128 TrNNELIKG 



electric motor, driving a 75 H.P. air compressor, and of small 

 motors to drive a Sturtevant blower for ventilation, to run the 

 blacksmith shop, and to light the tunnel, shop, and yards. 

 From the compressor air was piped into the tunnel at the 

 east end, and also over the mountain to the west portal work- 

 ings. Two drills were used at each end, and the air was 

 also used for operating derricks and other machinery. For 

 removing the spoil a trolley carrier system was employed. A 

 longitudinal timber was fastened to the tunnel roof, directly 

 in the apex of the roof arch. This timber carried by means 

 of hangers a steel bar trolley rail on which the carriages ran. 

 Outside of the portal this rail formed a loop, so that the 

 carriage could pass around the loop and be taken back to 

 the working face. Each carriage carried a steel span of l cu. 

 ft. capacity, so suspended that by means of a tripping device 

 it was automatically dumped when the proper point on the 

 loop was reached. 



Niagara Falls Power Tunnel. The tail-race tunnel built 

 to carry away the water discharged from the turbines of the 

 Niagara Falls Power Co., has a horse-shoe section 19 x 21 ft. 

 and a length of 6,700 ft. It was driven through rock from 

 three shafts by the center-cut method of blasting. In sink- 

 ing shaft No. very little water was encountered, but at shafts 

 Nos. 1 and 2 an inflow of 800 gallons and 600 gallons per 

 minute, respectively, was encountered. The principal plant 

 was located at shaft No. 2, and consisted of eight 100 H. P. 

 boilers, three 18 x 30 in. Rand duplex air compressors, a 

 Thomson-Houston electric-light plant, and a sawmill with a 

 capacity of 20,000 ft. B. M. per day. The shafts were fitted 

 with Otis automatic hoisting engines, with double cages at 

 shafts Nos. 1 and 2, and a single cage at shaft No. 0. The 

 drills used were 25 Rand drills and three Ingersoll-Sergeant 

 drills. The pumping plant at shaft No. 2 consisted of four 

 No. 7 and one No. 9 Cameron pumps, and that at shaft No. 2 

 consisted of two No. 7 and two No. 9 Cameron pumps and 



