Holborn Valley Viaduct: Section Of Subway

Holborn Valley Viaduct [in London]: section of subway, north side, at junction of Charterhouse-Street, 1871. 'In the construction of the Viaduct and the streets connected with it the Corporation of London determined to introduce subways for gas, water, and telegraph pipes, and thus to prevent the breaking up of the road surface, which is so often necessary with the ordinary system of placing them in the ground beneath the public way...The conveyance of gas...requires special arrangements for ventilation to prevent the risk of explosion, and the subways under the Viaduct are believed to be the first constructed with a view to their safety when used for this purpose...there is a subway, 7 ft. wide and 11 ft. 6 in. high, on each side of the road...In each subway a 14-inch main pipe of the New River Company is carried by iron chains near to the wall nearest the frontage of the houses, and above it 10-inch gas mains, belonging to the City of London and Great Central Gas Companies, are supported on iron brackets projecting from the wall; on the opposite side of the subway a pipe containing the telegraph wires is carried in a similar way'. The Holborn Viaduct was designed by William Haywood, 'engineer of the Commissioners of Sewers'. From "Illustrated London News", 1871. Creator: Unknown. (Photo by The Print Collector/Heritage Images via Getty Images)