Details
A mining air-flow meter,
by Negretti & Zambra, the silvered dial with three subsidiary dials and eight-bladed fan, in leather case -- 4¼in. (10.8cm.) wide
See Illustration
by Negretti & Zambra, the silvered dial with three subsidiary dials and eight-bladed fan, in leather case -- 4¼in. (10.8cm.) wide
See Illustration