' [ *54 J 
Fig. 3. The lever A of this engine is 2 feet 9 
inches from the upper part of the beam, to the cen- 
ter ot it's axis B placed underneath; and weighs, 
with it’s arch- heads, about 5 tons. When it was placed 
in a horizontal pofition, it required but 93 4 pound- 
to overcome the refiftance from fridtion in the pevets;- 
but when either end was deprefled 4 feet below the 
level, at which diftance the fprings are fixed, it re- 
quired 534 pound to be applied to the oppofite end 
to bring it back again : fo that a power =440.1 was 
required, on account of the center of gravity being* 
10 much changed by the pofition of the axis under- 
neath. 
Fig. 4. To avoid this general error, I had the axis 
B placed on the upper fide of the leaver, and fixed 
by proper bolts and fcrews to a bar of iron equally 
ftrong, placed underneath : and, in order to reduce 
the quantity of fridtion, which is in proportion to the- 
fpace rubbing on a dead furface in equal time, I had 
them made in the form b B, fig. 4, by which they 
are equally ftrong, though the rubbing part b , is but 
1 1 diameter ; fo that by changing only the form of 
the pevets, the fridtion is reduced to 4 of it’s origi- 
nal quantity. I applied two quadrants, D D, to each 
of thefe pevets, whofe radii are 2 feet 6 inches, by 
which the whole fridtion of the pevets b of the axis 
of the leaver, are transferred to the pevets d of the 
quadrants, which are 14 inch diameter. Thefe qua- 
drants are equal in effedt to wheels 5 feet diameter; 
the radius of which is 4 0 to the femidiameter of its pe- 
vet, and reduce the fridtion in the pevets of the qua- 
drants to _^-’ h part of w'hat it was in the pevets b of the 
axis; which x by 4 the reduction made by changing 
the form of the pevets by which means the 
fridtion 
