32 ON THE HEAT PRODUCED BY* FRICTION*. 



to his Chemical Statistics, vol. J, p. 247*. Thus the opi- 

 nion of philosophers remains wavering between two theories 

 diametrically opposite, and each supported by respectable 

 Acquires fur- authority. Accordingly 1 have undertaken the following 

 mentstodetect ^P*tf*****» w ^ the view to add some facts to those, that 

 its source. will serve pe haps some day to elucidate more completely 

 this important question. The experiments of count Rum- 

 ford, executed on a large scale, were well calculated to 

 give rise to conspicuous phenomena; but they appear to 

 me, not to have been varied sufficiently. This is the object 

 I proposed to myself, not merely the rubbing of bodies of 

 different kinds, but likewise by varying all the circumstances 

 that could concur in the developement of heat. 

 Aponratus for The apparatus I employed consists of a small cubical 

 IS P r P • oa ken box, very firmly put together and cemented, in which 

 an axis turns vertically. The lower end of this axis rests in 

 a copper socket fixed to the bottom of the box, and on the 

 opposite end a grooved wheel is securely fastened. In the 

 upper third is a rim, resting on a bed of copper fixed to the 

 cover of the box: and to the lower third is fixed a piece of 

 copper furnished with rims, to retain cylindrical pieces of 

 metal fitted to it. These pieces are 6 cent. 5 mill. [2§ inches] 

 in diameter. On the convex surface of these hollow cylin- 

 ders, the friction is produced by means of a spring fastened 

 horizontally in the inside of the box. This spring receives 

 at one extremity rubbers of metal, which are fitted to it by 

 means of a groove ; while a screw, passing through the box, 

 gives the spring the tension necessary to press the rubber 

 against the surface of the cylinder. A graduated arch fitted 

 to the spring indicates in weights the force produced by its 

 tension. The rotatory motion, that produces the continual 

 friction, is given by an endless cord passing round the wheel 

 on the axis and the large pulley of an iron-turner's wheel. 

 The diameters of these are to each other as one to four, so 

 that the velocity of the smaller is four times that of the 

 larger, and by turning this only once round in a second, the 

 smaller will make four revolutions in this period; so that the 



• So it is in Rees's New Cyclopaedia, art. Caloric. Trans. 



axis, 



