细节
A magnetic detector,
by Marconi's Wireless Telegraph Co. Ltd., London, No. 47873, with spring motor (crank replaced), screw adjustment for tension and teak case stamped 24 -- 18in. (47cm.) wide, circa 1910 (lacking glazed cover)
by Marconi's Wireless Telegraph Co. Ltd., London, No. 47873, with spring motor (crank replaced), screw adjustment for tension and teak case stamped 24 -- 18in. (47cm.) wide, circa 1910 (lacking glazed cover)