Ferranti's planned Deptford Central electricity supply station, 1891.

Avo Smethurst Exposure Meter, c 1930s.

Ferranti's planned Deptford Central electricity supply station, 1891.

Safety matches and Avo Smethurst exposure meter, c 1930s.

Edison electrolyte meter, c 1881.

Electricity meter, c 1930.

Direct-reading ammeter, 1900.

Deptford Power Station, London, c 1888.

Morphy Richards electric toaster, 1962.

Ayrton and Perry ammeters, late 19th century.

pH meter, 1950-1970.

Synchronous mains electric clock of the non self-starting type, c 1936.