Bodies affeSied by Friction. 
2 67 
, ^diy, Whether the friction varies in proportion to th$ prejfure 
or weight. 
4thly, Whether the fridiion be the fame on whichever of its fur- 
faces a body moves. 
The experiments, in which I was aflifted by my ingenious 
friend the Rev. Mr. Jones, Fellow of Trinity College, were made 
with the utmoft care and attention, and the feveral refults 
agreed fo very exactly with each other, that I do not fcruple to 
pronounce them to be conclulive, 
2. A plane was adjufted parallel to the horizon, at the extre- 
mity of which was placed a pulley, which could be elevated or 
deprefled in order to render the firing which connected the 
body and the moving force parallel to the plane. A fcale accu- 
rately divided was placed by the fide of the pulley perpendi- 
cular to the horizon, by the fide of which the moving force 
defcended ; upon the fcale was placed a moveable flage, which 
could be adjufted to the fpace through which the moving force 
defcended in any given time, which time was meafured by a 
well regulated pendulum clock vibrating feconds. Every thing 
being thus prepared, the following experiments were made to 
afcertain the law of friflion. Rut let me firft obferve, that if 
friflion be a uniform force, the difference between it and the 
given force of the moving power muff be alfo uniform, and 
therefore the moving body muff defcend with a uniformly ac- 
celerated velocity, and confequently the fpaces defcribed from 
the beginning of the motion muff be as the fquares of the 
times, juft as when there was no fri&ion, only they will be 
diminilhed on account of the fridtion. 
3. Exp. i, A body was placed upon the horizontal plane, 
and a moving force applied, which from repeated trials was found 
to defcend 52 \ inches in for by the beat of the clock and 
7 the 
