Annular gap (cylindrical body) electro-magnet No. 3, assembled with polar gap approximately 19/16" to 1 1/4", part of Oliver Lodge’s microphone amplifier or relay, 1898 (British patent 9712 of 1898), a precursor of the moving-coil loudspeaker Annular gap (cylindrical body) electro-magnet No. 3, c..1898 1898-1900
Eddy current apparatus, magnetic wheel, with two coils, magnetic tops to rotate wheel, attached to a wooden stand Electro magnet. Part of Branly collection? (66883)