Potentiometer with set of contacts operated by depressing control shaft Potentiometer with set of contacts
Potentiometer type 4025C, no.137931, by H. Tinsley and Co. Ltd., London, SE25, England, 1950-1960. Potentiometer type 4025C 1950-1960
Potentiometer type 4025 no.106073, by H. Tinsley and Co. Ltd., London, SE25, England, 1950-1960. Two-dial type with three ranges selected by plugs and additional dial to adjust for standard cell e.m.f. Potentiometer type 4025 no.106073 1950-1960