Abstract
A FRESH measurement has been made by Mr. T. C. Mendenhall of the acceleration of gravity at Tokio, an account of which appears in the American Journal of Science. The experiments were made after the accepted methods with Kater's and Borda's pendulums, the only novelty introduced being that of employing a chronograph in connection with a reliable chronometer to determine the time of vibration of the pendulum. At every sixtieth or hundredth vibration of the pendulum a light break-circuit apparatus placed beneath it was raised to just such a height as to be “thrown” by the pendulum at its lowest point of swing, thus enabling its rate to be calculated to the ten-thousandth of a second. Mr. Mendenhall considers his determinations to be more reliable than those of Professors Ayrton and Perry, which were made with a long wire pendulum; lie revises their calculations, altering their value of “g” from 9.7974 to 9.7979, and asserts that their calculation of the theoretical value by Clairaut's formula is wrong? and should be 9.7980, not 9.797 (metres). His own determinations give a mean result of 9.7984.
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Physical Notes . Nature 22, 521–522 (1880). https://doi.org/10.1038/022521a0
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DOI: https://doi.org/10.1038/022521a0