124 THE WINDAGE
mary direction wil] be altered, and it will pursue a fresh onecommunicated to it by the shock against the side of the gun,
CHAP. IV.
Of the Windage of Shot,
55. X H E hardness of bronze and iron, and the greatdifficulty of making cannon shot perfectly smooth and sphe-rical render it almost impossible that iron shot should be madeto fit a gun, with as much justness and precision as leadenbullets fit carabines; it is necessary therefore to allow whatis called windage ; and for that purpose to make the calibreof the gun greater than the diameter of the correspondingshot: the proportion between them must be such as to allowfor any little unevenness In the bore of the gun, or on thesurface of the shot, and to admit of its being drawn out bythe ladle, or other means, if by accident any extraneous bodybe lodged in the gun.
56. If fired powder followed a constant law, the windagecould be reduced to a fixed rule (55), so as to guard againstall contingencies; but as this law is subject great varie-ties, it is necessary to examine how far the increase or decreaseof windage contributes to the more sudden explosion of thepowder. Among the many experiments made in the Treatiseon Powder, to demonstrate the existence of these modifica-cations, there is one fm) which shews how much theforce of powder in musquets is affected by the size of thevent; the following experiment proves that its inflammationand effects are also modified by the windage of the shot.
57. In the month of July 1759, the Commander deViNCENTi, colonel of artillery, made the following experi-ments with two 16 prs. of the fame weight and length,but of different calibres: the calibre of A was divided into813 parts, and that of B into 819 of the fame parts; the gunswere fired horizontally mounted on their carriages upon plat-forms perfectly horizontal. The shot were of two kinds,and grazed on an even piece of ground about 5 feet belowthe axis of the gun; the shot of the first kind had the dia-imeter — C divided into 784 of the above mentioned parts,and weighed ^ lb. more than the proper weight; the diameter