The artillerist's manual and British soldier's compendium

by F. A. Griffiths

By experiments it will be found that the greatest range (instead of being constantly that at an elevation of 45°, as in the Parabolic theory), will be at all intermediate degrees between 45° and 30° (with ordinary charges about 42°), being more, or less, both according to the velocity, and the weight of the projectile; the smaller velocities, and larger shells ranging farthest when projected almost at an elevation of 45°; while the greatest velocities, especially with the smaller shells, range farthest with an elevation of about 30°. However, as sufficient experiments have not yet been made to establish true rules for practical gunnery, independent of the Parabolic theory, we must at present content ourselves with the data of some one certain experimental range, and time of flight at a given angle of elevation, and then, by help of these, and the Parabolic theory, we can determine the like circumstances for other elevations that are not greatly different from the former, assisted by the following rules:—

PRACTICAL RULES IN GUNNERY.

1.—To find the Velocity of any shot, or shell.

It has been found by experiments, that with shot of mean windage, and powder of mean strength, a charge of one-third of the weight of the ball gives an initial velocity of about 1600 feet per second: therefore, to find the velocity given by any other charge, divide three times the weight of the charge by the weight of the ball, and multiply the square root of the quotient by 1600, the product will be the velocity in feet, or the space the shot passes over in the first second.[28]

2. The first graze, with given elevation, and charge, being known, to determine the charge for any other first graze, and elevation.

Multiply the known charge, and elevation into the proposed first graze, also the proposed elevation into the known first graze, and divide the first product by the last, for the charge required in ounces.

3. Given the range for one charge, to find the range for another charge, or the charge for another range.

The ranges have the same proportion as the charges; that is, as one range is to its charge, so is any other range to its charge, the elevation of the piece being the same in both cases.

Table of Velocities, &c., of shells.