MKOIANICAL INSTALLATIONS FOR TUNNEL WORK 129 



three Snow pumps. An auxiliary boiler plant consisting of 

 t\\<> t!0 II. 1'. boilers was located at shaft No. 1, and another, 

 consisting of one 75 H. P. boiler, was located at shaft No. 0. 



Cascade Tunnel. The Cascade tunnel was built in 1886- 

 88 to cany the double tracks of the Northern Pacific Ry. 

 through the Cascade Mountains in Washington. It is 9,850 ft. 

 long with a cross-section 16 \ ft wide and 22 ft high, and 

 is lined with masonry. The material penetrated was a basaltic 

 rock, with a dip of the strata of about 5. The rock was 

 excavated by a wide heading and one bench, using the center- 

 cut system of blasting. A strutting consisting of five-segmrnt 

 timber arches earned on side posts, spaced from 2 ft. to 4 ft 

 apart, and having a roof lagging of 4 x 6 in. timbers packed 

 above with cord-wood. The mechanical plant of the tunnel is 

 of particular interest, because of the fact that all the machinery 

 and supplies had to be hauled from 82 to 87 miles by teams, 

 over a road cut through the forests covering the mountain 

 slopes. This work required from Feb. 22 to July 15, 1886, to 

 perform. In many places the grades were so steep that the 

 wagons had to be hauled by block and tackle. The plant n in- 

 sisted of five engines, two water-wheels, five air compressors, 

 eight 70 H. P. steam-boilers, four large exhaust fans, two m- 

 plete electric arc-lighting plants, two fully equipped machine- 

 shop outfits, 36 air drills, two locomotives, 60 dump cars, ami 

 two sawmill outfits, with the necessary accessories for these \.ui- 

 ous machines. This plant was divided alxmt equally between 

 the two ends of the tunnel. The cost of the plant and of 

 the work of getting it into position was $1*25,000. 



Graveholz Tunnel. The Graveholz tunnel on the Bergen 

 Railway in Norway is notable as being the longest tunnel in 

 northern Europe, and also as being built for a single-track 

 narrow-gauge mil way. This tunnel is 17,400 feet long, and in 

 located at an elevation of 2,900 ft above sea-level. Only 

 about 3% of the length of the tunnel is lined. The mechani- 

 cal installation consists of a turbine plant operating the v 



