MESSRS. GAMBRELL BROS, have recently introduced a resistance-box of improved design, which give's promise of eliminating several of the disadvantages of the usual post-office pattern. Fig. 1 shows the appearance of the box with the cover removed to show the working parts. The coils, which hang vertically in the lower part of the box, are brought up to terminal studs (T) seen in Fig. 2, arranged in five rows, one of which, in two sections, forms the “ratios” used as two arms of the bridge.