Account of pendulum experiments undertaken in the Harton Colliery, for the purpose of determining the mean density of the earth, by G. B. Airy
32 <s>34</s>. The number given by this table is the logarithm of the mean rate of the Detached Pendulum upon the Clock Pendulum under the actual circumstances of observation. It is next required to investigate the correction to this logarithm depending on the <s>[?]</s> extent of the arc of vibration: on of the conditions of the data of he problem being, that the <s>center of the</s> arc is observed only at the beginning and the end of the Swing. In the first place, to <s>[?]</s> compute the correction to the logarithm, supposing the arc of vibration constant. Let the whole arc of vibration, as seen upon the scale of inches, be I. For the pendulum 1821, suppose the scale to be placed 1 inch behind the pendulum, and for the pendulum 8, 1.8 inch behind the pendulum. <s>[?]</s> <s>[?]</s> And suppose the distance of the object glass of the observing telescope to be 100 inches. Then the real whole arc of vibration is I x 100/101 for pendulum 1821 and I x 100/101.8 for pendulum 8. The lengths of the two pendulums, from the knifeedge to the indicating point of the tail, are respectively 60.7 and 60.2 inches. Hence the proportion of the real whole arc of vibration to the length of the pendulum is I x 100/101 x 60.7 for pendulum 1821
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Manuscript details
 Author
 George Biddell Airy
 Reference
 PT/54/5
 Series
 PT
 Date
 1855
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Account of pendulum experiments undertaken in the Harton Colliery, for the purpose of determining the mean density of the earth, by G. B. Airy, 1855. From The Royal Society, PT/54/5
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