A volcano erased the summer of 1816 and the bicycle was born

Mount Tambora, on the Indonesian island of Sumbawa, blew on 10 April 1815 and cooled the planet by almost a degree: the following year there was no summer in Europe or North America. It snowed in June in New England, and the grain harvest failed from Ireland to Hungary. Two years later, a German forestry official walked out into the street with the first machine ever built with two wheels in line.

There is an animal between those two facts. When the grain went, the oats went with it, and oats were the fuel of transport: prices soared, and across central Europe horses were slaughtered because there was nothing left to feed them. Karl Drais, an official of the Grand Duchy of Baden, had spent years looking for a way to travel without depending on them. On 12 June 1817 he set off from Mannheim on a wooden frame weighing twenty-two kilos, with no pedals and no brakes, pushed along by his feet against the ground. He covered some fourteen kilometres in a little over an hour: four times what walking would have taken.

He called it the Laufmaschine, the running machine. Drais never wrote down that he had invented it because of the dead horses; that connection was reconstructed in the 1990s by the historian Hans-Erhard Lessing, who matched the dates of the famine against the dates of Drais's workshop, and it is the accepted explanation today. Drais registered his privilege on 12 January 1818 and died penniless in 1851, thirty-four years before another manufacturer fitted a machine like his with a chain and pedals.