Experiments upon Gunpowder. 13 



bewail casting ; and when leather was put about them, 

 or other bullets than those of lead were made use of, the 

 weight was determined very exactly before they were put 

 into the piece. 



The diameter of the bullet was determined by meas- 

 urement, 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. 



The apparatus was put up for making the experiments 

 in a coach-house, which was found very convenient for 

 the purpose, as the joists upon which the floor overhead 

 was laid afforded a firm and commodious support for 

 suspending the pendulum and the barrel, and the walls 

 and roofs of the building served to screen the apparatus, 

 which otherwise might have been disturbed by the wind, 

 and injured by the rain and dews. A pair of very large 

 doors, which formed the whole of one end of the room, 

 were kept constantly open during the time the experi- 

 ments were making, in order to preserve the purity of 

 the air within the house, which otherwise would have 

 been much injured by the smoke of the gunpowder, 

 which might, possibly, have had some effect in lessen- 

 ing the force of the powder, and vitiating the experi- 

 ments. In order still further to guard against this 



o o 



evil, the barrel was placed as near as possible to the 

 door, and the pendulum was hung up at the bottom of 

 the room. 



Fig. 12 represents the apparatus as it was put up for 

 making the experiments. 



a, b> is the barrel with its carriage, suspended by the 

 pendulous rods r, d y and 



R is the ribbon which served to measure the ascend- 

 ing arc of its recoil. 



