. 44 ). 
formed, there will be very little Inequality in the 
Motion, befides what proceeds from Heat and Cold. 
In making ufc of Qiiickfilver for a Pendulum, by 
varying the Diameter of the Velfel that coniains it, 
or the fhicknefs of the Rod of the Pendulum, whe- 
ther it be of Brafs or Steel, they may be reduced near- 
ly to an Equality as to the receiving, or retaining 
the linprehions of Heat or Cold, upon which the 
greater Regularity of the Motion depends; and parti- 
cular Care ought to be ufed to free the Mercury from 
all Blebs of Air, otherwife their great and fudden Ex- 
panfion, or Contradion, may caufe a confiderable Dif- 
order ; but the Air may as eafily be excluded in this 
Way, as in a Barometer, and the great fpecifick Gra- 
vity of Quickfilver, renders it a proper Material for 
the Weight of a Pendulum. 
FINIS. 
' I ". ■■I , 11 I . , 1 mtmmi 
LO N DO Nj Printed for W. and J. Inny s. Printers to 
the Koyal Society^ at the Weft End of St, Paul's Church^ 
Tard. 1726. 
