Gasholder No 4, former Bromley-by-Bow gasworks

Gasholder No. 4, Former Bromley-by-Bow Gasworks

This gasholder was built between 1876 and 1877 by contractors Westwood and Wrights under the direction of engineer William Bourne Wright. The guide frame was designed by engineers Joseph Clark and Thomas Kirkham, while the gas bell was designed by engineer Vitruvius Wyatt.

The structure stands approximately 23 metres high with a diameter of 62 metres and a capacity of two million cubic feet. It is classified as Type 14 in Tucker's Typology of gasholders. The circular guide frame comprises two tiers of 28 cast-iron columns connected by horizontal cast and wrought-iron girders. The columns and girders are made of cast-iron with decorative cast-iron webs between wrought-iron angles at the top and bottom of each girder.

The lower columns are fixed on substantial moulded cast-iron pedestals featuring fielded panels and oval plaques embossed with the letters "WILLIAM BOURNE WRIGHT / ENGINEER" and "WESTWOOD & WRIGHTS / CONTRACTORS" together with the completion date. These lower columns are cast as Roman Doric columns with moulded bases and capitals. Above each column sits a junction box in the form of an entablature comprising a Doric frieze with triglyphs beneath a cornice. Each cornice is a detachable casting that conceals the structural connection between the lower and upper columns. The lower girders are enriched with filigree cast-ironwork featuring interlaced decorative patterns. The upper tier of columns is cast in a simplified Corinthian order, each topped with a plain frieze. The column proportions vary according to classical principles, progressing from the heavier Doric at the bottom to the lighter Corinthian at the top. The upper girders are decorated with an interlocking circle motif.

Guide rails are attached to the inside edge of each column to accommodate wrought-iron roller carriages for the two lifts of the telescopic bell, which rose when the gasholder filled with gas and fell as it emptied. The crown of the gas bell employs a system of wrought-iron girders developed by Wyatt, comprising I-section ribs with plate or lattice webs—a rare and early surviving example and the only one on the List. It is covered in wrought-iron sheeting with replacement steel handrails at the top.

The in-ground tank is 11.6 metres deep, constructed of stock-brick lined with embedded bands of hoop-iron reinforcement and a concrete bottom. It is topped with Greenmoor stone coping. The tank wall is strengthened by 56 piers and waterproofed on the outside with blue clay puddle to a thickness of 0.6 metres. The gas bell and tank are included in the listing. At the time of inspection, the gas bell was in its non-telescoped resting state following decommissioning, which had caused slight distortion to the crown sheeting, as is typical of such structures.