Henry Cavendish

Henry Cavendish

The man who weighed the world

If you are interested in Science and History, then a trip to Chatsworth House in Derbyshire is well worth a visit. The Cavendish family has owned the house since 1552 when Sir William Cavendish first purchased the manor.

The most notable member of this fine family was the scientist Henry Cavendish Grandson of the second Duke William Cavendish. Henry was born in Nice France in 1731 his mother was Lady Anne Grey, and his father was Lord Charles Cavendish. Charles Cavendish himself was an able politician and scientist who received the Royal Society Gold Medal for inventing the maximum and minimum thermometer.

Sadly Henrys mother died when he was only 11years old, his father never remarried so Henry lived with his father and brother in Clapham, where he used to help out with his fathers experiments. He was educated at Dr Newcombes School in Hackney and at the age of 18 went to Cambridge to study at St Peters Collage now known as Peterhouse. However he did not graduate from University and left after four years returning to his father’s house in Great Marlborough Street to continue his scientific work along side his father. His first paper, “Factitious Air’ was published 1766. In this paper he described the properties of “Inflammable Air” as he called it and how it formed water on combustion. Antoine Lavoisier reproduced these experiments at a later date and gave the element its name Hydrogen. Cavendish later went on to accurately describe the composition of the Earth’s atmosphere.

Cavendish was a painfully shy man and was said to avoid having to speak to his household staff he would enter and leave his house through a back staircase that he had specially built. Because of his shyness and unassuming manner, he often avoided publishing his work. It was not until many years after his death, that James Clerk Maxwell looked through his papers and found that many of his discoveries had been attributed to others. Such as, Richter’s Law of Reciprocal Proportions, Ohms Law, Dalton’s Law of Partial Pressures.
However Cavendish did have a few friends in the Royal Society to which he allowed free access to his magnificent library in Soho Square, London – four miles from his residence so that he might not encounter persons coming to consult it.

Perhaps his greatest achievement was correctly calculating the density of the Earth. The apparatus used was actually designed by John Michell a famous geologist of the time. However Michell died before he could begin the experiment. The apparatus was sent in crates to Cavendish, who completed the experiment in 1797. The apparatus consisted of a torsion balance to measure the gravitational attraction between two 350-pound lead spheres. Many years later his results were reinterpreted to calculate the constant G, and the mass of the Earth, best modern estimates put this at 5.9725 billion trillion tonnes. This is only 1% out from Cavendish’s calculations.

Cavendish died in 1810 at the age of seventy nine, he left a very large estate which was later used by his relatives to endow the Cavendish laboratory at Cambridge in 1871. Cavendish’s beautiful library and some of his scientific Henry instruments went to Chatsworth House and are still there today.

The final word should be left with the sixth Duke of Devonshire, William Spencer George Cavendish (1790 1858 ) he wrote:- ” That philosopher,the man who weighed the world and buried his science and his wealth in solitude and insignificance at Clapham.