Chatsworth stands in a wide green valley in the Peak District of Derbyshire, beside the River Derwent, with wooded hills rising behind it and a great cascade of water down the slope beside the house. It is one of the very few great houses still lived in by the family that built it, over four hundred and fifty years and sixteen generations of the same line.

Bess of Hardwick

The story begins with Bess of Hardwick, the same woman whose other great house we visited yesterday. Bess rose through four marriages to become the richest woman in England after the Queen. Her second husband was Sir William Cavendish, and every Duke of Devonshire since descends from the two of them. She is the root of the family.

Bess and Sir William bought the estate in 1549 and began building in 1553. Sir William had made his fortune as one of Henry VIII’s officials during the dissolution of the monasteries, and Bess persuaded him to sell his lands in Suffolk and settle in her native Derbyshire. He died before the house was finished, and Bess completed it in the 1560s. Only later, after her fourth marriage collapsed, did she go back to her birthplace and build Hardwick. Her Chatsworth was an Elizabethan house around a courtyard, and it was here, in rooms still called the Queen of Scots apartments, that Mary, Queen of Scots was held prisoner on and off for years, in the custody of Bess and her fourth husband.

At Chatsworth, Bess is barely present. The house Bess built was almost entirely pulled down and rebuilt between 1687 and 1707, so almost nothing you walk through today is hers. At Hardwick it is the opposite. Her house there survived nearly untouched, her initials carved along the roofline, her tapestries still on the walls. We only caught it because we saw them a day apart. This is the sort of thing we go looking for on the road, a fact that hides in one place and shouts in the next.

The Cavendishes

The house passed down Bess’s Cavendish descendants, who rose in rank over the generations. Her son became the first Earl of Devonshire. A century later, the fourth Earl helped put William of Orange on the English throne in the revolution of 1688, and for that service was made the first Duke of Devonshire in 1694. It was this first Duke who turned Bess’s Elizabethan house into the Baroque palace of golden stone we see now, rebuilding it front by front, with a great painted hall and state apartments. His architect was William Talman, though the Duke, who loved building, kept a strong hand in it himself.

Later dukes added rather than replaced. The sixth Duke, in the early nineteenth century, built the long north wing and laid out much of the garden, helped by his gardener Joseph Paxton, who went on to design the Crystal Palace in London. The house you walk through is the work of many generations, each leaving its mark, all of them Cavendishes.

The family still lives here, though not in the grand rooms you tour. They keep private apartments in the house, off the public route, while the state rooms are opened to visitors. Since 1981 Chatsworth has been held by an independent charity, the Chatsworth House Trust, which cares for it on the family’s behalf.

The scientist in the family

The Cavendishes produced one scientist of the first rank. Henry Cavendish, born in 1731, was a grandson of the second Duke, from a younger branch outside the line of succession, which left him free to spend his life on science. He discovered hydrogen and showed that water is a compound rather than an element. In his most famous work, the “Cavendish experiment,” he measured the gravitational constant, the number that fixes the strength of gravity throughout the universe, and from it worked out the mass of the Earth. His value was so exact it was barely bettered for a century, and the modern figure sits remarkably close to his. His papers and instruments are kept at Chatsworth.

The name reaches forward to a place we have already stood. The Cavendish Laboratory in Cambridge, where the electron was found and the structure of DNA worked out, was named for this same family. A private scientist in a Derbyshire family, a house full of his papers, and a world-famous laboratory three counties away, all one name. This is what we love to learn.

The library

Chatsworth holds one of the richest private collections of art and books anywhere. The dukes collected across five centuries, and the house is full of Old Master paintings, drawings by Rembrandt and Leonardo and Raphael, sculpture, furniture, silver, and porcelain.

The library is the heart of it. The sixth Duke turned the old Long Gallery into a library for his books, and today over seventeen thousand volumes stand there, spanning six centuries. It has been called the finest private library in the world. It holds the manuscripts of Thomas Hobbes, the philosopher who wrote Leviathan and served for a time as tutor and secretary to the family, so his handwritten papers came to rest here. The scientific manuscripts of Henry Cavendish are here, each stamped with his name. There is a first edition of Copernicus, the book that placed the Sun at the centre of the heavens, and the first printed atlas of England, alongside illuminated medieval manuscripts. The sixth Duke built much of it by buying four entire libraries at once.

For four and a half centuries one family had the wealth, the continuity, and the interest to gather things and keep them, and because they never sold up and never left, the collection stayed together in the house it was made for. Most such collections were broken up and scattered long ago.

Visiting

Chatsworth is a full day. The state rooms, the painted hall, the library, the sculpture gallery, and the collections need time, and so do the grounds: the great Cascade, the Emperor Fountain, the maze, and over a hundred acres of garden in a park landscaped in the eighteenth century.