322 MEASURING THE STRIKING FORCE OF SHOT. 



strengtliened by an observation of the striking differ- 

 ence in penetration displayed by the same gun at 

 different discharges. Let us take for instance the gun 

 entered by Mr. Hast, of Colchester, in the " Field'' 

 trial of 1866. At the first shot with the right barrel, 

 32 sheets were penetrated, the second 23, the third 

 only 15, while at the fourth 23 was again scored. In 

 the '' Field" trial of 1875, differences of 10 to 15 

 sheets were made at different discharges with the 

 same gun. 



For measuring the strength of shooting in the 

 " Field" gun trials of this year, 1879, a new target 

 has been employed, consisting of a steel plate or disk 

 backed by a spring, and connected with a graduated 

 scale upon which is indicated and registered automat- 

 ically the distance to which the disk is driven back by 

 the force of the pellets. The points upon this scale 

 are supposed to represent certain numbers of force- 

 ounces, as the units of measure have been termed, and 

 their positions were determined by striking the disk 

 with ash hammers of various known weights and 

 moving with definite velocities. Thus the eight force- 

 ounce mark represents the effect of the blow of a 

 hammer weighing one ounce, and moving at the rate 

 of eight feet per second ; the sixteen mark- that of a 

 two-ounce hammer with eight feet velocity ; the 24 



