94 l'HILOSOPHICAL TRANSACTIONS. [ANNO 1781. 



of the bullet 580 grains. This gun carriage being found to be too light, another 

 was substituted in the room of it. 



To determine how much of the force of the powder was lost by windage and 

 by the vent, oiled leather was fastened round the bullet, so that it now accu- 

 rately fitted the bore of the piece; and in the 5 experiments, from N° 35 to N° 

 3Q inclusive, the valve-vent was made use of. Weight of the bullet, in the ex- 

 per. 3 to 24, with the leather in which it was enveloped, 603 grains. 



Finding that the blast of the powder always reached as far as the pendulum, 

 when large charges were used, and suspecting that this circumstance, with the 

 impulse of the unfired grains, might in a great measure occasion the apparent 

 irregularity in the velocities of the bullets; to remedy these inconveniences, a 

 large sheet of paper of a moderate thickness was stretched on a square frame of 

 wood, and interposed as a screen before the pendulum at the distance of 2 feet 

 from the surface of the target, in the exper. 25, 31. The screen was found to 

 answer perfectly well the purpose for which it was designed, and it was continued 

 during the remainder of the experiments, the paper being replaced every 3d or 

 4th experiment. 



The bullets were now put naked into the piece, exper. 32, 39, and the powder 

 was lighted by the short vent-tube, and some little improvement was made in the 

 steel edges between which the ribbons passed that served to measure the ascend- 

 ing arcs of the pendulum and of the recoil, by which means the friction was 

 lessened, and the ribbon was prevented from twisting or entangling itself as it 

 was drawn out. 



The apparatus, commencing exper. 40, the barrel with its carriage as before; 

 the pendulum, N° 3, and leaden bullets, weighing 580 grains each. 



The experiments N° 78, 79' 80, an d 81, were made in hopes of being able to 

 discover a method of adding to the force of gunpowder. Twenty grains of the 

 substances mentioned in the remarks on each experiment were intimately mixed 

 with the powder of the charge. In the experiment N° 82, a large wad of tow 

 well soaked in etherial spirit of turpentine, was put into the piece immediately 

 on the bullet: and in the experiment N° 83 a wad, soaked in alkohol, was put 

 into the piece in like manner. 



In the 9 experiments, viz. from N° 84 to N° 92 inclusive, the valve-vent was 

 used, and the bullets were made to fit the bore of the piece very exactly by means 

 of oiled leather, which was so firmly fastened about them that in each experiment 

 it entered the target with the bullet. 1'he bullet used in experiment N°85, was 

 of wood. Those used in the experiments N° 86 and N° 87, were formed in the 

 following manner: a small bullet was cast of plaistcr of Paris, which beino- 

 thoroughly dried, and well heated at the fire, was fixed in the centre of the 

 mould that served for casting all the leaden bullets used in these experiments; 



