Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity (1854)
Davis, Daniel · Boston : Palmer and Hall · leaf 186
e ends of the wire are left free,in order to be inserted intothe cups of the battery. AtD are shown two semicircularpieces of soft iron, providedwith handles for pulling. Thehandles are attached to thesemicircles, by ball and socket joints, to preventthem from being twisted or wrenched by… … 170 DAVISS MANUAL. semicircbs, by means of the current from a thermo-electric battery, has been mentioned in ^ 129. 272. With thicker semicircles, such as are repre- jYg. 109. sented in Fig. 109, the induced magnetism issufficient to supporta hundred weight ormore, even with asmall battery.…
