Serial No. L128639
Cambridge sub standard ammeter Dynamometer moving coil ammeter in polished wooden case, 0-2-20 FSD Amperes AC 20-150 Hz. Working. Cambridge Instruments, Cambridge, UK. 1941
This is one of many instruments collected by Jack Davidson C Eng FIEE which I have been given by Dr Graham Winbolt
I have two calibration certificates one dated 1941 and the second 1944
Instructions and calibration details on underside of lid.