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The best effect is achieved when the water-
fall connects two small pools. The pools and
the connecting structure should be made at
the same time, and the fall part should be leak-
proof-a leaking waterfall is just as exasperating as a leaky pond. If there is to be more than
one step, then the first step down should be,
virtually, part of the upper pool, and the
first step up part of the lower. The intervening
area is excavated some three inches deeper
than its finished surface will be and the slabs
of stone set in the concrete before it hardens.
A point to observe is that the water does not
run over the sides of the fall. Ferns and other
bog loving plants may be set along the fall
and then if there is any overflow it will do the
plants good.
A tap, hidden by tall marginal plants,
supplies the initial flow of water. A mere
trickle is sufficient for the small waterfall and
the best way of using the overflow is to have
a bog garden around the lower pool. If there
is partial shade the effect is delightful.
One final remark on waterfalls. Some time
ago I was asked to enquire into the mysterious
behaviour, and subsequent death, of the fish
in a certain pool. It had been constructed
about six months previously and was, to all
intents and purposes, cement-poison proof.
Yet the fishes behaved as though some powerful
alkali was irritating their skins. A small
waterfall had been constructed subsequently,
above the pond, and this was made of concrete.
The pond had been scrubbed with a strong
permanganate of potash solution, but the
waterfall had not and it was from this that the
poison came.
Needless to say arrangements must be made
with the local Water Board if either a fountain
or waterfall is to be used.
In the upper pool of the waterfall there will
be a certain amount of movement in the water
and, while the ordinary oxygenating plants
will not object, water lilies will not be at their
best. They prefer still water and, although
the movement may be only gentle, it is not
advisable to risk losing choice plants. The
wild water lily (Nymphae alba) and the King
Cup (Nuphar luteum) otherwise the Yellow
Water Lily, are found commonly in slow-
moving streams in the country, and so are
quite suited to such a situation. Nuphar
advena, a North American relation of the
latter, is also at home in running water.
There is one cultivated lily, however, that has
a very hardy disposition and that may adapt
itself to the upper pool ; it is Brackleyi rosea,
a delightful plant with fragrant, rosy blooms
standing well above the water. Unfortunately this is an expensive variety, the price
being in the region of half a guinea.
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