But Lowell was the victim of an overactive imagination and mistranslation. A few years earlier in 1877, Italian astronomer Giovanni Schiaparelli had noted patterns on the surface of the red planet, which he called canali, or channels. Taking this to mean "canals", Lowell began to think they had been dug by a race of superhumans in a vain attempt to save their civilisation. Back on Earth, King Menes of Egypt had done something similar 6,000 years earlier, when he ordered the world's first major irrigation canal to be built. By the first century AD, the Romans had linked Arles with the Mediterranean, and artificial watercourses were well-established in China. The first locks, to control water flow and enable canals to climb gentle inclines, appeared in The Netherlands and Belgium around the 12th century.
In Britain, waterborne traffic grew as rivers were made navigable through the 16th century, and the first man-made waterway, the Exeter Ship Canal, opened in 1564. After the Duke of Bridgewater opened the first commercial canal, in Salford in 1760, canal mania ensued. Fortunes were made and lost as people sank their savings into puddled clay. Sensing competition, some railway companies bought canals then let them decline. Some, such as the short-lived Croydon canal in south London, were simply filled in and had a railway built on top. Gradually, these conduits of the Industrial Revolution went quiet as freight traffic transferred to roads. The opening in 1894 of the Manchester Ship Canal (celebrated in the children's rhyme "The Big Ship Sails on the Alley Alley-O") revived seagoing canal traffic, and the Suez and Panama canals traversed land masses to link neighbouring seas.
Nationalised in 1947, the 2,000 miles, 5,000 bridges, 400 aqueducts and 60 tunnels of Britain's inland waterways then fell into disrepair, only for their leisurely pace to prove their salvation. Nowadays, this irregular grid of straight-sided ditches that covers the country is home to a floating population of holidaymakers going nowhere, slowly. Now what would the Martians make of that?