212

THEORY AND PRACTICE

TRACT 37.

5. An ample account is given of these experiments, andthe results deduced from them in the 34th Tract; some fewcircumstances only of which may be repeated here. In thiscourse, four brass guns were employed, very nicely boredand cast on purpose, of different lengths, but equal in allother respects, viz, in weight and bore, &c. The lengths ofthe bores of the guns were,

the gun n° i, was 15 calibres, length of bore 28\5 inc.

n° 2, .

20 calibres, . . .

. . 38-4

n° 3, .

30 calibres, . . .

. . 57-7

n* 4, .

40 calibres, . . .

. . SO-2

the calibre of each being 2-^ inches, and the medium weightof the balls 16 oz 13 drams.

6. The mediums of all the experimented velocities of theballs, with which they struck the pendulous block of wood,placed at the distance of 32 feet from the muzzle of the gun,for several charges of powder, were as in the following table,

Table of Init ial Velocities.

Powder.

The Guns.

OZ

N° 1.

N° 2.

N° 3.

N° 4.

2

780

835

920

970

4

1100

1180

1300

1370

6

1340

1445

1590

1680

8

1430

1580

1790

1940

12

1436

1640

*

•

14

*

1660

-

*

16

•

2000

*

18

*

•

•

2200

placed in the 1st column, for all the four guns, the numbersdenoting so many feet per second. Whence in general itappears how the velocities increase with the charges of pow-der, for each gun, and also how they increase as the guns arelonger, with the same charge, in every instance.

7. By increasing the quantity of the charges continually,for each gun, it was found that the velocities continued toincrease till they arrived at a certain degree, different in each