2-913-907 - The Print Collector/Heritage Images

Pendulum-Room at the Bottom of the Harton Coal-Pit, 1854. Experiment to determine the weight of the Earth. 'The apparatus consists of two astronomical clocks with compensation pendulums, two invariable pendulums (Kater's) suspended...immediately in front of the clock pendulums. An astronomical clock, and an invariable pendulum were placed at each station with barometer and thermometer attached, which were regularly observed, so that the necessary corrections might be made for atmospheric resistance, variations of temperature, &c. There was also at each station a galvanic-signal-needle...connected by...insulated wires, placing the observers in electric communication. The upper and lower stations...were exactly in a vertical line, and distant nearly a quarter of a mile; and at each station the instruments were carefully enclosed to prevent the vibrations of the pendulums being affected by currents of air'. From "Illustrated London News", 1854.