The life of George Stephenson, railway engineer - Lighthouse ...

CHAP. XX.] THE RAILWAY ON CHAT MOSS. 233
Manchester, and bought up all the old tallow casks that could be
found ; and, digging out the trench anew, he had the casks in-
serted along the bottom, with their ends thrust into each other,
—thus keeping up the continuity of the drain. The pressure
of the bog, however, on both sides of the casks, as well as from
beneath, forced them out of position ; and the line of casks lay
unequally along the surface. They were then weighted with
clay for the purpose of keeping them down. This expedient
proved successful ; and the drainage proceeded. Then the moss
between the two lines of drains was spread over with hurdles,
sand, and earth, for the purpose of forming the road. But it
was soon apparent that this weight was squeezing down ' the
moss and making it rise up on either side of the line, so that the
railway lay as it were in a valley, and formed one huge drain
running across the bog. To correct this defect, the moss was
weighted with hurdles and earth, to the extent of about thirty
feet outside the line on either side, by which means the adjacent
bog was forced down, and the line of railway in the centre was
again raised to its proper position. By these expedients, the
necessity for devising which was constantly occurring, and as
constantly met with remarkable success, the work went forward,
and the rails were laid down.
Mr. Stephenson himself thus described the general outline of
this formidable work, in an account which he furnished to Mr.
Charles Knight, dated the 1st November, 1828 :*
" Chat Moss extends four miles along the line of road. On
each side of the moss the land lies low. On the western side
an embankment is formed of moss nearly a mile in length and
varying from ten to twelve feet in height, which stands extremely
well. The slopes of this embankment are a little more upright
than an angle of 45°, which, from my experience, stands better
than if more inclined. It is now covered with a material from
two to three feet thick, consisting of sand and gravel. The permanent
road is laid upon this covering, and remains very firm.
The quantity of excavations made in the moss, to form the embankments
adjoining, amount to 520,000 cubic yards. That
* Companion to the Almanac and Year Book of General Information for
1829.
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