Measure for measure

It began with a letter in London's Daily Telegraph. A Mr Geoff Smith from Carlisle was relating how he'd been working on the installation of two underwater pipelines “185km long and 28in and 30in diameter. Each section of pipe is 18ft long and the skin thickness was 7mm protected by 3-4in on concrete.” He went on to say that none of the people from the 15 nations involved had a problem in being bilingual in the various measurements. How do we come to have such a muddle of measurements?
We sent Chris Morrissey off to investigate.

They say that the size of America's space shuttle was determined by the width of a horse's rump. As the story goes, there is a direct connection between the wheel spacing of the Roman army's two horse chariot, the standard gauge of US railroads, and the size limit for rocket components that have to be moved by rail. Moonshine or not, there are some strange chains of cause and effect in the wacky world of weights and measures.

Every civilization has had its own way of measuring, creating thousands of units that have mostly passed into history. Some survive locally as living fossils, and some have been redefined or renamed for modern use. Many of today's units are new inventions, made necessary by the march of science.