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Apparatus for entertainment and teaching, advertising in the case of the means on the bottom side of a plate moving magnet, preferably with an armature shown in figs. - can be provided on the upper side of the plate are movable
Apparatus for entertainment and teaching, advertising in the case of the means on the bottom side of a plate moving magnet, preferably with an armature shown in figs. - can be provided on the upper side of the plate are movable