VOL. LXXI.] PHILOSOPHICAL TRANSACTIONS. 8Q 



the lengths of those chords, expressed in inches and decimal parts of an inch, 

 are set down in the tables. The method of computing the velocity of the re- 

 coil from the chord of the arc through which the barrel ascended, is too well 

 known to require an explanation : .and it is also well known, that the velocities 

 are to each other as the chords of those arcs. The lengths of those chords, 

 therefore, as they are set down in the tables, are, in all cases, as the velocities 

 of the recoil. 



The powder made use of in these experiments was of the best kind, such as is 

 used in proving great guns at Woolwich. A cartridge, containing 12 lbs. of 

 this powder, was given to Mr. T. by the late general Desaguliers of the Royal 

 Artillery. This powder was immediately taken out of the cartridge, and put 

 into glass bottles, which were previously made very clean and dry ; and in these 

 it was very carefully sealed up till it was opened for use. When it was wanted 

 for the experiments, it was weighed out in a very exact balance, with so much 

 attention, that there could hardly be an error in any instance greater than a 

 quarter part of a grain. The bottles were never opened but in fine weather, and 

 in a room that was free from damp, and no more charges of powder than were 

 necessary for the experiments of the day were weighed out at a time. Each 

 charge was carefully put up in a cartridge of very fine paper, and these filled car- 

 tridges were kept in a turned wooden box, that was varnished on the inside as 

 well as the outside, to prevent its imbibing moisture from the air. The paper of 

 which these cartridges were made, was so fine and thin, that 1280 sheets of it 

 made no more than an inch in thickness, and a cartridge capable of containing 

 half an ounce of powder weighed only 4 of a grain. The cartridges were 

 formed on a wooden cylinder, and accurately fitted to the bore of the piece, and 

 the edges of the paper were fastened together with paste made of flour and 

 water. 



When a cartridge was filled, the powder was gently shaken together, and its 

 mouth was tied up and secured with a piece of fine thread ; and when it was 

 used it was put entire into the piece, and gently pushed down into its place with 

 the ramrod, and afterwards it was pricked with a priming-wire thrust through 

 the vent, and the piece was primed ; so that no part of the powder of the charge 

 was lost in the act of loading, as is often the case when the powder is put loose 

 into the barrel : nor was any part of it expended in priming ; but the whole 

 quantity was safely lodged in the bottom of the bore or chamber of the piece, 

 and the bullet was put down immediately upon it, without any wadding either 

 between the cartridge and the bullet, or over the bullet. 



The bullets were all cast in the same mould, and consequently could not vary 

 in their weights above 2 or 3 grains at most, especially as care was taken to bring 

 the mould to a proper temperature as to heat before the casting ; and when 



vol. xv. N 



