A phosphorescent vacuum tube, the pear shaped bulb containing mineral sample, with stem and ebonised stand - 13in.high; and a horizontal paddle wheel vacuum tube
see Front Cover illustration (part lot) (2)
A phosphorescent vacuum tube, the pear shaped bulb containing mineral sample, with stem and ebonised stand - 13in.high; and a horizontal paddle wheel vacuum tube
see Front Cover illustration (part lot) (2)
