The manner in which Isambard Brunel’s attention was first, we may say accidentally, directed to the subject of tunneling is extremely interesting.
It was in the year 1814, and while superintending some extensive works which were in course of erection at the dockyard at Chatham, where he had just completed a small underground passage, that he observed lying in the dockyard a portion of the old keel of a vessel which had been much perforated by a sea worm termed the Teredo navalis and which, having been sawn longitudinally, afforded a fine view of the perforations these animals had made. His first observation was merely casual, and he passed on, but having arrived at his own small passage or driftway, the thought occurred to him that these worms had made diminutive tunnels. He immediately returned to the spot, and carefully examining what he now regarded with the greatest interest, he observed that the head of the worm was in the form of an auger, by means of which it slowly bored its way through the wood, being very cautious not to approach too near to the water, and leaving as it advanced a secretion behind it which, slowly hardening, formed an impervious lining to its tunnel. Improving on the first idea, Isambard inquired whether a similar principle of operation might not be extended to, and practically made use of, in the construction of tunnels on a large scale. He shortly afterward made a design for forming a subaqueous tunnel of a circular form, by means of an immense iron “worm,” having an auger head, and which was to bore its way through the ground by being slowly turned around, cast-iron segments being inserted behind it as it advanced, which were to have been afterward lined with brickwork until the wall was of the requisite strength.
Henry Law, from “A Memoir of the Several Operations and the Construction of the Thames Tunnel.” In 1809 the Cornish inventor Richard Trevithick failed in his attempt to drill a tunnel beneath the Thames. Ten years later Marc Isambard Brunel patented his tunneling shield. He began work on the Thames tunnel in 1825. When Law was thirteen, he went to work in Brunel’s office, eventually joining the staff of the Thames Tunnel Company, where he remained until the project’s completion in 1843. The world’s first underwater tunnel was converted to rail use in the 1860s.
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