How Standard Screws Solved a 173-Year-Old Architectural Mystery

Historians and researchers have finally solved a long-standing mystery behind one of Victorian England’s iconic architectural wonders. The answer? Simple, standardized nuts and bolts. That may not sound exciting today, but in 1851, the invention allowed engineers to build the Crystal Palace at previously unimaginable speeds.

While the Great Exhibition of 1851 showcased Britain’s most advanced and acclaimed industrial capabilities in a series of displays, the crown jewel of the five-month event undoubtedly came from architect Joseph Paxton. At over 1,827 feet long, the Crystal Palace was the largest building in the world at the time and featured a vast glass roof supported by 3,300 cast-iron columns. For nearly 175 years, however, one mystery has puzzled historians: how were Paxton’s workers able to complete its construction in just 190 days?

A study published in The international journal for the history of technology and engineering has now solved the mystery. According to John Gardner, a professor of English literature at Anglia Ruskin University (ARU), the Crystal Palace relied on a revolutionary screw thread designed by a man named Joseph Whitmore.

Before Whitworth’s standardized concept, every screw and bolt was unique to each other with no standardized measurements. This meant that lost screws or broken bolts could easily bring construction projects to a halt, at least until someone made new replacements. Given its immense size and complexity, the Crystal Palace alone required 30,000 nuts and bolts, and yet somehow the fact that so many parts were needed didn’t hinder the building’s construction in any way.

“The forms of screw thread used in Crystal Palace buildings are not recorded in any of the surviving drawings,” Gardner and his co-author Ken Kiss wrote in their paper. “Furthermore, none of the rare extant bolt threads have been measured, recorded and published, until (now).”

The reason for the original bolts’ rarity is that the Crystal Palace burned down in 1936 after its deconstruction in Hyde Park and subsequent rebuilding in south London in 1854. But Kiss, curator of the Crystal Palace Museum, unearthed one of the last known bolts from a column at the building’s original site, as well as a nearby water tower that had been built at the time to power the palace’s fountains. Kiss then gave these archaeological artifacts to Gardner for analysis.

Gardner discovered that the Crystal Palace column bolt exactly matched Whitworth’s measurements, years before it became known as the British Standard Whitworth (BSW), the world’s first national specification of its kind. After soaking the water tower nut and bolt in oil and then using a combination of heat, force and hammering, he also discovered measurable threads that also matched the BSW specifications. To further prove his theory, Gardner manufactured completely new bolts with BSW threads that perfectly matched the original nut.

According to the study’s co-authors, adopting Whitworth’s new, standardized option allowed builders to complete the monumental undertaking in a relatively short time. The results were ultimately seen by some six million visitors to the Great Exhibition between May and October 1851. But as to why such a detail was overlooked for decades, Gardner pointed to the pace of revolutionary technological change at the time.

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“During the Victorian era, there was incredible innovation from workshops across Britain that helped change the world,” Gardner said in an accompanying statement. “In fact, progress happened so quickly that some breakthroughs may never have been realized at the time, as was the case with the Crystal Palace.”

Like the Crystal Palace itself, the exact BSW specifications are not often used today, but their legacy has influenced a number of modern variations that do not stray too far from the original measurements. Similarly, the Crystal Palace, though long gone now, has inspired modern architecture for decades.