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Show Tnnnrl Building. The art of tunneling may be considered consid-ered as having been reduced to a science, as no distance is too great and no material too bard to be penetrated if the object sought is suillcietit to justify jus-tify the expense. The building of the St. Clair river tunnel where iron cylinders cy-linders were forced through the clay by hydraulic pressure, was a great advance ad-vance in the art of building tunnels through certain kinds of 6oil. The tunnel built under the streets of London, Lon-don, where the top of the arch is just below the cobble stono pavement, was built without in the least obstructing travel at the place where the work was being carried on. According to the Industrial World, a tunnel live miles long is now being driven through the solid rock under Gray's Teak, sixty miles west of Denver, Colo. This tunnel, tun-nel, which is 18x18 feet, is being built primarily to tap the mineral veins in the mountains, which are thought to be quite rich. After the tunnel is complete com-plete it will be enlarged and opened for traffic to accommodate an extension of the Utah Central railway, which is to form a through line from Denver to Salt Lake. Thus far about a mile of the tunnel has been driven by hand power, but a plant of ten Rand drills, with Ingersoil air compressors, has just been put in, and an electric light plant is soon to follow, after which it is expected the rate of working will be greatly increased. The excavating of this tunnel is through rocic about as bard as any that can be found. |