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 194
INCLINED B. EVOLVING BAR. 177 … the change produced in the direction of rotation by altering the course of the current. The helix, which ^ ,^^ surrounds the lower end Fig. 116. of the bar, is representedin section, in order to showa wide glass tube within,which can be filled withmercury. The iron barrests in an agate cup atthe…
