The Collaborative International Dictionary
Galvanoscope
Galvanoscope \Gal*van`o*scope\, n. [Galvanic + -scope: cf. F. galvanoscope.] (Elec.) An instrument or apparatus for detecting the presence of electrical currents, especially such as are of feeble intensity.
Wiktionary
galvanoscope
n. a device used to detect electric currents using the deflection of a magnetic needle