Experiments iipon Gunpowder. 41 



different quantities of powder, the velocities are nearly 

 in the sub-duplicate ratio of the weights of the charges. 

 The following table will shew how accurately this law 

 obtained in the foregoing experiments : 



Charges. 



33 

 310 

 2 9 

 2l8 

 208 

 I6 5 

 145 

 104 



The computed velocities as they are set down in this 

 table were determined from the ratio of the square root 

 of 437-3- the weight, in grains, of the largest charge 

 of powder to the mean velocity of the bullet with 

 that charge and the vent at o, viz., 1764 feet in a 

 second, and the square root of the other charges ex- 

 pressed in grains. And the actual velocities are means 

 of all experiments that were made under similar circum- 

 stances with the given charges. 



The fourth column shews the difference of the com- 

 puted and actual velocities, or the number of feet in a 

 second by which the actual velocity exceeds or falls 

 short of the computed ; and in the fifth column is set 

 down the number of experiments with each charge 

 from the mean of which the actual velocity was deter- 

 mined. 



The agreement of the computed and actual velocities 

 will appear more striking if we take the sum and differ- 



