Isambard Kingdom Brunel
Thames Tunnel

Brunel worked for several years as an assistant engineer on the project to create a tunnel under London's River Thames between Rotherhithe and Wapping, with tunnellers driving a horizontal shaft from one side of the river to the other under the most difficult and dangerous conditions. The project was funded by the Thames Tunnel Company and Brunel's father, Marc, was the chief engineer. The American Naturalist said, "It is stated also that the operations of the Teredo suggested to Mr. Brunel his method of tunnelling the Thames."

The composition of the riverbed at Rotherhithe was often little more than waterlogged sediment and loose gravel. An ingenious tunnelling shield designed by Marc Brunel helped protect workers from cave-ins, but two incidents of severe flooding halted work for long periods, killing several workers and badly injuring the younger Brunel. The latter incident, in 1828, killed the two most senior miners, and Brunel himself narrowly escaped death. He was seriously injured and spent six months recuperating, during which time he began a design for a bridge in Bristol, which would later be completed as the Clifton Suspension Bridge. The event stopped work on the tunnel for several years.

Though the Thames Tunnel was eventually completed during Marc Brunel's lifetime, his son had no further involvement with the tunnel proper, only using the abandoned works at Rotherhithe to further his abortive Gaz experiments. This was based on an idea of his father's and was intended to develop into an engine that ran on power generated from alternately heating and cooling carbon dioxide made from ammonium carbonate and sulphuric acid. Despite interest from several parties, the Admiralty included, the experiments were judged by Brunel to be a failure on the grounds of fuel economy alone, and were discontinued after 1834.

In 1865, the East London Railway Company purchased the Thames Tunnel for £200,000, and four years later the first trains passed through it. Subsequently, the tunnel became part of the London Underground system, and it remains in use today, originally as part of the East London Line now incorporated into the London Overground.
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