Page:Popular Science Monthly Volume 43.djvu/743

Rh beneath, as the triangle is swung to and fro under the impulses of an electro-magnet. The visitor will also have an opportunity to examine the new telautograph of Prof. Elisha Gray, by means of which the written word, it is promised us, may be transmitted to a distance with the same facility that the spoken word now is by telephone. Turning from this lighter and more delicate form of apparatus, the visitor will find a very complete display of the class of applications that has brought electricity into such close contact with the daily life of the masses in recent years. From the great Westinghouse lighting installation and from the power plant of the intramural he will get some adequate idea of a modern central-station equipment, while from the illustration of long-distance power transmission he will be able to comprehend one of the directions in which electricity holds out the greatest promise for the future. In the exhibits of electric welding and forging he will learn of the help the electric current is giving to the metal worker, and in that of cooking and heating the attempts that are being made to displace with electrical appliances the kitchen range and the hot-air furnace.

The most prominent exhibit of electricity at the fair is undoubtedly the lighting of the Exposition itself. This is carried out along lines already well established, and is remarkable chiefly for the great scale upon which it is planned and executed. Nearly five thousand arc lamps and a hundred thousand incandescents have been called into requisition for the illumination of the grounds and buildings. The placing of these required, no doubt, a great deal of detail work and called for nice discrimination in adapting means to ends, but involved no electrical problems of especial novelty. The lighting of the big Manufactures Building, with its thirty acres of main floor space and ten acres of galleries, presented the most difficult problem to the Exposition authorities, but this has been successfully solved by the use of the arc lamp hung from immense coronas along the central line of the building, supplemented by individual lamps in the corridors, galleries, and separate rooms. The coronas are hung a hundred and forty feet from the floor and sixty feet from the crown of the great arched roof which spans the structure, and are of colossal size, the central one being seventy-five feet in diameter and the two which flank it on either side sixty feet. Something over four hundred lamps are disposed of in this way, while to these are added some twelve hundred more to complete the lighting of this great inclosure. The incandescent, so flexible in the hands of the decorator, has been used very effectively to outline the buildings and the waterways of the Exposition, in addition to their use in interior illumination.