Handbook for Light Artillery

by A. B. Dyer

A mean range is taken from those two which determined the long fork for the next shot, and then another shot is fired at a range obtained by taking the mean of the last range and the one of the long fork whose shot fell on the opposite side of the target. So proceed until the target is enclosed between two consecutive shots only 50 yards apart. This is called "the short fork, or bracket." Then a verifying group, generally a shot from each gun is fired with the elevation corresponding to the mean range of the short fork. If four out of six of the shots fall short, the range is established; and if shrapnel-fire is then resorted to the range is still further reduced by 50 yards. When the range has been measured, and not estimated, the short fork may be obtained from the first two shots.

If the elevation has not been obtained as above indicated, at known ranges shrapnel-fire may commence, as if the range had already been determined by shell-fire; at unknown ranges the trial-shot firing with shrapnel is conducted as with shell; that is to say, the elevation is increased or reduced from shot to shot (by 100 yards at short range, 200 yards at medium range) until the target is enclosed between at least two accurately observed shots, one over and the other short. The difference is reduced as already described until the mean of the short fork is obtained. The large fork should be established by percussion-shrapnel, and then fire time-shrapnel.

During the ranging platoon commanders indicate exactly the point to aim at, see that the sights are properly set, especially during the first rounds, observe similarly the time-fuze, and make any necessary correction for deflection; which deflection pertains to a particular gun, and is not carried to another. Bear in mind that each unit of the scale for deflection corresponds to ¹/₃₄₅ of the range for sights now used.[9]

After the ranging has been completed, if a gun makes a constant error, the platoon commander may be permitted to change the elevation ± 25 yards.

The general rule for vertical and lateral corrections is: when the deviation exceeds the amount of mean dispersion, a correction should be made after one round; but if it is equal to or less than this several rounds are fired with the same elevation or deflection, and a correction made according to their mean deviation.

The battery commander indicates the length of fuze for time-shrapnel.

If firing at artillery and all the guns are equally conspicuous, the fire should be directed upon one of the central guns, otherwise at the most conspicuous gun; if the wind is blowing across the range, the fire should be directed upon the most conspicuous gun on the windward flank. If firing upon masses of troops, the fire should be directed upon the centre of the first line; if firing upon skirmishers, it should be directed first upon one point, then another, close in front of the line.

PROJECTILES TO BE USED.

Percussion-shell.—For ranging, against material, and in default of shrapnel against living targets.

Against troops behind loopholed walls,—if it explodes after passing through, use percussion-shrapnel,—stockades, abattis, barricades, entanglements, etc.