I. Account of pendulum experiments undertaken in the Harton Colliery being an account of experiments undertaken to determine the correction for the temperature of the pendulum

Abstract

Adverting to the circumstance that, in the Harton Experiment, there was a mean difference of 7° between the temperature above and below, and that a careful determination of the coefficient for temperature-correction was therefore necessary, the author describes the process by which the correction was now investigated by experiment on the same pendulums which were used in the Harton Experiment. Two rooms were selected at the Royal Observatory, Greenwich, having firm stone floors, and admitting of being heated, one by a stove in the room, the other by a hot-air-apparatus below. One pendulum was mounted upon its iron stand, with clock and other apparatus, in one room, and the other in the other room. Care was taken that the pendulums and their thermometers should be effectually protected from radiation. The two clocks were compared by carrying a chronometer from one to the other, and remarking the time of coincidence of beats; a method which admits of very great accuracy, when (as in this instance) the distance through which the chronometer is to be carried is small.