The steam engine

technology · earth · Britain

Treated here as one technology across its whole eighteenth-century development, because what mattered economically was a sequence of changes to a single machine rather than a single invention. Newcomen's atmospheric engine (1712) made mine drainage possible at any efficiency. James Watt's separate condenser, patented in 1769, kept the working cylinder permanently hot by condensing the steam in a separate vessel, and cut coal consumption per unit of work by something on the order of two-thirds to three-quarters — which mattered enormously away from the pithead, where coal had to be bought and carted. Rotative engines from the early 1780s, using the sun-and-planet gear, converted reciprocating motion into a turning shaft, and that is the change which let steam drive a mill rather than only a pump. The consequence that reorganised the map came last and is often stated backwards: steam did not make power cheaper than water — good water sites remained cheaper for decades — it made power PORTABLE. A watermill must be where the fall is; a steam mill can be wherever coal can be delivered, which meant a town, which meant labour, credit, finishing trades and a canal wharf in the same place.