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began to be felt. Fortunately for tbe advance of the work, a 
method of boring rock, by machinery worked by compressed 
air conveyed in tubes to great distances without losing its 
elastic force, was introduced, and after certain modifications 
was found to work admirably. The compressed air is intro- 
duced to work a piston rod much in the manner in which steam 
is made use of in the small engines called donkey-engines, and 
the power thus obtained communicates a rapid stroke to a 
heavy boring chisel placed horizontally, followed by a recoil 
and slight twist. In the course of the first two minutes of an 
experiment made in the presence of the writer, a hole was 
bored about an inch and a half in depth, and of about the 
same diameter, in a large block of the very hardest and toughest 
quartzite. Seventeen such machines at a time can conveniently 
be placed and worked in the end of the tunnel, and the rock 
thus bored is afterwards blasted. The rapidity of the work is 
so great, that during a single month (May 1867) as much as 
90*60 metres (99 yards) has been completed on the Italian side 
only, being an average of about ten feet per day. The present 
rate of advance averages about eight feet per day on each side, 
and at this rate the work will probably be completed, and, if 
so, communication will be opened from one side to the other 
at the end of the present year.* The whole line is expected 
to be open for traffic in the course of the year 1871. 
It has been stated above, that in order to secure a convenient 
and even a practicable railway line it was necessary to tunnel 
through the crest of the Alps, and that a part of the chain was 
selected where the crest was by no means the lowest. It may be 
thought that an easier line might have been selected, and to 
understand the advantage of the Mont Cenis line some con- 
sideration must be given to the physical geography of this 
part of Europe. The Alpine system, although a part of the 
great mountain axis of the old world, terminates for a short 
space with a broad shoulder of mountain land, forming the 
Maritime, the Fauphiny, and part of the Savoy Alps and 
reaching the Mediterranean. From the Lake of Geneva to 
the Mediterranean there is, therefore, a continued and almost 
uninterrupted succession of mountains. A part of this is a 
confused and most impracticable — and therefore little visited 
On July 15, 1870, a few days after which the writer was on the ground, 
the exact state of the tunnel was as follows : — 
mfctrea. yards. 
From the Italian side . 0,043-20 = 7,205-45 
From the French side . 4,761-80 = 5,208 
Remains to be done . 815 00 = 891-34 
Total length of tunnel 12,020 00 = 13,304-79 
