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 255
238 Daviss manual. This ring is in metallic connection with one ofthe screw-cups on the base board. Surrounding theFio*. 164. mercury cup is a helix, one of whose ends con-nects with the remainingscrew-cup. Its other endis left free, so as to beinserted into the shallowcup. An iron cup, withits rim…
