{ ) 
V. An Experiment to jhew that the Fridlion of 
the federal Tarts in a Compound Engine, may 
he reduced to Calculation j by drawing Confe- 
rences from fome of the Experiments Jhewn be- 
fore the Royal Society lajl Year , upon fimple 
Machines , in Various Cir cum fiances, by me. Pious 
exemplified by the Fri&ion in a Combination of 
Pullies. J.T.Defaguliers. Jan. 14,173!. 
T HE Machine confifts of three Pullies (two up- 
per and one lower, or a Tackle of Three) 
whofe Diameters are exaftly as follows, i Inches, 
1 t Inch, 1 ^ Inch j and all the Center Pins of \ Inch 
Diameter : The Rope being of to Inch in Diameter. 
The Weight is 18 Pounds Averdupois, andconfe- 
quently the Power to keep it in /Equilibria muftbe 
= 6 ft>, and a very little more muft make the Power 
raife the Weight, if there was no Fridion j but here 
no lefs than ao Ounces are required, though the Ma- 
chine is as nicely made as it can poflibly be. 
I have (hewn by Experiment, that when theWeight 
is unkown, f of the Power is die Friction of a Cy- 
linder whofe Surface moves as fall as the Power, 
and whofe Gudgeons are equal in Diameter to the Cy- 
linder. Now as the Diameter of the firft Pulley is 
eight times bigger than its Pin, its Fridion muft 
be i^-or 8 Ounces. 
0 
The fecond Pulley, whofe Surface moves as flow 
again as the Power, and whofe Pin is fix times lefs 
in 
