ClipArt ETC
"An electrodynamometer is a galvanometer with two coils, at least one of which is movable, and through at least one of which the curent to be measured passes. It is very useful in the measurement of alternating curernts and voltages." -Avery 1895

Electrodynamometer

"An electrodynamometer is a galvanometer with two coils, at least one of which is movable, and through…

F, fixed coil; D, movable coil; S, spiral spring; T, Torsion head; MM, Mercury cups; I, Index needle.

Siemens Electrodynamometer

F, fixed coil; D, movable coil; S, spiral spring; T, Torsion head; MM, Mercury cups; I, Index needle.