ELECTRICITY AT THE WORLD'S FAIR. 725 



The power and machinery which give vitality to this vast 

 array of lights are to be found in Machinery Hall, and constitute 

 one of the chief electrical exhibits. The most striking feature of 

 this exhibit is the great Westinghouse alternating plant, which 

 supplies the current for the incandescent lamps. It consists of 

 twelve enormous alternating-current generators, each having a 

 capacity of ten thousand sixteen candle-power lamps and requir- 

 ing a thousand horse power apiece to drive them. They are 

 arranged in two groups, the first six of which are coupled direct 

 to Westinghouse upright engines. Of the remaining six, four are 

 driven separately by different makes of engines, and two are belt- 

 driven in tandem fashion by an Allis-Corliss cross-compound en- 

 gine nominally rated at two thousand horse power, but which may 

 be worked up to three thousand horse power upon occasion. This 

 engine is one of two of the same type and by the same maker, 

 the other one being stationed in the power house of the intra- 

 mural railway, and is regarded as a very fine example of modern 

 steam engineering. The alternating generators themselves are of 

 a type only recently devised, in which there is a double row of 

 field poles, and a double set of armature coils, by means of which 

 the machines can supply two separate circuits for the require- 

 ments of incandescent lighting, or furnish what is known as a 

 two-phase current for use with alternating- current motors. The 

 current as generated has a pressure of two thousand volts, which 

 is reduced down, at the point of consumption by means of con- 

 verters, to fifty or a hundred volts. 



Besides the " alternators/' as these machines are technically 

 termed, there are a large number of direct-current machines in 

 this building supplying the currents to the arc lamps, and the 

 motors scattered through the various buildings. The plan 

 adopted by the Exposition authorities has been to confine the 

 engines and boilers to Machinery Hall, so that all the power re- 

 quired in the Exposition except that for the intramural railway, 

 is generated here and transmitted by electricity through under- 

 ground conduits to the place where it is to be used. The exhibi- 

 tion is therefore an illustration of the electric transmission of 

 power upon a large scale, and should furnish a basis for the col- 

 lection of instructive data. 



The feature of the Exposition which will command the most 

 interest of any of those in which light plays a prominent part will 

 probably be the electric fountains. Fountains of this charac- 

 ter have been features of a number of exhibitions since 1884, when 

 the first one, designed by Sir Francis Bolton, was shown at the 

 Healtheries in London, but those at Chicago are upon a much 

 greater scale than any heretofore attempted. The principle of 

 operation is that of throwing a powerful beam of light from be- 



