282 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 



round its axis. Was not the heat produced, or at least some part of it, occasioned 

 by this friction of the^ piston ? and, as the external air had free access to the extre- 

 mity of the bore, where it came in contact with the piston, is it not possible that 

 this air may have had some share in the generation of the heat produced ? 



Exper. 3. A quadrangular oblong deal box, water-tight, 114- English inches long, 

 g-jtg. inches wide, and Q-^- inches deep, being provided, withholes or slits in themiddle 

 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 was put into its place 

 was fixed to the machinery, in such a manner that its bottom being in the plane of 

 the horizon, its axis coincided with the axis of the hollow metallic cylinder; it is evi- 

 dent, from the description, that the hollow metallic cylinder would occupy the 

 middle of the box, without touching it on either side; and that, on pouring 

 water into the box, and filling it to the brim, the cylinder would be completely 

 covered, and surrounded on every side, by that fluid. And further, as the box 

 was held fast by the strong square iron rod which passed, in a square hole, in the 

 centre of one of its ends, while the round or cylindrical neck, which joined the 

 hollow cylinder to the end of the cannon, could turn round freely on its axis in the 

 round hole in the centre 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 the water out of it, or deranging any part of the apparatus. 

 Every thing being ready, I proceeded to make the experiment I had projected, in 

 the following manner. 



The hollow cylinder having been previously cleaned out, and the inside of. its 



bore wiped with a clean towel till it was quite dry, the square iron bar, with the 



blunt steel borer fixed to the end of it, was put into its place; the mouth of the 



bore of the cylinder being closed at the same time, by means of the circular 



piston, through the centre of which the iron bar passed. The box was then put 



in its place, and the joinings of the iron rod, and of the neck of the cylinder, 



with the two ends of the box, having been made water-tight, by means of collars 



of oiled leather, the box was filled with cold water, (viz. at the temperature of 



6o°) and the machine was put in motion. The result of this beautiful experiment 



was very striking, and the pleasure it afforded me amply repaid me for all the 



trouble I had had, in contriving and arranging the complicated machinery used in 



making it. The cylinder, revolving at the rate of about 32 times in a minute, 



had been in motion but a short time, when I perceived, by putting my hand into 



the water, and touching the outside of the cylinder, that heat was generated; and 



it was not long before the water which surrounded the cylinder began to be sensibly 



warm. At the end of 1 hour, I found, by plunging a thermometer into the water 



in the box, (the quantity of which fluid amounted to 18.77 lb. avoirdupois, or 1± 



wine gallons), that its temperature had been raised no less than 47 degrees; being 



now 107° of Fahrenheit's scale. When 30 minutes more had elapsed, or 1 hour 



