Twentieth century handbook for steam engineers and electricians, with questions and answers; a practical nontechnical treatise .. (1916)
Swingle, Calvin F. (Calvin Franklin), b. 1846 · Chicago, F.J. Drake & company · leaf 1347
Fig. 614switch board instrument a certain spot and stop dead. This is called a dead beatneedle. Some instruments have electro-magnets instead of per-manent magnets. The Thomson Astatic instruments areof this type. Two of these instruments are shown in Figs.615 and 616. This latter has a scale or… … Fig. 615switch board ammeter
