the Source of the Heat excited by Friction . yi 
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 circu- 
lar piston, through the centre of which the iron bar passed. 
This being done, the box was put in its place, and the join- 
ings 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 6 o °. ) 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 
18.771b. avoirdupois, or 2^ wine gallons,) that its temperature 3 00 '32 
N 2 
C. d 
~ /C ’ J'hnt faA 
