THE EAILWAY TUNNEL THROUGH THE ALPS. 
159 
along the rugged slopes, and rises a further height of 334 feet, 
immediately after which it drops down to the ravine in which 
rushes the Torrente del GrauVallon. After crossing the im- 
petuous stream, it rapidly ascends a height of 2,430 feet, till 
it reaches the station La Riond with a further ascent of 
725 feet. From this latter point it skirts the shattered slopes 
of a steep precipice to the Yallonet station with a rise of 
1,004 feet. The line then crosses the apex of the rocks, and 
at once rises precipitously up to the observatory on the 
pinnacle-like summit with a further rise of 246 feet, this sum- 
mit being 9,675 feet above the level of the sea, and 5,714 feet 
above the tunnel mouth at Fourneau. From this point the 
mountain descends with great rapidity over exceedingly rugged 
and broken ground, no less than 3,588 feet at one swoop, to 
the torrent of the Merdovine, which flows down a deep valley. 
It once more rises 380 feet, passing a wild and broken country, 
to the apex of a precipice at the Banda station, from which it 
again falls with a rapid drop of 1,500 feet to the southern 
mouth of the tunnel at Bardonneche, close to the torrent of 
the Rochemolles. 
The heights of some of the Alpine peaks in the immediate 
neighbourhood of the course of the axis of the tunnel reach the 
following elevations, expressed in English feet : — • 
Mont Rond 8,057 Bellcoll ... ... ... 7,886 
Mont Pelonse 10,384 Chabriere 7,358 
Punta di Frejns ... 9,761 
So that the summit of the highest Alp, Mont Pelouse, near 
the line of tunnel, is 10,393 feet above the level of the sea, 
being thus considerably above the limit of perpetual snow, and 
nearly twice the height of the great road over Mont Cenis. 
The preparatory works were of vast magnitude, including 
the construction of new and solid roads, of vaulted canals, 
bridges, magazines, offices, workshops, forges, furnaces, and 
machinery, driven by a turbine of 12 -horse power; extensive 
reservoirs, — some underground, to shelter them from the frost, 
high up on the mountain side ; residences for the men, offices 
for engineers ; being, in fact, a complete and perfect estab- 
lishment of great extent and variety, both at Bardonneche, 
Modane, and Fourneau. 
As the excavation of the tunnel was not to be effected by 
manual labour, nor indeed by steam, other means had to be 
adopted, and new machinery devised for the purpose. The 
power of water, so plentifully supplied by the Alpine snow and 
rain, was the great motive power determined upon, as being 
the most economical and manageable for such a mountainous 
locality ; hence, new hydraulic and pneumatic machinery had 
to be invented, tested, varied and improved. Water was the 
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