It was built at unprecedented speed to exhibit the globe’s greatest treasures and manufacturing achievements to the world. Now, the mystery of how the Victorians managed to erect the Crystal Palace so quickly in 1851 has finally been solved. Experts have discovered that the answer to this 173-year-old riddle lies in the first known use of standardised nuts and bolts in construction – a humble engineering innovation that would power the British empire and revolutionise the industrial world. Measuring a colossal 92,000 sq metres, the groundbreaking iron and glass structure of the Crystal Palace was built in just 190 days to house the 14,000 exhibitors taking part in the Great Exhibition of the Works of Industry of All Nations, in Hyde Park, London. Newly analysed evidence suggests the pioneering building could not have been built without cutting-edge Victorian technology: interchangeable nuts and bolts that were made on machines to match one standardised size across the industry. Prior to this, skilled craftsmen would typically make each individual nut and bolt bespoke and ensure they fitted together. Since no two screws were necessarily alike, it was almost impossible to replace one that got lost or broken, causing “endless trouble” for contemporary engineers and ensuring big construction projects relied primarily on bricks and mortar. Prof John Gardner, of Anglia Ruskin University, said: “The Crystal Palace was the biggest building ever constructed in Britain, at that time. It had to be built cheaply and it had to be built in 190 days – which is still pretty quick even today.” In the 1850s, such speed was “remarkable”, he said. “It was unprecedented and my question was: how on earth did they manage it?” Approximately 30,000 nuts and bolts connected the 3,300 cast-iron columns of the palace, which was relocated to south London in 1852 and destroyed in a fire in 1936. “It was a brand-new departure from traditional materials and methods. They only used wedges and screws to hold the thing together.” Constructing a building like this seemed an “impossible” feat to him, if every nut had to be mated to a specific, individual bolt. “You couldn’t have that kind of system and create a building like that with 30,000 nuts and bolts.” Gardner approached the Crystal Palace Museum, which houses the remnants of the building, to get hold of some of the original nuts and bolts and analyse them. His request took the curator, Ken Kiss, by surprise. “They were in the collection but nobody had ever asked to look at them before,” Gardner said. Gardner measured the screws and fasteners he was sent and discovered they were all standardised nuts and bolts. “They were using a standard that had been suggested by Joseph Whitworth 10 years before, in 1841, but wasn’t adopted as a British standard until 1905. That was an absolutely groundbreaking decision by Fox Henderson [the construction firm that built the palace], because it meant you could have a nut made in one workshop and a bolt made in another – and they could fit together.” The Great Exhibition showcased innovative British machines and inventions, along with unique cultural artefacts from Britain’s colonies, and was attended by 6 million people, including Charlotte Brontë, Charles Darwin and Lewis Carroll. After interchangeable nuts and bolts were used so successfully to speedily construct the Crystal Palace, demand for standardised threading grew. More workshops began to adopt the Whitworth standard and it was quickly picked up by factories. Soon, engineers began using interchangeable nuts and bolts that met the standard to mass-produce steam engines for trains and for gunboats in the Crimean war. “It becomes possible to build things more efficiently, more cheaply and more quickly – and the construction of Crystal Palace showed that, right at the beginning,” Gardner said. The practice may even have given the British a military edge, he suggested. “It certainly helps if you can make your weapons quickly.” This article was amended on 16 September 2024. The Great Exhibition included items from many parts of the world, not just the British empire as an earlier version said.