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 229
conspire in bringing theelectro-magnet betweenthe poles of the U-mag-net. When it reachesthis position, each seg-ment of the pole-chang-er leaves the spring withwhich it was in contact,and passes to the other.As the bar is movingpast the poles by themomentum it has gain-ed, its magnetism… … Ritchies revolving magnet. 213 it consequently moves on, the polarity being reversedtwice in each revolution. 338. Instead of using a pole-changer, the polesof the electro-magnet are reversed in the followingmanner in the instrument known as Ritchies Re-volving Magnet. The ends of the wire…
