254
and half this, or 13 tous to the square yard mid
way up, indicates the enormous pressure the dan will
into acerout
have to resist, taking the entire area. It must also be borne in mind that water under pressure, as in this case,
will force a passage through the smallest pore, if such is to be found at any point, and it will be almost impossible to correct or to close such after the dam has been completed.
The estimate will bear to be increased so as to obtain the soundness and security of work aimed at, and yet be much lower in cost than
any
work in England having similar water
storage capacity. I consequently recommend that
these extra costs be allowed so as to give the
Colony
one of the finest and cheapest works in
existence.
J
The tunnel needs no special remartes; as,
being entirely in granite, time for completion is
the