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A sketch by Isambard Kingdom Brunel illustrating how he lowered a diving bell from a boat to repair the hole at the bottom of the river in 1827.
Fascinating plans for the world's first underwater tunnel from the Brunel family archive have come to light and are tipped to sell for £100,000.
The 1,300ft long Thames Tunnel connecting Rotherhithe and Wapping was such an amazing engineering feat it was described as 'the eighth wonder of the world'.
It was designed by Marc Brunel, the father of Isambard Kingdom Brunel who was also involved in the project.
Work on the tunnel, which was 35ft wide, 20ft high and 75ft below the river surface, got underway in 1825, but a combination of unfortunate accidents and spiralling costs meant it took 18 years to build.