[ '54 ] 
dulum of N® 2. when left at Reft, would be fet a go- 
ing by the Motion of N® i. whereas if N® i. was left 
at Reft, it would npt be fet a going again by the Mo- 
tion of N® 2. 
For I found by feveral Experiments, that the fame 
Pendulum, when kept in Motion by a Weight, would 
go fafter, than when it only moved by its own Gra- 
vity. On this Principle, which may eafily be ac- 
counted for, it follows, that during the Time in which 
the fhorteft Pendulum, N® 2. was only afted upon by 
N° I. it would move flower, and the Times of its 
Vibrations approach nearer to an Equality with thofe 
of N® I. than after it came to be kept in Motion by 
the Weighty and by this means the Time which i. 
would continue to a£t upon it, would be prolonged, 
and be more than was required to make the Pen- 
dulum deferibe ah Arch fufficient to fet the Work 
a going. But on the contrary, while the Pendulum 
of N° I. which was the longeft, was only aded upon 
by N° 2, as it would move flower, the DiflFercnce of 
the Times of the Vibrations would be increafed> 
and confequently the Time which N° 2 . would con- 
tinue to aft upon it, would for this Caufe be fliort- 
cned, fo that before the Pendulum of N® i. would 
deferibe an Arch fufficient to fet the Work a going, 
the Period of its being afted upon would be ended, 
and it would begin to aft upon N° 2. at which time 
its Vibrations would immediately decreafe, and con- 
tinue to do fo till it came to bealmoft at Reft. And 
thus it would continue fometimes to move more, and 
at other times lefs, but never fufficiently to fet the 
Clock a going. 
This 
