fydrautics. 139

 

First of all he cleared away the floor about the
well, and built up the circular wall of it a foot or
two higher, with stones picked from those lying .-
about, and with mortar which he made him- |
self. By means of a spirit-level, he laid the top
layer of stones quite horizontal; and he intro-
duced into it several blocks of wood instead of
stones.

Next he made a small wooden frame, which, by
driving spikes between the stones, he fastened to
the opening of the underground passage, so that
a well-fitting piece of board could move up and
down in it, by means of a projecting handle, and
be a more manageable sluice than he had hitherto
had.

Then he made a strong wooden lid to the
mouth of the well, and screwed it down to the
wooden blocks he had built in. Through a hole
in it, just large enough, came the handle of the
sluice.

Next, in the middle of the cover, he made
a hole with a brace and centre-bit, and into it
drove the end of a strong iron pipe, fitting tight,
and long enough to reach almost to the top of the
vault. As soon as this was fixed he shut down
the sluice, and in a few seconds the water was
falling in sheets upon him, and flooding the floor,
dashed back from the vault, against which it rushed
ee top of the pipe. This was enough for the

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