Serial No. AB 89628
Sangamo Weston 0-50mA FSD direct current meter. This large 400X400 mm Bakelite model S66 Laboratory Standard moving coil milliammeter is housed in a wooden case. The meter has a glass thermometer, spirit level and four levelling screws on base. Working. Date unknown. Enfield, London.UK.
Close up view of meter scale showing diagonal markings to facilitate accurate readings.
This is one of many instruments collected by Jack Davidson C Eng FIEE which I have been given by Dr Graham Winbolt.
These advertisements from 1948 and 1960 describe this instrument.
Edward Weston [1850-1936] founded the Weston Electrical Instrument Company and held 334 patents. You will find information about Sangamo in this link as well.