad such an eprouvette to employ, as it served to detect achange that had been made in the powder, which we shouldnot otherwise have been aware of. For, the powder thathad been used the year before gave only from 35 to 36 vi-bration of the eprouvette; whereas that which we beganwith this year gave from 42 to 43, constantly; and we expected that all the remaining barrels were of the same kind ;but this did not turn out to be the case; for, after someday’s experiments, on entering upon another barrel, wewere surprised to find that the eprouvette showed it to be