. Electric transmission of power : its present position and advantages. polarity of the It will be seen that this constitutesa double machine, each series of coils, with its commutator,being capable of use independently of the other; but inpractice the electrical connections are so made that thecurrents generated in the two series of armature coils passthrough the field magnet coils, and are joined in oneexternal circuit. This form of armature also presents considerable un-covered surface of iron to the cooling effect of the air, but,like that of the Brush, presents considerable resist
. Electric transmission of power : its present position and advantages. polarity of the It will be seen that this constitutesa double machine, each series of coils, with its commutator,being capable of use independently of the other; but inpractice the electrical connections are so made that thecurrents generated in the two series of armature coils passthrough the field magnet coils, and are joined in oneexternal circuit. This form of armature also presents considerable un-covered surface of iron to the cooling effect of the air, but,like that of the Brush, presents considerable resistance torotation. In the Wallace-Farmer machine there is considerableheating of the armature, the temperature being sometimessufficiently high to melt sealing-wax. In the Siemens machine, the conductor of insulatedcopper wire is coiled in several lengths and convolutions, THE WALLACE-FAEMER AND SIEMENS MACHINES. 21 upon a cylinder shown in transverse (Fig. 15), and in endview by Fig, 16. Each convolution is parallel to the Fig. r 1 H<t !.-?.« r:r--t ^ «c T^ longitudinal axis of the cylinder, and the whole surface ofthe cylinder is covered with wire, laid on in six sections. Fig. 16. rif< ( :.il : T ...i: 1 1. ^
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondon, bookyear187
