This was the culmination of over a century of development of current-measuring instruments which relied on the interaction of currents with static magnetic fields. These instruments were mounted on a solid wall to prevent vibration, and a telescope and curved scale combination used to determine the deflection of the galvanometer. Because of its great sensitivity, you had to plan your measurements so that the coil did not burn out from putting currents of the order of tens of milliamperes through it.
Property of the W&L Physics & Engineering Department
“Wall Galvanometer,” Digital Exhibits at Washington and Lee University Library, accessed January 23, 2018, http://omeka.wlu.edu/items/show/199.