Tract 37.
OF GUNNERY.
271
equal to 3'3865 in the 1st column of the trtble, to which cor*responds the angle 3 4° I o’, being the elevation to produce-the greatest range ; and the corresponding number 3 054Q>in the 3d column, multiplied by 2729, gives 8336 feet, forthe greatest range, being rather more than a mile and ahalf.
121, Exam. 2. In like manner, the same ball dischargedtvith the velocity SCO feet, will have for its greatest range4081 feet, or above f of a mile, and the elevation producingit 40°.
122. Corollary. These examples, and indeed the wholetable in the 10th problem, are only adapted to the use ofcannon balls. But it is not usual, and indeed not easilypracticable, to discharge cannon shot at such elevations, inthe British service, that practice being the peculiar office ofmortar shells. On this account then it will be necessary tomake out a table of terminal velocities, and altitudes due tothem, for the different sizes of such shells. The severalkinds of these in present use, are denominated from the di-ameters of their mortar bores in inches, being the live fol-lowing, viz, the 4-6, the 5-8, the S, the 10, and the 13 inclimortars, as in the first column of the following table. Butthe outer diameters of the shells are somewhat smaller, toleave a little room or space for windage, as contained in the2d column.
Diam.
of
mortar
Diam.
of
shells
Wt. ofshellsempty
VVt. ofshellsfie ltd
Weightof equalsolid
Ratio ofshell tosolid
Terminal
velocity
Alt. adue toveloc.
inches
inches
lbs
lbs
lbs
feet
feet
4‘6
4-53
8-3
9
1 <?3
1-42
318
1580
5-8
5-72
16-7
18
25*
1-42
356
1980
8
7-90
43-8
47
67
1-42
420
2756
10
9-84
85-5
■ 91 *
130
1-42
468
3422
13
12-80
187-8
201
286
1-42
534
4430
The 3d column contains the weight of each shell when