Tl NNKI.S THIMtfdH HAKI> H(>CK 117 



M ifmry. The St Gothard tunnel is lined Uiroughout with 

 masonry. After the upper portion of the section waa fully 

 excavated, the roof arch was built with its feet resting upon 

 short planks on the top of the bench. Plank centers were used 

 in constructing the arch. For the arch brick masonry waa 

 employed, but the side walls were built of rubble masonry. 

 Shelter niches, about 3 ft. deep, were built into the side walls 

 at intervals, and about every 3,000 ft. storage nidu-s about 10 

 ft deep, and closed with a door, were constructed. The cul- 

 vert was of brick masonry. 



Mechanical Installation. Water-power was used exclusively 

 in driving the SL Gothard tunnel. At the north end, the 

 Reuss, and at the south end, the Tessin and the Tremola, rivers 

 or torrents were dammed, and their waters conducted to tur- 

 bine plants at the opposite ends of the tunnel. The power thus 

 furnished by the Ileuss was about 1,500 H.P., and the power 

 furnished by the combined supply of the Tessin and Tremola 

 was 1,220 H.P. The turbine plant at both ends at first con- 

 sisted of four horizontal impulse turbines, but later, two nnnv 

 turbines were added at the south end. Each of the two s 

 four turbines first installed drove five groujw of three onupivs- 

 sors each, and the two supplementary turbines drove two groups 

 of four compressors each. The compressors were of the Coll<l>n 

 type with water injection, and four groups of three compressors 

 each were capable of furnishing 1,000 cu. yds. of air compressed 

 to between seven and eight atmospheres every hour, or almut 

 100 H.P. per hour, delivered to the drills at the front This 

 iiir when exhausted provided about 8,000 cu. yds. of fresh air 

 per hour for ventilation. 



The compressors at each entrance discharged into a group 

 of four cylindrical receivers of wrought-iron each 5.8 ft in 

 diameter by 29.5 ft long, and having a capacity of 593 cu. ft 

 The cylinders were placed horizontally, the first one receiving 

 the air at one end and discharging it at the other end into the 

 next cylinder, and so on. By this arrangement the air was 



