Patent no. 2022117, model 1, serial no. 404. Set up on a wood box, containing battery cell. This instrument was acquired and modified by Wilfred Mann (the accused “fifth man” of the Philby spy ring) when he was at Chalk River. Later it was used by Mann in the radiation dept. of the NBS. Designed by C.C. and T. Lauritsen. Mfg: Fred C. Hensen Co., Pasadena, CA.
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