IV. A contrivance to avoid the irregularities in a clocks motion, occasion'd by the action of heat and cold upon the rod of the pendulum

Whereas several, who have been curious 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