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 114
ive tendency of a magnetin reference to an electric currento 156. Astatic Needle, — A magnetic noedle, socontrived that its directive tendency in respect to the earth is neutralized, so that it s shall remain at rest in any po- N sition, is called an astatic needle. It is constructed as represented… … 98 Daviss manual. magnetic influence of the earth, as whatever forcesmay be exerted upon the upper needle will becounteracted by equal forces exerted in reverse di-rections upon the lov/er. It would be the same,indeed, with the influence exerted by the current oielectricity, if the wire could be…
