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Gunnery is the science of conducting the fire of artillery. Gunnery may be divided into the theoretical and practical branches. The former consists chiefly in the application of mathematics to the solution of the problems in dynamics involved in the consideration of the motion of shot through the air, and is essential to the design of good systems of rifling and well-proportioned projectiles.
Practical gunnery, which deals with the actual firing, has reference rather to the use of individual guns than to the handling of artillery on a large scale. The line taken by a projectile in its passage through the air to the first point of impact is called its trajectory. This is always a curve, since though the force of the powder tends to propel the projectile in a straight line, the force of the earth's gravity begins to drag it down on leaving the gun; the trajectory is also subject to modifications caused by the resistance of the air, the form of the shot, etc. Among things to be considered in gunnery are the velocity of the projectile, initial and subsequent, the angle of elevation of the piece, the range or distance to which the projectile is carried, etc.
The trajectory is more curved with a low-velocity gun than with a high-velocity one; hence to obtain the same range the former must have a greater angle of elevation above the horizontal plane. To allow for the fall of the projectile it is necessary to point the axis of the bore of the gun as much above the mark aimed at as the projectile would have fallen below if the gun had been pointed Straight. Hence the use of sights both for small arms and heavy guns. The latter have usually what is called a 'tangent scale' at the breech and a foresight at the muzzle to enable the piece to be aimed suitably. In order to know how to aim a gun so as to hit an object, its range or distance must be found. This may be done by trial, that is by firing several experimental shots; but special instruments known as range-finders have been in use since the start of the 20th century, the principle on which they are constructed being that of measuring the angle subtended at the object by a known base - the base being at the instrument itself.
In determining the velocity of projectiles various instruments were formerly used. Among these were Wheatstone's electro-magnetic chronoscope, the Bashforth chronograph, the Noble chronoscope, etc.
Horizontal fire against the front of a column or line of works is termed direct fire ; that which sweeps along a line of men or earth-works, enfilade fire, high angle and vertical fire is when the piece is fired at a high angle of elevation.
 Research Gunnery
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Abbreviations
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