Project Archivist Erinna Cave shares her latest discoveries from the papers of scientist Henry Cavendish, revealing details of his further interests and friendships.

While Henry is undoubtedly very shy and reserved, it is time to examine his personal life in a little more detail. He did live a secluded life, yet it was still a life that saw him playing an active role in several public organisations, while carefully managing his inherited family estates and wealth, and socialising with his limited circle of friends. 

Memberships

Looking at his role in public organisations, he was a trustee for the British Museum (founded 1753) and one of the founding proprietor of the Royal Institution, an organisation established to introduce new technologies and science to the general public.

He was an extremely diligent member of the Royal Society, serving on at least twenty-three committees covering subjects such as reviewing scientific papers, securing gunpowder stores from lightning strikes, planning expeditions to observe the transit of Venus, sponsoring exploration of the Northwest Passage, and supervising the scientific instruments in place at Somerset House (the home of the Royal Society). For his work on these committees, he connected with many other leading scientists including Benjamin Franklin, Joseph Banks, Joseph Black, William Herschel and others in France, Germany and Sweden. 

Property development

Henry inherited estates in Nottinghamshire and Derbyshire from his father along with substantial wealth from his father’s cousin Elizabeth.

We hold hundreds of letters of correspondence between Henry and his land stewards. These show Henry’s active management in these estates, and his opinion on topics such as rents arrears and church repairs.

Henry also developed land on Clapham Common, West London. At the end of the 18th century, Clapham Common was communal open land criss-crossed by footpaths used for grazing and collecting firewood by villagers from Clapham and Battersea. In the 1790s the land was sold to individuals triggering a boom in villa building.

Henry joined in this development by purchasing 15 acres and leasing it to builders Hanscomb & Fothergill, in association with Thomas Poynder (an eminent City bricklayer). They agreed to spend £10,000 over eight years in building “good and substantial dwelling houses with convenient stables coach houses”.

Between 1791-1806, six houses were duly built and leased to tenants. They were all sold at auction by the 6th Duke of Devonshire in 1827. Only one of these houses survives today: 21 Clapham Common West Side (Heathfield), which last sold for £9.25m: certainly a "good and substantial" house. 

Friends and acquaintances

As to Henry’s social acquaintances, there is good evidence that he spent time with Georgiana, Duchess of Devonshire, and visited her at Devonshire House.

Georgiana had become interested in the natural sciences during her time in continental Europe in 1792-1793. She developed into an amateur chemist and mineralogist, amassing a collection of minerals still extant in the Devonshire Collections.

Her knowledge was sufficiently extensive for her mother to write that Georgiana had “really a genius for it. Padres Patrini one of the first men in that line in Italy, & Sir Charles Blagden here have both assured me […] that the degree of knowledge the Dss has acquired & her observations were very extraordinary. Mr Cavendish too I find is delighted with her. He calls upon her frequently & if he has anything to communicate to the Duke, he always comes to [visit] her, to tell him such &such things from him.”(i)

This is a curious hint that Henry perhaps found it easier to speak with Georgiana, rather than his own relative the 5^th Duke. Imagine the scene of Henry, who wore the same style of clothing all his life, sitting beside Georgiana, the icon of fashion, in the sumptuous surroundings of Devonshire House.

The abovementioned Sir Charles Blagden was the secretary of the Royal Society, Henry’s personal secretary and friend, who had befriended Georgiana in Switzerland.

His diaries, held at the Royal Society, show Henry visiting Devonshire House and accompanying Blagden to the Royal Society Club. They offer tantalising scraps of Henry’s personality “Next to club: pleasant and C better than usual”, “showed Mr Cavendish the drawings of [?] paper on Venus […] he seemed more than usually jealous”, and “agreed that [Henry Cavendish] had no affections, but always meant well”(ii).

Henry certainly meant well in his will. He left legacies to his friends Blagden and Alexander Dalrymple, and to all his servants. He also paid a pension to his librarian Charles Heydinger’s widow for years after Heydinger’s death, until his own death in 1810.

From these fragments of Henry’s personal life, hopefully a fuller picture of his life, once characterised as “only a cold, clear intelligence, raying down pure white light, which brightened everything on which it fell but warmed nothing”, can be appreciated. 

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Chatsworth holds an extensive archive that includes the personal papers of the Devonshire family, historically significant acquisitions, and estate and staff records.

The Chatsworth House Trust charity (registered charity 511149) funds the preservation, restoration and cataloguing of these papers, sharing the findings to advance our understanding of historical figures, events and places, and to make them available to anyone conducting research for academic or personal reasons.