Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . tional view of one of them isgiven separately at A. It con-tains a cavity in the form of ahollow cylinder, adapted to re-ceive one half of the coil seenat C, the remaining half pass-ing into the other cylinderwhen they are fitted longitudinal opening on oneside of the cylinders allowsthe wires of the coil to passout. In this arrangement, thecylinders adhere with greatforce when in contact; but assoon as the current ceases,their magnetism in
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . tional view of one of them isgiven separately at A. It con-tains a cavity in the form of ahollow cylinder, adapted to re-ceive one half of the coil seenat C, the remaining half pass-ing into the other cylinderwhen they are fitted longitudinal opening on oneside of the cylinders allowsthe wires of the coil to passout. In this arrangement, thecylinders adhere with greatforce when in contact; but assoon as the current ceases,their magnetism instantly dis-. 172 DAVISS MANUAL. appears, and the adhesion does not continue as withthe semicircles. When one of the cylinders is passedover the coil, the part exterior to the coil exhibits nosensible polarity. 275. Ribbon Spiral. — Fig. 112 represents astrip of sheet copper, coiled into a spiral. This c instrument is described hereFig. 112. j5 . ^. *^ in consequence oi its possess-ing considerable magnetizingpower, though its principaluses will not be mentionedtill the subject of electro-dynamic induction comes un-der consideration, in bookIII, chapter I. The copper ribbon may be an inchwide and one hundred feet long, the strips being cutfrom a sheet, and soldered together. Being thenwound with strips of thin cotton cloth, it is coiledupon itself, like the mainspring of a watch; insteadof covering it with cotton, it may be coiled with astrip either of cotton or list intervening. Twoscrew-cups are soldered to the ends of the ribbon;the internal end, for convenience, is brought fromthe centre, und
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
