PHYSICAL anp LITERARY. 5 
only bring out a greater invariable force, 
which can never produce an. acceleration of 
motion. The acceleration therefore muft be 
attributed to gtavity alone, the force of 
which, in the beginning of the motion, is 
fuppofed to be lefs than any affignable quan- 
tity, whereby a body, {et in motion by the 
force of gravity, paffes through every de- 
gree of velocity from reft, till it acquire 
’ that velocity which it has when it touches 
the ground. | 
I have dwelt the longer upon this proper- 
_ ty of gravity, becaufe there is connected with 
it another property, which is, that in. mo- 
tion, the action of gravity is not to be con- 
fidered as one action exerted through a length 
of time, but as. a number of different ati- 
ons exerted inceffantly.. For, if the gravity 
of a body in motion continues not the, fame 
any two fucceflive moments, but is continu- 
ally varying, the a@ion muft vary with the 
power ; and confequently is not one, but a 
_ tumber of different actions. Gravity -in a 
’ body at reft, is, like the wis infita, one in- 
varied power, which ‘produces one - in- 
“varied ation exerted through a length of 
me. But, when once the body is put in 
iS oes H 
motion, 
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