Identifier: conquestofnature00will (find matches)
Title: The conquest of nature
Year: 1911 (1910s)
Authors: Williams, Henry Smith, 1863- Williams, Edward Huntington, 1868-1944, joint author
Subjects: Industrial arts Machinery
Publisher: New York and London, The Goodhue company

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face each other, the lines of magnetic force passingbetween these poles are concentrated into a narrowcompass. With the ordinary bar magnet, as everyoneis aware, these lines of force circle out in everj^ directionfrom the poles in an almost infinite number of loops, allconverging at the poles, and becoming relatively sepa-rated at the equator in a manner which may be graph-ically illustrated by the lines of longitude drawn on anordinary globe. It is obvious that with a magnet of such constructiononly a small proportion of the lines of magnetic forcecould be utilized in generating electricity. But, as al-ready mentioned, when the magnet is so curved that itspoles face each other, the lines of force, instead of widelydiverging, pass from pole to pole almost in a directstream. The strength of this magnetic stream may beincreased almost indefinitely by winding the iron coreof the magnet with the coil of wire through which theelectric current is passed, thus constituting the electro- (i8o)
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THE EVOLUTION OF THE DYNAMO. Fig. I.—A small example of the original commercial form of the drum armature ma-chine, patented in 1873 by Dr. Werner Siemens and F. Von Hefner Alteneck. The armatureis a development of the Siemens shuttle form of 1856, and gives a nearly continuous current.Fig. 2.—Arr early experimental dynamo. Fig. 3.—Ferrantis original dynamo, patented in1882-1883. The field magnets are stationary and consist of two sets of electro-magnets eachwith 16 projecting pull pieces, between which the armature revolves. Fig. 4.—The giganticrotary converters of the Manhattan Elevated Railway. MANS CO-LABORER: THE DYNAMO magnet which has replaced the old permanent magnetin all modem commercial dynamos. An electromagnet may be sufficiently powerful to lifttons of iron. The force it exerts, therefore, is verytangible in its results. Yet it seems mysterious, becauseso many substances are unaffected by it. You mayplace your head, for example, between the poles of themost power

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