[ <4 ] 
chine which I contrived for the Purpofe, and got exe- 
cuted with great Nicety, not in Ornaments, but only 
where Nicety in a mechanical Inftrument ought to 
be obferved 5 a Caution ufeful in many other Ma- 
chines. 
In this Machine, the Iron Bar* or Parallelipiped 
reprefenting the heavy Body, weighs 12 Drams, 12 
Dwt, 12 Grains, or 6060 Grains, and its Centre of 
Gravity is at the Diftance of 20 Inches and a half from 
its Centre of Motion. 
The Props I make ufe of are, the one of five, and 
the other of ten Inches. To overcome the Fridion, 
allowed for by certain Rules in all Cafes, I ufe a nice 
Brafs Pully of three Inches Diameter, whofe Pivots 
are but ^ ols of an Inch in Diameter 5 fo that the 60th 
part of the Power added to it, will, in all Cafes, over- 
come the Fridion. 
First Case. 
In which the "Prop is perpendicular to the Horizon , 
exemplified by two Experiments . 
Experiment I. 
The Prop is equal to five Inches, and plac'd under 
a Point in the Bar 10 Inches diftantfrom the Centre 
of Motion. Here the Power ading in the Diredion 
of the Prop, able to keep the Bar in that Situation, 
or the Prefiure fuftain'd by the Prop, will be found 
2fo Ounces, 17 Dwt, iy Grains 5 and the Fridion 
8 Dwt, 1 y Grains. The Foot of the Prop is to be at 
% Inches and from the Centre of Motion. 
Ex- 
