The taming of the screw

by Paul Curzon, Queen Mary University of London

Image by Alexas_Fotos from Pixabay

Charles Babbage had an obsession for precision and high standards because if his machines were to work, they needed it. One of his indirect contributions to contraption construction the world over concerned the humble screw. We take screws pretty much for granted now, especially the idea that there are standard sizes. Lose one when putting together that flatpack furniture and you can easily get another that is identical. Before the 1800s though that was not the case. Screws made by different people were unlikely to be the same and might only fit the specific thing they were hand made for. Babbage’s demands for precision helped change that.

The key person in the invention of the standard screw was Stockport engineer, Sir Joseph Whitworth. Having worked as a boy in his uncle’s Derbyshire cotton mills, he was fascinated by the machinery there. He realised the accuracy of the workmanship in the machines was poor and needed to be better.

The Difference Engine was built by Joseph Clement in the years up to 1833, and who should be there helping him do so, having moved on to start a career as a skilled mechanic? None other than Whitworth. For Babbage’s machines to work they needed precision engineering of lots and lots of identical parts and to levels of accuracy far greater than previously needed. For the Difference Engine Clement and Whitworth, with their shared passion for accuracy, were up to the challenge. This work showed the coming need for ways to engineer ever more precisely, and to be able to repeat that work…a challenge Whitworth pursued for the rest of his life.

Also famous for inventing the first ever truly accurate “sniper rifle” he went on to create a standard thread for screws that then became the world’s first national screw thread standard: the British Standard Whitworth system. It suddenly meant screws could be made by mass production, bought from anywhere, and guaranteed to fit precisely for whatever job was needed. Whilst sadly the need to mass produce computers didn’t materialise, the standard was adopted for building ships, trains… for industry throughout the nation, making Great Britain’s industry more efficient and so more competitive. Now we rely on the idea of national and international standards like this not just for hardware but for software too. Standards help ensure our computers work but also keep us safe.

The equivalent of this engineering precision is still lacking in the development of software though, much of which is buggy and developed to poor standards by people hacking out software that may or may not work. High standards tend only to apply in safety-critical software, and then often poorly. We need the next generation of programmers to have the same obsession for precision of Babbage and Whitworth and apply it to the development of software, ending the age of buggy, poorly developed software.

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This article was funded by UKRI, through Professor Ursula Martin’s grant EP/K040251/2 and grant EP/W033615/1.

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