Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . HELIX ON STAND. 165 transverse bands, lying in contact with each other,present the appearance of a closely-compacted form the metal conducting the electricitymay have, the filings will always arrange themselvesin lines encircling it at right angles to the course ofthe current. The iron filings fall off when the cur-rent ceases to flow; but if steel filings be employed,part of them remain attached, in consequence of theadhesion of the ma
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . HELIX ON STAND. 165 transverse bands, lying in contact with each other,present the appearance of a closely-compacted form the metal conducting the electricitymay have, the filings will always arrange themselvesin lines encircling it at right angles to the course ofthe current. The iron filings fall off when the cur-rent ceases to flow; but if steel filings be employed,part of them remain attached, in consequence of theadhesion of the magnetized particles among them-selves. A short wire is better for this experimentthan one of considerable length ; and a battery ofsome power, such as a series of a few pairs ofGroves, may be used with advantage. 262. Helix, on Stand. — The magnetizing powerof the wire is very greatly increased by coiling it in Fig. the manner of a corkscrew, so as to form a hollowcylinder, into which the body to be magnetized canbe inserted. Such a coil is denominated a helia:) 166 DAVISS MANUAL. and is represented in Fig. 107, mounted upon astand. A single circular turn is more efficient thanthe straight wire, and each turn adds to the powerwithin a certain limit, whether the whole forms asingle layer, or whether each successive turn enclosesthe previous one in the manner of a spiral. When ahelix of great power is required, it is composed layers of wire. The wire forming the coilis insulated by being wound with cotton, to preventany lateral passage of the current. 263. Place a bar of soft iron within the coil, andconnect it with the battery by means of the twocups attached to the stand. The two extremities ofthe bar instantly become strongly magnetic, as willbe seen by bringing a key, or other piece of iron, incontact with them. On separating one of the wirescommunicating with the battery, the magnet
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
