Despite his fame as a scientist, Henry Cavendish was painfully uncomfortable in social situations.
One early biographer described him as "shy and bashful to a degree bordering on disease. He could not bear to have any person introduced to him, or to be pointed out in any way as a remarkable man". In one memorable meeting at the home of Sir Joseph Banks, he was introduced to an Austrian admirer of his work. The visitor told Cavendish that he had specifically come to London to meet him and spoke at length on Cavendish's accomplishments and how he was one of the great scientists of his time. In reply, Cavendish "answered not a word but stood with his eyes cast down, quite abashed and confounded. At last spying an opening in the crowd, he darted through with all the speed of which he was master, nor did he stop until he reached his carriage which drove him directly home". This was typical behaviour for the great scientist whose social awkwardness was legendary.
Throughout his lifetime, there were numerous anecdotes about Cavendish's solitary nature and his eccentric behaviour. Often described as afraid of strangers (especially of the female variety), he mainly communicated with the female servants in his household through written notes and even had a back staircase built onto his house to avoid having to face his housekeeper. Many of his fellow scientists commented on his thin, shrill voice which often trailed off whenever he was uncomfortable or embarrassed (as he frequently was). According to Sir Humphrey Davy, "his voice was squeaking, his manner nervous, he was afraid of strangers and seemed, when embarrassed, to articulate with difficulty. He wore the costume of our grandfathers; was enormously rich, but made no use of his wealth". Although Cavendish was a distinguished member of the Royal Society, he only attended club dinners and never saw visitors in his own home. Even at those dinners, he was notorious for his shyness and was often seen loitering outside the room where the other guests were gathered, working up the courage to face them. Not surprisingly, he never married and, much like his fellow eccentrics Isaac Newton and Nikola Tesla, may well have died a virgin.
Henry Cavendish was always seen as eccentric, even as a child. Born in Nice, France in 1731, the Cavendish family traced its lineage back more than 800 years and both his parents were titled aristocrats. He was probably the highest-born of all the English intellectuals (only Robert Boyle came close), a far cry from the usual middle-class background of most other scientists. His mother had longstanding health problems and died when he was two years old. It was through his father, Lord Charles Cavendish, a gifted experimental physicist in his own right that Henry Cavendish was first introduced to scientific research. Little is known about his early childhood except that he eventually attended St. Peter's College in Cambridge but left before completing his studies there. For the next ten years after his leaving Cambridge in 1753, no record exists although he later joined the Royal Society in 1760 and published his first scientific paper in 1766. From that point on, the sheer scope of his scientific writing was phenomenal.
Along with his revolutionary research in chemistry, Cavendish also did groundbreaking work in mathematics, electricity, astronomy, meteorology, and geology, (to name just a few of the fields that aroused his scientific curiosity during his long life). He was an advocate of the phlogiston theory of combustion until Lavoisier's experiments led him to reconsider his earlier views. He apparently disliked the new direction that chemistry was taking based on Lavoisier's findings and, after publishing his own groundbreaking research in 1788, devoted himself to research in other fields instead. Cavendish's switch to other areas of science was probably due to the great "Water Controversy" over whether Cavendish, James Watt or Antoine Lavoisier should be credited with the discovery of the chemical composition of water.
While Cavendish was likely the first to carry out experiments separating water into "phlogisted" and "unphlogisted" components, it was Lavoisier who probably deserves the credit for realizing the implications of Cavendish's findings. In an uncharacteristic move however, Cavendish publicly accused Lavoisier and Watt of "treating him unfairly" and the controversy dragged on for years. Whether this had anything to do with his decision to give up his chemistry research is an open question. Cavendish is also famous for designing the first experiment to measure the force of gravity between masses under controlled conditions (a.k.a. the Cavendish experiment) as well as developing some of the standard chemical apparatus still used in laboratories today.
Aside from what little he revealed in his writings and the occasional stories by the scientists who were his only friends, Henry Cavendish's personal life remains a mystery. He spent most of his life in poverty due to his father's refusal to give him more than a tiny pension for his support, According to one biographer, "During his father's lifetime, he was kept in rather narrow circumstances, being allowed an annuity of [500 pounds U.K] only, while his apartments were a set of stables fitted up for his accommodation. It was during this period that he acquired those habits of economy and those singular oddities of character that he exhibited ever after in so striking a manner". Although he regularly attended the Royal Society dinners, he never had more than five shillings in his pocket to pay for the dinner (his father only gave him that amount to pay for the dinner and nothing more).
Despite a late-life inheritance which made Cavendish one of the wealthiest men in England, there was little outward change in his extremely modest lifestyle. While he established a town residence near the British Museum, the very few visitors that he received there reported that "books and apparatus formed its chief furniture". He also set up a separate house in Soho which he operated as a lending library for the many books he possessed. His elaborate system of receipts to keep track of the books lent out (even the ones he took for his own use) proved unworkable and he eventually hired a German scholar to act as librarian.
Henry Cavendish's favourite residence was in Clapham Commons (one of the streets there still bears his name). Although the house was certainly enormous, only a small set of rooms were for his personal use. All the rest was turned into laboratory and workshop space for Cavendish's numerous experiments. His hobby of collecting fine furniture seemed to be his only extravagance. The very few guests there commented on Cavendish's penny-pinching habits, "if anyone dined with Cavendish, he invariably gave them a leg of mutton, and nothing else". According to another story about Cavendish, when he entertained a group of four scientists and the housekeeper commented that the usual leg of mutton wouldn't be enough. His answer? "Well then, get two".
Henry Cavendish died on February 24, 1810 at the age of seventy-eight. He was buried at the Cathedral of All Saints in Derby, England in the family mausoleum. The full extent of his scientific genius became clear in the late 19th century when James Clerk Maxwell, in reviewing many of Cavendish's papers, found extensive notes on scientific experiments that Cavendish had carried out without ever sharing his results with fellow scientists. The experiments anticipated many scientific discoveries made decades after his death for which other scientists received the credit. Why Cavenedish failed to publish these results is just one of the lingering mysteries surrounding his strange scientific career.
Did Henry Cavendish suffer from Asperger's Syndrome? Oliver Sacks, along with other modern clinicians, have cited Cavendish's social anxiety, routine-bound repetitive behaviour, and obsessional nature (at least as far as science was concerned) as evidence for autistic symptoms. Unfortunately, there is little information regarding his childhood but later descriptions of his solitary nature, emotional remoteness, odd gait, panic attacks, and tendency to engage in compulsive routines seem to bear out the diagnosis. Whatever the reason for his oddly reclusive nature, Henry Cavendish continues to be remembered as arguably the greatest English scientist of all time after Isaac Newton. Whether the pathology he showed in life kept him from achieving even more than he did is a question that can't be answered.