[Electric engineering.] . nd the pressure across eachlamp 100 volts. We may connect anynumber of such series of five lamps acrossthe mains, and if one light goes out, itputs out the other four in the same cir-cuit with it. Also, if any lamp were cutout, by short-circuiting it, the voltageon the other four lamps would becomehigher than they could stand, becausethe pressure between the mains is con-stant, and cutting out the drop throughone lamp simply throws that much morepressure on the others. As stated above,this method of connecting lamps is used principally inplaces where it is desired to
[Electric engineering.] . nd the pressure across eachlamp 100 volts. We may connect anynumber of such series of five lamps acrossthe mains, and if one light goes out, itputs out the other four in the same cir-cuit with it. Also, if any lamp were cutout, by short-circuiting it, the voltageon the other four lamps would becomehigher than they could stand, becausethe pressure between the mains is con-stant, and cutting out the drop throughone lamp simply throws that much morepressure on the others. As stated above,this method of connecting lamps is used principally inplaces where it is desired to operate lamps on power cir-cuits, the voltage of which is usually higher than that ofthe lamp. Fig. 23 shows a multiple-series arrangement withtwo lamps in series, a scheme of connection sometimesused for operating lamps on 220-volt power circuit, forexample, in mine-haulage plants. By adding the middle,or neutral, wire to Fig. 23, we get the three-wire system,Fig. 24, so extensively used for distribution in large Fig. 24. § 16 ELECTRIC LIGHTING. 41 The schemes of connection given above cover most ofthe cases met with in practice. Their use in connectionwith the different systems of distribution will next beconsidered. SYSTEMS OF DISTRIBUTION. 49. It will be necessary to take up at this point thedifferent systems commonly used for supplying the elec-trical energy to the lamps. The methods of distributingthe current to the lamps by means of the wiring in thebuilding will not be considered here, as that part of thesubject belongs properly to interior wiring and will betaken up in connection with that subject. The followingbrief descriptions of the more important distributing sys-tems are intended to point out how the methods alreadydescribed are applied to electric-lighting work. Current forelectric lighting is distributed from the station to the pointof utilization in the same manner as for power transmission;in fact, in the majority of cases the electric energy trans-
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