Kelvin Quadrant Electrometer, 1866
1866
Peltier Type Electrometer, 1848
1845
5KV Ionisation Tester type 732 by Airmec Laboratories Ltd.
1971-1990
Precision ratio comparison bridge type VLF51A
1976-1985
Ayrton and Perry ammeter, about 1880
1875-1884
Hibberts magnetic Standard no. 9
1890-1910
Kelvin Type Quadrant Electrometer, 1857
1857