After twelve months of carefully delving through archive boxes, inputting into spreadsheets, and importing data, the catalogue of the largest surviving collection of papers and letters of Henry Cavendish, 'the man who weighed the world', is complete.
In this short film, Project Archivist Erinna Cave, shares what we have discovered about Henry over this period (transcript below).
Henry Cavendish is one of the great scientists you may never have heard of. And perhaps that’s just the way he would have wanted it. His story is not only one of extraordinary discoveries but also one of isolation, eccentricity, and quiet devotion to science.
Born in 1731, Henry Cavendish grew up in an aristocratic family, but from an early age, life shaped him in ways that set him apart.
His mother, Lady Anne Cavendish, died when he was just two. This loss, and the absence of a maternal figure, marked him for life. Raised by his father, Lord Charles Cavendish, a fellow scientist, Henry was guided into a world of intellect without the warmth of a close maternal relationship.
He was a child who found comfort in solitude and numbers, a boy who preferred the companionship of books and experiments to the company of others. As he grew older, this quiet detachment would deepen. He rarely spoke unless spoken to and avoided large social gatherings. Yet, behind his reserved demeanour was a mind consumed by curiosity—an insatiable desire to understand the workings of the natural world.
Henry’s life was marked by discoveries that would shape the future of science. His experiments led to the discovery of hydrogen, which he referred to as "inflammable air."
He measured the density of the Earth with astonishing accuracy for his time and the instruments he was working with, and he was the first to reveal that water wasn’t an element, but a compound of hydrogen and oxygen.
These were ground breaking achievements, but Henry rarely published his findings. He seemed indifferent to recognition, content to leave his notes in private journals for others to find years later.
What makes Henry truly fascinating isn’t just the scope of his scientific work—it’s the contradictions in his personality. He could be intensely focused on his experiments, yet struggled with the simplest of social interactions. His household staff would often receive instructions through written notes, as he found face-to-face conversations too overwhelming.
However, Henry wasn’t completely withdrawn. He maintained a close relationship with his acquaintances, such as his relative, Duchess Georgiana, wife of the 5th Duke of Devonshire. Known for her vivacious social life, Georgiana found in Henry a kindred spirit for more intellectual pursuits. He was known to visit her at Devonshire House, where they would discuss the latest scientific matters, or her collection of minerals. These moments showed a softer, more personal side of Henry, who found comfort in familiar company and subjects of fascination.
But Henry’s eccentricity shone most vividly in his scientific experiments. He had a particular fascination with electricity, and delighted in proving that electric eels really could use electricity to shock you. He even built a device to mimic the effects of an electric eel, offering acquaintances at the Royal Society the chance to experience a mild electric shock themselves. Perhaps surprisingly, people were intrigued enough to accept this unusual invitation.
Despite his scientific accomplishments, Henry lived a life of quiet routine. He was a creature of habit, sticking to rigid schedules and conducting his experiments alone in his laboratory. His passion for understanding the world around him was unshakeable, yet he was unwilling to step into the limelight.
In fact, it was only decades after his death in 1810 that many of his works became widely known, thanks to his descendant, the 7th Duke of Devonshire, also a fellow scientist, who unearthed his papers and was determined to see them published.
Henry Cavendish's life offers us more than just a list of scientific triumphs. It is a testament to the power of quiet perseverance and intellectual curiosity. He lived for the quiet satisfaction of an excellently planned, accurate scientific experiment or the quiet contentment of working out a scientific theory.
Henry reminds us that behind every great mind is a complex human story—a story of solitude, eccentricity, and devotion to understanding the world in ways that most of us can only dream.
And perhaps that’s how he would have wanted to be remembered.
Henry's legacy
One of the most exciting developments to come from my work has been the inspiration that Henry Cavendish has provided to the team behind this year's Christmas at Chatsworth (2024), and to award-winning author, Joseph Coelho OBE, who has created an original festive story for Chatsworth with a young Henry Cavendish as the main protagonist; Henry and the Lion's Christmas Feast.
It has been wonderful to see how his life and works can illustrate, imagine, dream, write and create across a range of creative disciplines. I hope that as many people as possible will take the opportunity to see some of Henry's belongings from the collection on display in the house over the Christmas period.
Accessing the catalogue
You can view the catalogue of Henry Cavendish's letters and papers on the National Archive's Discovery pages here:
or on the Archives Hub here:
If you are unfamiliar with an archive collection, the more user-friendly site is Archives Hub.
An archival collection is structured from the top-down: the first information that you will view gives you an overview of the whole collection. The side-bar allows you to access information about various sections of the collection, and then downwards to more specific information about individual items.
Accessing Henry Cavendish's collection
Access to any items in the Henry Cavendish collection, or in any other archival collection held by the Devonshire Collections, is free to researchers, academics and students in our Collections Study Room, located in Chatsworth House.
The study room is open by pre-booked appointment only from Monday to Wednesday.
About Chatsworth House Trust
Chatsworth House Trust is the registered charity established to care for the house, collections, garden, and landscape for the benefit of everyone. All income from admissions, Gift Aid, membership, sponsorship, legacy gifting, and donations is reinvested in the essential conservation and improvement of Chatsworth, and in a programme of exhibitions, learning and community engagement.
Find out more about the charity and the many ways you can get involved here:
Film image credits:
Lady Anne Cavendish, Lady Rich (1612-1638) by after Sir Anthony Van Dyck (Antwerp 1599 - London 1641) ©National Trust Images
