Electrical subways at the World's Fair

ELECTRICAL DISTRIBUTION AT THE WORLDS FAIR.

Steady progress on the electrical work of the World's Columbian Exposition is being made by the Construction Department and an excellent method of distribution of the conductors devased by the able electrical engineer of the department, Mr. Frederick Sargent, has been adopted.

The general plan of distribution embraces the utilization of the elevated railway structure which will run around the grounds, and the building of a tunnel or subway which will contain such wires and cables as are necessary to supply those buildings which could not be reached from the elevated structure.

It has now been decided to place the electrical generators in the Machinery Building and not in the Annex, as before proposed. The generating plant will he arranged along the south wall of Machinery Building, a space being reserved 850 feet long by 800 feel wide for that purpose; the engines being located near the wall and the dynamos towards the centre of the building. Behind the Machinery Building is a covered alley 80 feet wide; then comes the Boiler House, which will extend the entire length of the Machinery Building, and have a depth of 60 feet, the boilers being set towards the north wall and fuel being delivered at the south end of the house direct from the cars brought clear to the doors on a track running in the rear.

The conductors after leaving the dynamos will be arranged in a suitable fireproof rack located under the main floor about 150 feet from the south wall and running lengthwise of the building. From this rack five distinct groups of feeding wires will start as follows:

The first group will supply all the territory contained in the space bounded by 59th street on the north, centre of basin on the south, Lake Michigan on the east, and the lagoon on the west; also the electric fouutain, located at the west extremity of basin, and comprising the following: Fisheries Building, Government Building, Naval Exhibit, Manufactures and Liberal Arts Building, Electric Fountain and all the grounds within the territory. The main conduit for this group will be provided in the following manner: Starting from the rack already referred to in Machinery Building, a tunnel or subway will be constructed of sufficient capacity to accommodate 150 insulated cables or wires up to 600,000 circular mils area. The tunnel, which is shown in the accompanying engravings. Figs. 1, and 2, will run north from the rack under the floor of Machinery Hall to Electricity Building, with a tap for the electric fountain, the wires for which will be laid on the drawing-in system east from Electricity Building to the bridge, from the bridge to the Manufactures Building. From this point to the north end of the building, a fireproof conduit will be provided, which will gradually diminish in width as the wires are distributed. From the Manufactures Building to the Government Building and thence to the Fisheries Building the tunnel will be about three feet wide, with wires on one side only. The system will terminate at the Fisheries Building.

The tunnel itself, or any of the buildings through which it passes, may be tapped by the drawing-in system, buried in the ground wherever necessary to supply light or power to the grounds or any other buildings that may be erected in this territory. It will be constructed absolutely fireproof throughout. The crossarms will be made of iron provided with holes at suitable points to receive pins, upon which insulators of various form will be placed in the case of special insulators special forms of cross-arms will be provided where required.

Group No. 2 will be provided for in a tunnel of the same capacity as that for the first group, and will run direct from Machinery Hall to Electricity Building, with branch for the Mines Building and tap for the Administration Building. It will also provide for all grounds adjacent to these buildings, and probably include the wooded island.

Group No. 3 will run direct from Machinery Hall to the Elevated Road, and supply all territory north of the Basin and Administration Building not reached by groups Nos. 1 and 2, including Transportation Building, Transportation Annex, Service Building, Horticultural Building, Women's Building, State and Foreign Buildings, Art Gallery, Midway Plaisance and all grounds and smaller buildings in the territory mentioned. The drawing-in systems or buried conductors are to be used wherever elevated structure is not available.

Group No. 4 will provide for Machinery Hall, Machinery Annex, Boiler-House, western portion of Stock Exhibit, and western portion of grounds; the wires to be distributed under basement of buildings and on elevated railway, and thence to grounds and Stock Exhibit by drawing-in or buried systems.

Group No. 5 will provide for: Agricultural Building, Agricultural Annex, Saw Mill, Forestry Building, Dairy Building, eastern portion of Stock Exhibit, Pier and Casino; the wires to be distributed on elevated structure, basement of Agricultural Building, and on the piles under the roadway over the pier so far as practicable, and then by drawing-in or buried systems.

The tunnel system cannot well be continued further north than the Fisheries Building. because of the ground not being of sufficient height above water line. The tunnel systems will all be six feet high in the clear, except from the Manufactures Building to the Fisheries Building, where it can only five feet.

It should be mentioned that other designs are being prepared for the structure of the tunnel, one of which may be preferable to the one illustrated; but in any ease the arrangement of supporting conductors and the general dimensions will be maintained. It is not intended to construct the tunnels until the bulk of the lighting and power transmission is contracted for, so that modifications can be made to most special requirements, if necessary. Manholes will be provided at intervals along the subway to enable the conductors to be placed therein with the greatest facility, and are necessary, since sewers and water-pipes cross the subway at several points, which will not, therefore, permit of walking from one end to the other, although the wires will be arranged in such a manner as to be got at without difficulty.

The facilities afforded by using a combination of the tunnel system, elevated railway structure and basement of buildings, as herein outlined, for the main trunk lines are considered adequate for supplying all the requirements of grounds and buildings, and the whole arrangement is extemely practical. The ease with which any of the wires can be got at is an important and meritorious feature of the plan, which reflects credit on the designer, and which has received the unanimous approval of, and been adopted by, the Committee on Electricity.