g were, however,
of excellent quality; and the tunnel was happily brought to a completion
without any accident.

At Watford the chalk ridge was penetrated by a tunnel about 1800 yards
long; and at Northchurch, Lindslade, and Stowe Hill, there were other
tunnels of minor extent. But the chief difficulty of the undertaking was
the execution of that under the Kilsby ridge. Though not the largest,
this is in many respects one of the most interesting works of the kind in
England. It is about 2400 yards long, and runs at an average depth of
about 160 feet below the surface. The ridge under which it extends is of
considerable extent, the famous battle of Naseby having been fought upon
one of the spurs of the same high ground about seven miles to the
eastward.

Previous to the letting of the contract, the character of the underground
soil was examined by trial-shafts. The tests indicated that it consisted
of shale of the lower oolite, and the works were let accordingly. But
they had scarcely been commenced when it was discovered that, at an
interval between the two trial-shafts which had been sunk, about 200
yards from the south end of the tunnel, there existed an extensive
quicksand under a bed of clay 40 feet thick, which the borings had
escaped in the most singular manner. At the bottom of one of these
shafts the excavation and building of the tunnel were proceeding, when
the roof at one part suddenly gave way, a deluge of water burst in, and
the party of workmen with the utmost difficulty escaped with their lives.
They were only saved by means of a raft, on which they were towed by one
of the engineers swimming with the rope in his mouth to the lower end of
the shaft, out of which they were safely lifted to the daylight. The
works were of course at that point immediately stopped.

[Picture: The Shafts over Kilsby Tunnel]

The contractor, who had undertaken the construction of the tunnel, was so
overwhelmed by the calamity, that, though he was relieved by the Company
from his engagement, he took to his bed and shortly after died.
Pumping-engines were then erected for the purpose of draining off the
water, but for a long time it prevailed, and sometimes even rose in the
shaft. The question then presented itself, whether in the face of so
formidable a difficulty, the works should be proceeded with or abandoned.
Robert Stephenson sent over to Alton Grange for his father, and the two
took serious co