THE YPRES TIMES
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a mine would be blown. Sometimes by remote control of dummy picks in a temporarily
evacuated gallery within range of a suspected hostile mine, the enemy was encouraged
to end a period of suspense.
At Hill 60 conditions were entirely different. Here the uppermost two or three
feet of soil consisted of a rich loamy clay. This rested on some twenty feet of firm dry
sand with a six foot layer of very wet quicksand separating it from underlying hard blue
clay. As a result of the water-bearing stratum mining operations were considered as
belonging to one of two classes
shallow or deep. The former rarely
extended to the quicksand, and,
though largely carried on for defen
sive purposes, were also undertaken
with the object of misleading the
enemy or for subsidiary purposes
of attack. The latter, essentially
offensive, sometimes reached a
depth of one hundred feet.
While mining in undisturbed
chalk could be carried on with little
or no timbering below a certain
depth, the sands and clays of
Flanders invariably demanded sup
port for the roofs and generally the
sides of tunnels as well. At Hill 60
shallow galleries were close-timbered
with standard mine sets. These
consisted of a pair of upright three-
inch plank, with transverse floor
and lintel boards framed to fit into
and hold them in position without
nailing. In deep mining, double
sets, or five-inch pit props with
longitudinal lagging, were sometimes
required to resist pressure of the blue
clay, though the difficulty of placing
lagging noiselessly precluded its use
close to the enemy. Main galleries
measured 2f feet in width by 4T in
height. Opening off them small THE BERLIN SAP.
branches, called rabbit holes," 2
feet by 3 feet, were driven out either as listening posts or as feelers, or wherever it
became necessary to move forward comparatively short distances at maximum speed.
In blue clay material was excavated by an operator reclining face up and feet
forward, with his shoulders braced against a plank placed across the last set erected.
He used, for the purpose, the special spade known as a grafting tool, which he drove
into the earth with his heel. Elsewhere, where silence replaced speed as the controlling
factor, a bayonet or sharp trowel was employed. In both cases the spoil was deposited
in sandbags, hauled aloft and disposed of at night.
The railway cutting adjoining Hill 60 provided a convenient starting point for one
of these deep offensive mines. Known as the Berlin Sap, a 4 by 6 foot gallery had been
opened off the north face. It was driven in level 75 yards, curving right handed, and
then, inclining down through the quicksand, passed beneath the roadbed. When the
Canadians took over it had reached a point directly under the overhead bridge. They
