Pieces intended for shooting with ball, whether they be plain or rifled, ought to be of much more equal thickness from the breech to the muzzle, than those that are intended for shot, only. In every barrel, there is an undulating vibration communicated to the metal by the explosion. This is most remarkable in a thin barrel, and when the charge is great; and may be rendered very evident by the following easy experiment. Take a piece of fine steel or iron wire, that is tempered so as not to stretch readily; pass it once around the thin part of a barrel, and twist it tight. The piece being then charged and fired, the wire will be found burst asunder, or considerably untwisted. It is evident, that such a degree of vibration in the barrel, must have an effect upon the ball in its passage through it; and that the only means of preventing it, is, by having an additional quantity of metal in the barrel. and especially in the fore part of it. The same circumstance certainly obtains, though in a much less degree, in fowling pieces; and on this account, as well as on that of the recoil, a barrel which is strong enough to withstand any charge that is required, may yet have too small a quantity of metal in it.
