Foundations of metrology
In 1841 Whitworth was the first to establish a national thread standard which bears his name. Prior to this there were local standards within companies or pockets of industrial sectors but little which would lead to widespread interchangeability. His experience with threads led to the development of the highly accurate hexagonally rifled musket which is reputed to have allowed a Confederate sharpshooter to kill union General John Sedgwick from a range of over 1000 yards, just after he had famously proclaimed “they couldn’t hit an elephant at this distance”. Both Vernier and Whitworth were able to squeeze more accuracy out of contemporary measurement systems than their peers. I can’t help wondering what use they could make of modern measurement tools. n “I recall measuring the dimensions of our primary school playground with a rudimentary metre stick and being disappointed (or even affronted) at the relative inaccuracy of this.”
What impressed me then, more than the canapes and champagne, was the priority in 17th and 18th century France which was afforded to measurement machines and standards (there was a lot of brass and cast iron involved!) and which explains the impetus which Vernier had. This wasn’t just for scientific curiosities, but was baked into the very social fabric of the nation. There remains to this day two of an original 16 public marble metre standards from the time of the French revolution, embedded in the walls of a couple of otherwise innocuous buildings in the centre of Paris. Joseph Whitworth was the darling of later Victorian industrialisation on the manufacturing shop floor although with more direct impact on the toolroom than in the factory sweatshops and dark satanic mills of the period. He can be justifiably anointed the father of the “thou” by enabling a practical methodology of measurement for going beyond the traditional halving fractions of 1/32, 1/64, etc. of an inch
and later in the century managed to create a machine capable of measuring to a
millionth of an inch within a single linear dimension. This was basically a micrometer the size of a lathe.
Measurement & Manufacturing 15
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