B64-722. TANGENT GALVANOMETER. Ziegler Electric Co. Early device used to measure electric current that consists of a compass mounted inside a loop of copper wire; you hook up the current and the deflection of the compass needle with a little figuring gives you the current in amps. Ziegler was a Boston maker of electrical instruments at the end of the nineteenth century. 11" high, 9" diameter. The thread from which the compass needle is suspended needs to be replaced, but otherwise like new. Condition: Good+, Estimate: 100-200