RELATIVE TO DIFFERENT PARTS OF GUNNERY. 171 



By a comparison of the last set of experiments made with the guns of greater tenacity 

 of metal, it appears that the bursting charges arc nearly as the square root of the Dumber 

 of balls inversely. And this would seem to be in accordance with the well-established 

 fact, that, with a constant pressure, the time required to move a weight through a given 

 distance, is as the square root of the weight. 



The results of the experiments with the first set of guns are in general the same as 

 those from the second set, although the deviation from the ratio of the square root of the 

 number of balls is more considerable. The variation, however, is not greater than what 

 might be expected from experiments of this kind. It will be perceived that some of the 

 results of the experiments which were given under the head of the first question are 

 repeated under the present head, and it may be proper to add, that the whole number of 

 guns burst in these experiments was fourteen, and the number of discharges about three 

 hundred. 



III. In reference to the third question, namely, what part of the gun is subjected to 

 the greatest internal pressure at the moment of the discharge, the following experiments 

 and observations are offered. For the purpose of ascertaining the relative pressure on 

 the different parts of the interior, a series of holes were drilled through to the bore along 

 each side of a number of the guns, and to these holes, in succession, a barrel six inches 

 long was strapped, at right angles to the length of the piece, so that the velocity of the 

 ball from this barrel, in different positions, would give the pressure required. The holes 

 were six inches apart, and in order not to diminish too much the strength of the gun, 

 those on one side were made in the middle between those on the opposite side. The 

 gun was immovably fastened to a large block of timber, and to determine the velocity of 

 the ball from the short barrel, and consequently the internal pressure, the whole was 

 accurately levelled, and a horizontal line drawn at the height of the axis of the gun, on a 

 target of pine plank placed at the distance often yards. The deflection of the ball from 

 this line being accurately measured by its mark on the target, the time of flight, and con- 

 sequently the velocity, could be approximately calculated on the principles of falling 

 bodies — also, for the sake of comparison, with the results furnished by the deflection-, 

 the depths of penetration of the balls into the pine plank of the target were accurately noted. 

 The charge of the gun in all the experiments was the same, and consisted of two ounces 

 of cannon powder, and one ball, placed in contact with the end of the cartridge. The 

 holes were alonjr the whole lemrth of the bore of the stun: the first one bein" at about two 

 inches from the end of the bore and a little behind the centre of the ball. Ten discharges 

 were made in succession with th< lateral barrel opposite the same hole, and the average 

 distance of the marks of all the balls on the target below the horizontal lines was taken 

 as the measure of deflection. The series with each hole was several times repeated until 

 the whole number of shots fired exceeded a thousand. 



The general result was, that the least deflection and the greatest penetration were pro- 

 duced when the side barrel was lired from the hole nearest the powder — that the velocity 

 diminished, in a ratio not determined, as the barrel was advanced towards the muzzle. 



