Ornamental gas table lamp, British, late 19th century.
© Science Museum / Science & Society Picture Library
This lamp, with a glas shade decorated with birds and flowers, incorporates a 'London' governor for regulating the gas presure and keeping the burner constant even if the mains presure varied. It consisted of a horizontal membrane carrying at its centre a regulating valve. If gas presure rose the governor's diaphragm flexed in such a way that the gas pasage was reduced, and vice versa. It was claimed that a properly matched governor could result in a 50 to 100 per cent increase of light.