. How to make and use electricity ... sitedirection to the first, as shown by an opposite deflection. Place within the coil a core of soft iron. Wave back andforth, over one extremity of the core, one of th« poles of a pow-erful bar-magnet. The needle of the galvanometer is violently 38 HOW TO MAKE AND agitated, being deflected in one direction at each approach,and in the opposite direction at each departure. Now repeatthe experiments with the opposite pole of the maguet. Theeffect is, as we should expect, to reverse all the currents. If the permanent magnet is stationary, and the electro-mag-
. How to make and use electricity ... sitedirection to the first, as shown by an opposite deflection. Place within the coil a core of soft iron. Wave back andforth, over one extremity of the core, one of th« poles of a pow-erful bar-magnet. The needle of the galvanometer is violently 38 HOW TO MAKE AND agitated, being deflected in one direction at each approach,and in the opposite direction at each departure. Now repeatthe experiments with the opposite pole of the maguet. Theeffect is, as we should expect, to reverse all the currents. If the permanent magnet is stationary, and the electro-mag-net is moved back and forth, the result is the same as whenthe magnet was moved and the electro-magnet was constructed for the purpose of generating electric-ity in this manner are called magneto electric machines. Figure 3 will give a general idea of the construction of thesimple kinds of magneto machines, such as are used in thetelephone to ring the bells. N. S. is a permanent magnet, composed of several horse-. shoe magnets screwed together. E. E. are coils containingrows of soft iron connected by the back armature C. C, thewhole constituting a sort of an armature to the permanent USE ELECTRICITY. 39 magnet. The brass axle D. D. is rigidly connected with theback armature C. C, so that when the axle is rotated by meansof the crank A, both helices are carried around with it. Now,suppose the crank to be turned; during the first quarter of arevolution a separation of poles occurs, and currents of elec-tricity are establishedin bothhelices. The wire that constitutesthe helix is wound in opposite directions around the two cores,so that two currents may not flow in opposite directionsthiough the wire, and thereby neutralize one another, but mayhave a common direction, and thereby produce a current ofdouble the electro-motive force that would be produced in asingle helix. During the second quarter revolution the poles approachone another, and the effect would be
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectricity, bookyear
