The
Cavendish experiment, performed in 1797–1798 by British scientist
Henry Cavendish, was the first experiment to measure the force of
gravity between
masses in the laboratory and the first to yield accurate values for the
gravitational constant. Because of the unit conventions then in use, the gravitational constant does not appear explicitly in Cavendish's work. Instead, the result was originally expressed as the
specific gravity of the Earth, or equivalently the mass of the Earth. His experiment gave the first accurate values for these geophysical constants. The experiment was devised sometime before 1783 by geologist
John Michell, who constructed a
torsion balance apparatus for it. However, Michell died in 1793 without completing the work. After his death the apparatus passed to
Francis John Hyde Wollaston and then to Henry Cavendish, who rebuilt the apparatus but kept close to Michell's original plan. Cavendish then carried out a series of measurements with the equipment and reported his results in the
Philosophical Transactions of the Royal Society in 1798.