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PHILOSOPHICAL TRANSACTIONS. 



[anno 1781 



leather was put about them, or otherbullets than those of lead were used, the weight 

 was determined very exactly before they were put into the piece. The diameter 

 of the bullet was determined by measurement and also by computation from its 

 weight, and the specific gravity of the metal of which it was formed ; and both 

 these methods gave the same dimensions very nearly. 



A Table showing the weights and dimensions of the principal parts of the apparatus. 



Of the barrel. 



Inches. 



Length 44,7 



Length of the bore from the muzzle to the breech- pin 43.45 



Diameter of the bore 0.78 



Thickness of metal at the lower vent 0.36" 



Thickness of metal at the muzzle 0. 1 



Weight of the barrel, with the breech pin, the vent-screws, and vent 

 tube, 6 lbs. 6 oz. 



Of the gun carriage. 



Length 28.4 



Distance between the two pair of trunnions 25.6 



Diameter of each trunnion 0.25 



Weight 40 lbs. 14 oz. 



Of the rods by which the carriage was suspended. 



Length from the axis of suspension, or centre of the pivots, to the centre of the trunnions of the 

 gun carriage, 6'4 inches. 



Weight of each rod, 1 lb. 4 oz. 



Total weight of the barrel and its carriage, with the allowance made for the weight of the 

 rods by which it was suspended, 48 lbs. This was its weight from experiment N g 3, to experiment 

 N° 123 inclusive. 



Of the bullet. 



Diameter 0.75 inch. Weight when of lead, 5S0 grains. 



Of the pendulum. 



Total length of the pendulum from the axis of suspension to the bottom of the circular plate. . 69. 5 



Diameter of the circular plate to which the targets were fastened 13. 



Distance between the shoulders of the pivots 3.8 



Diameter of the pivots 27 



Weight of the iron part of the pendulum 47 lb. 4 oz. 



Of the pendulum with the targets fixed to it, as it was prepared for making the experiments, and 



numbered. 



