Profs. Ayrton and Perry standard inductance
Campbell variable mutual standard inductance no. L-13769
Clark standard element (cell) no. 142
1872
Clark standard cell
Pair of Clark standard cells in one case
Electrically maintained tuning fork, by Muirhead
Standard air capacitor
Pair of Clark standard cells in one case
1/3 microfarad standard condenser
1892
Clark standard cell no. 1297 by Nalder Brothers and Co.
Standard condenser no. 30510
1911
Pair of turned wooden standards
1880-1920