細節
A single-valve Note Magnifier
by the British Wireless Supply Co. Ltd., Leeds & London, P. O. regd. no.3082, with valves, rheostat knob and BBC mark, on marbled composition panel with mahogany plinth base
by the British Wireless Supply Co. Ltd., Leeds & London, P. O. regd. no.3082, with valves, rheostat knob and BBC mark, on marbled composition panel with mahogany plinth base