Boys' experiment to determine G

A mounted set of photographs illustrating measurements made on the apparatus used in the cellars of the old Clarendon Laboratory by C.V.Boys in 1895 to measure the gravitational constant G, was discovered in the Clarendon in 1990. The photographs themselves were largely undamaged but the mounting cardboard had become very brittle and was disintegrating. In particular the caption for photograph 7 was missing.

Boys states in his paper that he intended "to leave also permanently in the [Science] Museum a series of photographs of the apparatus as it appears in situ when each of the [measuring] operations is being carried out". It seems likely that the photographs in the Clarendon Archive are these photographs. They do not appear in Boys' paper and the Science Museum do not have copies. They do not show the torsion beam or the inner construction of the apparatus. For this you should refer to Boys' original paper Philosophical Transactions of the Royal Society, 186, 1, (1895).

The Physics Photographic Unit scanned the original photographs and digitally removed any damage. They were then saved as compressed jpg image files using a compression factor of 200. The average size is 10.5KBytes; the largest is 14KBytes.

Background to the experiment

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