PHILOSOPHICAL TRANSACTIONS. 



291 



VOL. LXVIII.] 



the weight, length, and centres of gravity and of oscillation were the same as 

 when taken the former day before the experiments were made; the former balls 

 having been extracted, and the holes filled up with wood. 



Here the 1st shot is again so much smaller than the 2 following, that some 

 irregularity must have attended it, on which account no use can be made 

 of it. The mean between the 2d and 3d is 973; and between the 4th and 5th 

 the mean is 749; that is, the velocity of the ig±. ounce ball is 973, and that of 

 the 464- ounce shot 749 feet per second, which 2 numbers are in the ratio of 

 1.3 to 1. But the reciprocal subduplicate ratio of the weights (19^ and 46i) is 

 the ratio of 1.34 to 1: therefore, in this instance, the velocity of the heavier 

 shot is a little less than would arise from the inverse ratio of the square roots of 

 the weights of the shot. But the accurate ratio cannot certainly be drawn from 

 these numbers, on account of the doubtfulness of some of them, as before 

 observed. 



It is very remarkable, that in the experiments of this day, the mean velocity 

 with 2oz. of powder, is 973, whereas it was no more than 626 in the former 

 day with the same quantity of powder, though the balls were heavier with the 

 greater velocity in the ratio of I9 to 17 nearly. This remarkable difference 

 must be chiefly owing to the windage in the first course : and hence we may 

 perceive the great advantage to be gained by the use of balls approaching in pro- 

 portion nearer to the diameter of the bore of the gun than what is prescribed in 

 the present establishment. Possibly however some part of this difference might 

 be owing to some small inequality in the powder, as that which was used this day 

 was taken from the bottom of a barrel. Perhaps also some part of the effect 

 may be owing to the greater degree of ramming which the powder had in this 

 course. 



The 3d course was made on the 12th of June, 1775, being a clear, dry, and 

 calm day. The powder in the experiments of this day was rammed in the same 

 degree as in the last. It was also nearly the same in the succeeding days, as 

 may be perceived by inspecting the 4th column of each course, which, denoting 



p p 2 



