Variation in the Density of Loading.—This is beyond the province of the cannoneer, and need not, therefore, be considered.
Bad Aiming.—To obviate this, the men found to have the necessary quickness of hand and eye should be utilized for this work, though all should receive instruction in aiming. The sight should be carefully examined before each shot, the same amount of the target should be brought into the angle of the cross-wires, and a constant distance between the eye and the rear sight should be maintained.
Faults in Handling Ammunition, Fuzes, etc.; Variable Weights of Cartridges and Projectiles; Failure to Take into Account the Age and Condition of the Powder.—Cartridges should be weighed, gauged, and felt when received; otherwise there will be variations in range due to more or less powder, to the make of the cartridge, or to caking. If the cartridges of a battery vary much as to age, brand, etc. or if they have travelled much, it would be well, when opportunity offers, to break the lot up, mix the powder thoroughly, remake and reweigh them. Be careful to use the copper measures and funnels, which can be obtained from the Ordnance Department.
Time-fuzes are sometimes carelessly cut, or the safety-pin not removed.
Inability to Judge Correctly the Position of Bursts of Projectiles.—The needful correction in elevation and fuzes cannot be given unless it can be seen by the eye or glass, or by the aid of observers, how the shells are bursting. While no provision has been yet made therefor, a good telescope, with a tripod, and capable of being moved by a micrometer screw, should be supplied to each battery in service.
In making allowance for the wind move the sight into the wind; e.g., if the projectile is carried too far to the right, on account of the wind blowing from the left, move the sight to the left, and vice versa.
ESTIMATING DISTANCES.
The light, the state of the atmosphere, and the nature of the ground are the chief disturbing causes in estimating distances and admit of no rules.
The sun on one's back, a light background, water or snow to look over, ground that is uniform and offers no prominent points of reference, or when the air is particularly clear, as after a rain, tend to make objects appear near.
A dark background, the sun in one's eyes, undulating ground to look over, or when it is cut by ravines or covered by trees or dwellings, or seen dimly at evening and in misty weather, tend to make objects appear distant.