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32 Cavendish's residences were in Gower Street and Dean Street, Soho, but his favourite home was Cavendish House, Clapham. In the last-mentioned residence (which was demolished in 1905) most of the rooms were converted into laboratories, workshops, and observatories. The author visited Cavendish House and grounds on 9th August 1905, and took several photographs. The house was situated on the south side of Clapham Common, and within its walls one of the most remarkable feats of science was accomplished. Just under the vane (centre window of the second storey) was a small room in which Cavendish weighed the earth.

In 1798 he computed its mean density by comparing the force of terrestrial attraction with that of the attraction of something of known magnitude and density. This done, an approximation of the weight of the earth became possible. The mean of twenty-three experiments was that the earth weighed 5·45 times that of a globe of water of equal size—the accepted figure now being 5·50. This and a vast amount of work was performed within the walls of Cavendish House, which stood in nine acres of beautifully timbered land; and here one of England's greatest chemists "buried his science and his wealth in solitude."

It was in this house that exact quantitative work on electricity received a great impetus by the researches of Cavendish. In 1771 he published important