In November 1827, some fifty guests in evening dress sat down to a banquet in a candlelit hall draped with crimson — beneath the bed of the Thames. The band of the Coldstream Guards played, toasts were drunk, and in the neighbouring archway more than a hundred of the project's miners dined at their own long tables. The host was a 21-year-old engineer named Isambard Kingdom Brunel, and the dinner was a publicity masterstroke: proof, staged with theatrical nerve, that a tunnel the river had flooded six months earlier was now safe enough to eat in. It was not, quite. Within two months the Thames would break in again and very nearly kill him.
Nobody had ever driven a tunnel beneath a navigable river. The Cornish engine pioneer Richard Trevithick had tried under the Thames in 1807, and his small pilot tunnel flooded close to the far shore before the scheme was abandoned. The riverbed here was not honest rock but treacherous gravel, silt and sand. The solution came from Isambard's father, Marc Brunel, a royalist émigré who had fled revolutionary France. Marc had studied the shipworm Teredo navalis — the mollusc that bores through ships' timbers, lining its burrow with a smooth shell as it goes — and in 1818 he patented a machine that worked the same way: the tunnelling shield. It was a great iron honeycomb of thirty-six cells, each holding a miner who excavated a few inches at a time behind removable boards, while bricklayers walled up the tunnel close behind, so the ground was never left unsupported. Every tunnel-boring machine on Earth is that worm's descendant.
Work began at Rotherhithe in 1825, with the access shaft sunk by an ingenious trick: a heavy brick tower was built on the surface and allowed to slice down into the ground under its own weight. Marc's son Isambard, aged about twenty, became resident engineer. Conditions were vile. The Thames was effectively an open sewer, so the water seeping through the roof was foul; pockets of gas flared into flame at the miners' lamps, and men were carried out sick and half-blinded, the young Brunel among them.
Floods, fame and the Great Bore
The river broke through in May 1827, filling the works. Isambard descended to the riverbed in a diving bell to inspect the hole, had bags of clay dumped into it, pumped the tunnel dry — and threw the famous banquet. In January 1828 the Thames burst in again, this time drowning six men; Isambard, badly injured, was dragged from the water and sent away to recuperate — it was while convalescing near Bristol that he entered the competition to design the Clifton Suspension Bridge. Then the money ran out. The tunnel face was bricked up, and for seven years the half-finished work stood idle, mocked in the press as "the Great Bore".
A Treasury loan revived the project in 1835, and after nearly two decades of labour the Thames Tunnel finally opened on 25 March 1843, running from Rotherhithe to Wapping — the first tunnel ever completed beneath a navigable river. Pedestrians paid a penny to walk through, and they came in astonishing numbers: roughly a million people passed through within months of opening. Queen Victoria and Prince Albert paid a visit. Souvenir stalls filled the archways, and the tunnel hosted fancy fairs and concerts under the river; admirers called it the Eighth Wonder of the World. Yet as a business it failed. The grand spiral ramps that would have let horse-drawn cargo use the tunnel were never built — there was no money left — so the great highway under the Thames earned pennies from foot traffic, and once the novelty faded it acquired a reputation as a damp haunt of pickpockets.
Salvation came from a technology that barely existed when the shield first bit into the clay. In 1865 the East London Railway Company bought the tunnel, and from 1869 trains ran through it; it was later absorbed into London's Underground network, and today the twin horseshoe arches carry London Overground passengers between Rotherhithe and Wapping, most of them unaware they are riding through the oldest structure of its kind on the planet. The engine house at Rotherhithe is now the Brunel Museum, and the great sinking shaft has become a performance space above the running trains. Marc Brunel's borrowed worm, in other words, is still at work — and every machine now grinding out metros, sewers and rail links beneath the world's cities is following its path.
Quiz nuggets
- The Thames Tunnel, opened on 25 March 1843 between Rotherhithe and Wapping, was the world's first tunnel beneath a navigable river.
- Marc Brunel's tunnelling shield, patented in 1818, was inspired by the shipworm Teredo navalis and held 36 miners working in an iron honeycomb.
- The January 1828 flood drowned six miners and nearly killed the resident engineer — Marc's son, Isambard Kingdom Brunel.
- A banquet was held inside the unfinished tunnel in November 1827, with music from the band of the Coldstream Guards.
- Sold to the East London Railway in 1865, the tunnel has carried trains since 1869 and today forms part of the London Overground.