the Heat excited by Friction. 481 



Experiment No. 3. 



A quadrangular oblong deal box (see Fig. 4), water- 

 tight* ii| English inches long, 9^5- inches wide, and 9 T 6 g- 

 inches deep (measured in the clear), being provided with 

 holes or slits in the middle of each of its ends, just 

 large enough to receive, the one the square iron rod to 

 the end of which the blunt steel borer was fastened, the 

 other the small cylindrical neck which joined the hollow 

 cylinder to the cannon ; when this box (which was occa- 

 sionally closed above by a wooden cover or lid moving 

 on hinges) was put into its place, that is to say, when, 

 by means of the two vertical openings or slits in its two 

 ends (the upper parts of which openings were occasion- 

 ally closed by means of narrow pieces of wood sliding in 

 vertical grooves), the box (g, h y /, k, Fig. 3) was fixed 

 to the machinery in such a manner that its bottom (/, k) 

 being in the plane of the horizon, its axis coincided with 

 the axis of the hollow metallic cylinder; it is evident, 

 from the description, that the hollow metallic cylinder 

 would occupy the middle of the box, without touching 

 it on either side (as it is represented in Fig. 3); and 

 that, on pouring water into the box, and filling it to the 

 brim, the cylinder would be completely covered and sur- 

 rounded on every side by that fluid. And farther, as 

 the box was held fast by the strong square iron rod (m) 

 which passed in a square hole in the center of one of its 

 ends (a, Fig. 4), while the round or cylindrical neck, 

 which joined the hollow cylinder to the end of the can- 

 non, could turn round freely on its axis in the round hole 

 in the center of the other end of it, it is evident that 

 the machinery could be put in motion without the least 

 danger of forcing the box out of its place, throwing 

 VOL. i. 31 



