A HISTORY OF SCIENCE 



"This cylinder being designed for the express pur- 

 pose of generating heat by friction, by having a blunt 

 borer forced against its solid bottom at the same time 

 that it should be turned round its axis by the force of 

 horses, in order that the heat accumulated in the cylin- 

 der might from time to time be measured, a small, 

 round hole 0.37 of an inch only in diameter and 4.2 

 inches in depth, for the purpose of introducing a small 

 cylindrical mercurial thermometer, was made in it, on 

 one side, in a direction perpendicular to the axis of the 

 cylinder, and ending in the middle of the solid part of 

 the metal which formed the bottom of the bore. 



"At the beginning of the experiment, the tempera- 

 ture of the air in the shade, as also in the cylinder, was 

 just sixty degrees Fahrenheit. At the end of thirty 

 minutes, when the cylinder had made 960 revolutions 

 about its axis, the horses being stopped, a cylindrical 

 mercury thermometer, whose bulb was -ffa of an inch 

 in diameter and 3^ inches in length, was introduced 

 into the hole made to receive it in the side of the cylin- 

 der, when the mercury rose almost instantly to one 

 hundred and thirty degrees. 



" In order, by one decisive experiment, to determine 

 whether the air of the atmosphere had any part or not 

 in the generation of the heat, I contrived to repeat the 

 experiment under circumstances in which it was evi- 

 dently impossible for it to produce any effect whatever. 

 By means of a piston exactly fitted to the mouth of the 

 bore of the cylinder, through the middle of which pis- 

 ton the square iron bar, to the end of which the blunt 

 steel borer was fixed, passed in a square hole made per- 

 fectly air-tight, the excess of the external air, to the 



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