VOL. LXXI.] PHILOSOPHICAL TRANSACTIONS. QQ 



In the 71st experiment the powder was also rammed, but the vent, instead 

 of being at the bottom of the bore, was at 1.3, and the velocity of the bullet 

 was very considerably diminished, being only at the rate of 1080 feet in a 

 second, instead of 127 6 feet in a second, which was the mean velocity with this 

 charge, and with the vent in this situation when the powder was rammed. See 

 experiments N° 43, 44, 45, and 46. 



When, instead of ramming the powder, or pressing it gently together in the 

 bore, it is put into a space larger than it is capable of filling, the force of the 

 charge is thereby sensibly lessened, as Mr. Robins and others have found by re- 

 peated trials. In the 30th experiment the charge, consisting of no more than 

 l65 grains of powder, was made to occupy 3.2 inches of the bore, instead of 

 1.45 inches, which space it just filled when it was gently pushed into its place 

 without being rammed ; the consequence was, the velocity of the bullet, instead 

 of being 1 100 feet in a second or upwards, was only at the rate of 914 feet in 

 a second, and the recoil was lessened in proportion. 



And hence we may draw this practical inference, that the powder, with which 

 a piece of ordnance or a fire-arm is charged, ought always to be pressed together 

 in the bore ; and if it is rammed to a certain degree, the velocity of the bullet 

 will be still further increased. It is well known, that the recoil of a musket is 

 greater when its charge is rammed than when it is not ; and there cannot be a 

 stronger proof that ramming increases the force of the powder. 



Of the relation of the velocities of bullets to the charges of powder by ivhich 

 they are impelled. — It appears by all the experiments that have hitherto been made 

 on the initial velocities of bullets, that when the weights and dimensions of the 

 bullets are the same, and they are discharged from the same piece by different 

 quantities of powder, the velocities are in the sub-duplicate ratio of the weights 

 of the charges very nearly. 



The following table will shew how accurately this law obtained in the fore- 

 going experiments. 



The computed velocities, as they are set down in this table, were determined 

 from the ratio of the square root of 4374 (the weight in grains of the largest 

 charge of powder) to the mean velocity of the bullet with that charge and the 



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