520
102
}
PING PROJECT.
FILTRATION.
tion to one artifice, by which the carrying capacity of
the catch-water channels may be materially increased, in
some cases at least. The main point at which the catch-
water channels will receive water, will be at the points
where they intersect natural water-courses.
Heavy
showers are not, as a rule, of long duration, and flow off
rapidly. If, on the course of any stream, one or more
reservoirs of small capacity, say of one or two millions
of gallons, could be constructed, the effect would be
to moderate the flow of the stream. The reservoirs
would have to fill, before the flow of the stream
attained its maximum, and before the reservoirs filled,
The contents of these
the storm would have abated.
reservoirs would then flow away,
through a suitably regulated orifice.
The effect would be to equalise
the flow into the catch-water channel, and to bring it
within its carrying capacity.
(14) I agree with Mr Cooper that pumping should
not be introduced at present. The works which he proposes will probably provide a sufficient supply, by
gravitation, for many years to come.
(12) The rate of Filtration proposed by Mr Cooper
is lower than that which is frequently obtained elsewhere.
I presume however that it is based on experience. From
what I observed, I know that the water of Hong Kong is
difficult to filter properly. It is worthy of considera-
tion, whether it would not be well to divide the total
filtering-area into more numerous elements than is
indicated on the plan so as to reduce the proportion
of the filter-beds which are in reserve. This is
14