In the year 1746, between the 7th February and the 30th March, a series of experiments were made by the offi cers of artillery at Turin, for the purpose of determining the charges of powder that give the largest ranges. The. guns were mounted on a part of the fortifications of the city, where the axis of the piece was 30 feet higher than the level of the country where the shot fell. The guns were fired with their axes always horizontal. The smallest charges were at first used, and increased gradually till the ranges began to diminish. The following table slims the results of the experiments : From these results it follows, that the charge of powder which gives the longest range is equal to half the weight of the shot in four and eight pounders, and to one-third of its weight in 16 and 32 pounders. The recoil always in creases in proportion to the augmentation of the charge. The length of the range increases to a certain point, and afterwards decreases in a much less ratio than the recoil increases. The charge which gives the longest range in pieces of small calibre, is proportionally longer than in pieces of large calibre.
In the spring of 1750, the Chevalier Ferrero di Ponsig lione made a series of experiments with pieces of the same calibre and proportions at Turin, for the purpose of ascer taining the charge that gives the longest range when the piece is fired at the greatest elevation its carriage will ad mit of. The ranges were measured on a flat piece of ground, nearly on the same level with the battery. The shot being rather larger, the windage was less than in the experiments of 1746.
From these experiments it follows, that the charges that give the longest ranges when cannon are fired from the great est elevations their carriages will permit, are greater than those which produce the same effect when they are fired hori zontally. Several experiments which were some time after wards made in France, sheaved, that in cannon of a large calibre, the charge should be about three-eighths of the weight of a shot. In the month of August 1747, Signior Marandone made a series of experiments for the same pur pose, by orders of the Knights of Malta. From these he concluded, that the charge that ought to produce the long est lane, must exceed three-eighths of the weight of the shot.
Signior Mattel, mathematical instrument maker to the King of Sardinia, invented a machine for finding the ini tial velocity of balls measured near the mouth of the gun; and a number of valuable experiments were made with it by Antoni, of which we shall afterwards give a more par ticular account. Mattes machine consists of a horizontal circle, supported by its centre on the upper end of a ver tical axis, and serving as a base to a hollow paper drum.
This drum is made to revolve by means of a weight at the end of a cord passing over a pulley ; and the projectile, thrown in a horizontal direction, traverses the paper drum in two points. The arc described by the system, while the projectile, in traversing the interior of the drum, is mea sured by the distance of the second point from the dia meter which passes through the first. See-the Descrip tion of Plates, and p. 179.
Another very simple machine for the same purpose was invented in 1764, by Lieutenat De Butet. " He applies a little plate of metal, provided with a moveable index, to any wheel that turns with an equable motion and sufficient velocity ; the index is held at some distance from the cir cumference of the wheel, by a thread that is stretched across the mouth of the gun. When the gun is fired, the shot breaks the thread and sets at liberty a spring, which in stantly presses the index against the wheel, upon which it describes an arch, till it is checked by the impact of the shot against a moveable butt placed at the distance of a few feet ; to this effect, one extremity of a rod is fastened to the butt, and the other to the plate ; thus the index is drawn back by the rod which follows the movement of the butt, and ceases to describe the arch on the circumference of the wheel. The motion of the wheel, the distance from the muzzle of the gun to the butt, and the arch described by the index being known, it is easy to ascertain the space that the shot passes through in one second of time with an uniform velocity ; or, in other words, its initial velocity. To diminish the friction as much as possible, a small groove is made in the part of the wheel that receives the index, and filled with grease, which presents a very slight resistance. By means of this instrument, the time of the shot's pas sage along the bore of the gun, the initial velocity of shells, and the resistance of the air to their motion, may be deter mined ; if allowance be made for the modifications that must ensue." In the year 1779, the learned Dr Hutton of Woolwich, in conjunction with several officers of artillery, undertook a series or —^riments on the motion of cannon balls. They used oallistic pendulums from 300 to nearly 600 pounds weight, and they employed cannon shot of I, 2, and 3 pounds weight, and they varied the charge of powder from 2 to 8 ounces, From these experiments, of which a full account was published in the Philosophical Transac tions for 1778, Dr Hutton deduced the following infer ences.