Making the Screw Thread Standard

[A] For most of the nineteenth century a screw and the nut that fitted it were made as a pair, and neither would serve for any other. [B] A workshop cut its threads on its own lathe, to its own angle and its own spacing, and a broken bolt was replaced by cutting a new one on the spot. Nothing about this was thought inefficient, because there was nowhere else the part could have come from. [C] Standardisation is usually described as the moment when somebody proposed a single system, and the proposals were in fact numerous and mostly ignored. [D]

What made one of them stick was not its merits. A national railway network needed repairs carried out at any point along a line by people who had never seen the machine before, and a company that had adopted a common thread could buy a bolt at a station instead of making one. Once the largest customers required a particular thread, workshops that wanted the business cut it, and the alternatives died without ever being refuted. This is worth remembering when a standard is defended on technical grounds. The surviving thread was a reasonable design among several reasonable designs, and what settled the matter was the purchasing power of an industry that could not wait.