Cubic black box with ten brass contacts over which a rotary contact wiper moves; the wiper is rotated by a black knob.
Inscriptions & markings
Inscribed on top: “Inductance”, “Type 17-B”, “10 x 1mH”, “Muirhead & Co. Ltd No. 133549”, “PI 111”. Burnt in white on front: “MUIRHEAD”. Label on front: “Purchased by UNIVERSITIES COMMISSION”
