EiGBY — On the Velocity and Energy of Small Shot. ' 27 



550 feet per second, wliile an expert, who had published several 

 books on guns, affirmed that the mean velocity of the charge in 

 the first 40 yards was 1200 feet per second. 



In this state oi the question I determined to measure, by means 

 of the " Boulenge" chronograph, the actual time of flight for 120 

 feet from muzzle. To enable me to do so, one of those instruments 

 was placed at my disposal by Messrs. Pigou, Wilks, and Lawrence, 

 the eminent gunpowder manufacturers at Dartford, and I found 

 their apparatus quite suited to the purpose. The interval was 

 measured between the rupture of a fine wire stretched across the 

 muzzle, and the movement of an iron target hung on an axis, in 

 such a manner that the impact of a considerable portion of the 

 charge was necessary to effect the interruption of contact. In this 

 way the velocity of the average pellet in the charge was more 

 nearly approached than if the second interruption had been made 

 by a single pellet, which might have a velocity considerably above 

 the average of the whole charge. 



Since this Paper was commenced a communication has appeared 

 in the Field from the pen of Major M'Clintock, giving results 

 of numerous experiments made at the Enfield factory on the velo- 

 city of small shot. 



Major M'Clintock has also used the Boulenge chronograph, 

 but has rendered his results less satisfactory by employing as his 

 second screen the frame with wires stretched over it, which is 

 commonly used when the velocities of rifle bullets are investigated. 

 He confesses that his results are affected by this obvious error, and 

 that it is a matter of chance altogether whether the current at the 

 second screen is interrupted by the quickest or by the slowest pellet 

 in the charge. 



The series of shots fired by me at Dartford gave the velocities 

 in the following Table as those of the respective charges of shot at 

 sixty feet from the muzzle. I am entitled to state this, because, 

 although the chronograph only gives the time taken by the shot to 

 traverse the observed interval, it has been shown that if the resist- 

 enc3 of the air varies as V^, the velocity at the middle point of a 

 short range is denoted by dividing the range in feet by the time 

 in seconds. 



As therefore it has been proved experimentally thiat the resist- 

 ance does vary approximately as the cube of the velocity, I am 



