Cavendish, Henry 1731 - 1810

Henry Cavendish was born on 10 October 1731, the third son of Lord Charles Cavendish, the duke of Devonshire. He went to the Hackney Academy and entered Peterhouse College in Cambridge in 1748. He remained at Cambridge for three years, before moving to live with his father in London, where he soon had his own laboratory. His father lived a life of service, first in politics and increasingly in science, especially in the Royal Society of London. In 1760 Henry Cavendish was elected to the Royal Society and he was active in a number other academic instittuions, including the British Museum. Soon after the Royal Instittuion of Great Britain was established, Cavendish became a manager and took an active interest, especially in the laboratory, where he observed and helped in Humphry Davy’s experiments.

Cavendish was a shy man who was uncomfortable in society and avoided it when he could. He did however produce notable research in the natural sciences. He is perhaps best known for his discovery of hydrogen, which he termed ‘inflammable air’ and which he discussed in his first published paper ‘On Factitious Airs’ in 1766. His name is also associated with the Cavendish experiment, which he performed between 1797 and 1798 and which was the first experiment measuring the Earth’s density, and therefore its mass. The figure for the density of the Earth obtained by Cavendish is within 1% of the currently accepted figure. The experiment also proved that Newton’s law of gravitation worked on much smaller scales than those of the solar system.

Cavendish also worked out a comprehensive theory of electricity which he published in 1771. However, the bulk of his electrical experiments did not become known until they were collected and published by James Clerk Maxwell in 1879, long after other scientists had been credited with the same results. Cavendish's electrical papers from the Philosophical Transactions of the Royal Society of London have been reprinted, together with most of his electrical manuscripts, in The Scientific Papers of the Honourable Henry Cavendish, F.R.S. According to the 1911 edition of Encyclopædia Britannica, among Cavendish's discoveries were the concept of electric potential (which he called the ‘degree of electrification), an early unit of capacitance (of a sphere one inch in diameter), the formula for the capacitance of a plate capacitor, the concept of the dielectric constant of a material, the relationship between electric potential and current (now called Ohm's Law) (1781), laws for the division of current in parallel circuits (now attributed to Charles Wheatstone), and the inverse square law of variation of electric force with distance, now called Coulomb's Law.

Cavendish died in Clapham on 24 February 1810 and was buried, along with many of his ancestors, in the church that is now Derby Cathedral.