A Contrivance to avoid the Irregularities in a Clock's Motion, occasion'd by the Action of Heat and Cold upon the Rod of the Pendulum. By Mr. George Graham, Watch-Maker, F.R.S.

Whereas several, who have been curius in measuring of Time, have taken Notice, that the Vibrations of a Pendulum are slower in Summer than in Winter; and have very justly supposed this Alteration has proceeded from a Change of Length in the Pendulum itself, by the Influences of Heat and Cold upon it, in the different Seasons of the Year; with a View therefore of correctiong, in some degree, this Defect of the Pendulum, I made several Trials, about the Year 1715.