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.

Reception of the New Physics

You tell me you would like to know the device by which I was able to assure myself that the vertically falling  body leaving from the rest passed 100 braccia of height in five seconds. Here two things are sought: the first is the time of descent through 100 braccia, and the second is to find what part that time is of 24 hours in the [del primo mobile].

When instruments disappear from view

No investigator did more to popularize the idealization of instruments and experimental conditions than Bessel. In addition to numerous applications of and elaborations upon the method of least squares, Bessel contributed significantly to the theory of astronomical and related instruments. Wanting to assemble a fixed star catalogue based on James Bradley's observations from 1750-1762, Bessel found he needed an alternative theory of refraction in order to refine Bradley's data.

George Graham

"Born in the parish of Kirklinton, Cumberland, July 7, 1673, of parents who were members of the Society of Friends. In 1688, he came to London, and was apprenticed to Henry Aske, Clockmaker, July 2 in that year. During his apprenticeship he made the acquaintance of the family of the celebrated Thomas Tompios, Watchmaker, of Fleet Street, who ultimately received him into his employ. He married Elizabeth the daughter of Tompion's brother James, and at his master's decease in November, 1713, succeeded to the business.