Chicago World's Fair — Pluto insulator

The Conduit on the World's Fair Grounds.

To provide for carrying the immense number of wires from the central power station in the Machinery Hall on the World's Fair grounds to the electrical and other buildings where current is to be used, an immense conduit 64 feet square has been built directly under the Machinery Hall. This conduit extends across the grounds only very slightly below the surface to the Electrical Building, from which branches are carried to other sections of the grounds. The accompanying illustration gives a good idea of the construction of this conduit. It has a timbered framework, and is completely inclosed by thick planking spiked to the frame work on the outside. The studding, a part of which is shown at the left of the illustration, is composed of 3 X 6 inch timbers set about 9 or 10 inches apart. The arms for carrying the wires are attached to the cribwork by means of cast iron socket frames, which are attached by heavy lag screws to the studding, as shown in the illustration. These iron frames are made with a number of deep sockets into which arms are driven and which afford a broad and ample bearing surface for their support. The arms are driven back against the planking on the outside of the cribwork. Over the inside of the studding is placed a covering of latticework, shown in the illustration, to which is attached an artificial plaster board, so that the framework of the conduit is entirely sealed. On the cross arms are carried ordinary insulators to which the cables are attached in the usual way. Arms are carried on both sides of the conduit and are just long enough to leave space in the centre for a man to walk through conveniently whenever it is necessary to inspect the wires or to make any repairs. The floor of the conduit is slightly V-shaped to carry off any water which may get into the conduit. The illustration shows the entrance to the conduit directly under the power house. The whole construction is substantial, inexpensive and permits of ready access to the wires which are carried through the subway.

The Love Electric Conduit.

Electric Subway on the World's Fair Grounds.