n 6 Experiments to determine 



The annexed drawings will give a complete idea of 

 the whole apparatus made use of in these experiments. 

 A (Fig. i) is a solid block of very hard stone, 4 feet 

 4 inches square, placed upon, a bed of solid masonry, 

 which descended 6 feet below the surface of the earth. 

 Upon this block of stone, which served as a base to 

 the whole machinery, was placed the barrel B of ham- 

 mered iron, upon its support C, which is of cast brass, 

 or rather of gun-metal ; which support was again placed 

 upon a circular plate of hammered iron D, 8 inches in 

 diameter, and \ of an inch thick, which last rested upon 

 the block of stone. The opening of the bore of the 

 barrel (which was placed in a vertical position, and 

 which was just \ of an inch in diameter) was closed by 

 a solid hemisphere E of hardened steel, whose diameter 

 was 1. 1 6 inch; and upon this hemisphere the weight F, 

 made use of for confining the elastic fluid generated 

 from the powder in its combustion, reposed. This 

 weight (which in some of the most interesting ex- 

 periments was a brass cannon, a heavy twenty-four 

 pounder, placed vertically upon its cascabel), being fixed 

 to the timbers G G which formed a kind of carriage for 

 it, was moveable up and down ; the ends of these timbers 

 being moveable in grooves cut in the vertical timbers 

 K K, which being fixed below in holes made to receive 

 them in the block of stone, and above by a cross-piece 

 L, were supported by braces and iron clamps made fast 

 to the thick walls of the building of the arsenal. 



This weight was occasionally raised and lowered in 

 the course of the experiments (in placing and removing 

 the barrel), by means of a very strong lever, which is 

 omitted in the drawing to make it less complicated. 

 The barrel, a section of which is represented in Fig. 2 of 



