FRICTION. 
Ja:Hire — hhimfelf tothe rationale . ie thing ; and 
“has: given phyfical. folution = the And M. 
Amontons ve ee a calculus of the le of fri€tion ; 
and the lofs fuftained by it in machines, on the foundation 
.of the new principle. 
In wood, aa lead, . 
machines, he finds the refiftance, caufed 
a very {mooth ey- 
gar e lai do on two well-polifhed 
and oiled or greafed (ae Cc — , and be charged 
ti 
and ‘brafs, which are the ga Sa 
t 
‘the centre: and, for the fame’ reafon, the teeth of dented 
The following general propofition 
e de duced from the ifsc s remarks, viz. That 
eto one another in 
d the times or velocities of their motions. The expe- 
riments 0 . Amontons were confirmed by Boffut 
and Belidor. a7 chit. Hydraul. v. i. c. nd t i ¢ 
of M. Bulfin Comment. Petropol. tom. ii.) furnifhed 
conclufions ae to thofe of Amontons, with this differ- 
with the weight of two pounds -in the two equal balls together. . Parent, fuggefting that friction is occafioned 
G,H; it will require an additional “weight x (equal to by finall fpherical emine in one furface being dragged 
about - a part of the to pounds) to motion to, Out of correfponding {pherical eavities in the other, pro- 
or overcome the friction = the faid extn. But this pofed to - termine its quantity by finding the force which 
atl weight, as it caufes a greater preflure of the would move a {phere ftanding upon three equal fpheres. 
cylin will increafe the friGtion, aid: alae ie = Accordingly this force was found to be to the weight of the 
of another weight Ds ec wal to a thi of xt {phere as leven to twenty, or nearly one-third . = vag s 
ae 
jus omittin 
of additional ae x f i z, &c. equal to one pound: 
fo that if the weight of the cylinder be inconfiderable, the 
way to overcome the friction will be to double the power G 
or H at one 
But- if the cylinder moved on the two {mall gudgeons E 
and F, or ona {mall axis, the — boa ted in 
he fame proven as the diameter of thefe pee ‘ole {s 
than the diameter of the i. becanfe in this cafe the 
parts on which the cylinder moves and rubs will have lefs 
velocity ‘than the Poe which moves it in the fame pro- 
portion. See WHEEL Carriages. 
Befide the prefion, ne ‘magni alae whereof a 
that of the fri friction, there is another circumftan c 
z. the poe: ry. The frigtion is i anrere 
and the more difficult to furmount, as the parts are rubbed — 
againft each other with the greater fwiftnefs; fo that this 
velocity-muft b 
ne, and overcome the friction. 
Jeff 
cea againft each other ; ie ce ae of a circular 
n always gee e8- diminifhing from the circumference to 
e compared with that of the power ne- - 
° ~ = tang.a 
fr iétion, the weight o 
in oe a. 
feel (Recherches de Mathem, et Phyf. 1713. tom. ii.) 
n es g the casted of friGiion, M. Pom placed 
the body upon an inclined p 
nifhed the angle 
to move, and che an 
called the angle of prin 
e of equilibrium. (Mem. de 
e o. have 
adopted the hypothefis of Bulfinger refpeéting the ratio of 
friction to the force of preffion ; and 1 in two curious differ- 
tention of p profeffor Vince. ur le 
Solides ; and Sur la Dimi imution de 
ment, pabitaed: in the Memoires de l’ Acad. es Sec. 
& Berlin. ann. 1748. e obferves, that w rey a body i is in 
motion, the effect of as will be only one-half of what 
itis when the bo 
to its weight or preflure upon the plane, as the fine of the 
plane’s elevation is to its cofine, or as the tangent of the fame. 
angle is to radius, or as the height of the plane is to its 
ength. But when the body is in motion, the friftion is di- 
minifhed, and ia be found by the following equation, 
156230 aa a? in which y is the quantity of 
reflure of the body being = 1, 
a is the angle of the eine 8 saa mis the length of. 
the plane in zooodth parts of a Rhinland foot, and 2 the ~ 
sine to a caufe of friction, 
if otwithitanding all the counue ae and illuftrations of: . 
the 
