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C. J. Cornish - The Naturalist on the Thames
Clement Reid, F.R.S., has added to the "Selborne" notes his own experiences of the best sites for dew
ponds. They should, he thinks, be sheltered on the south-west by an overhanging tree. In those he is
acquainted with the tree is often only a stunted, ivy-covered thorn or oak, or a bush of holly, or else the
southern bank is high enough to give shadow. "When one of these ponds is examined in the middle of a
hot summer's day," he adds, "it would appear that the few inches of water in it could only last a week.
But in early morning, or towards evening, or whenever a sea-mist drifts in, there is a continuous drip
from the smooth leaves of the overhanging tree. There appears also to be a considerable amount of
condensation on the surface of the water itself, though the roads may be quite dry and dusty. In fact,
whenever there is dew on the grass the pond is receiving moisture."
Though this is evidently the case, no one has explained how it comes about that the pond surface receives
so very much more moisture than the grass. The heaviest dew or fog would not deposit an inch, or even
two inches, of water over an area of grass equal to that of the pond. None of the current theories of dew
deposits quite explain this very interesting question. Two lines of inquiry seem to be suggested, which
might be pursued side by side. These are the quantities distilled or condensed on the ponds, and the
means by which it is done; and secondly, the kind of tree which, in Gilbert White's phrase, forms the best
"alembic" for distilling water from fog at all times of the year. It seems certain that the tree is an
important piece of machinery in aid of such ponds, though many remain well supplied without one.
[1] Thomas Elliot, who for some twenty years was shepherd and general manager for one of my father's
tenants at Childrey.
[2] Full details of the cost and method of making dew ponds, as well as other information about them, are
contained in the prize essay of the late Rev. J. Clutterbuck, Rector of Long Wittenham, in the Journal of
the Royal Agricultural Society. Vol. I., Sec.S. Part 2.
[3] In the Isle of Wight, on Brightstone Downs, about 400 feet above the sea, is a dew pond with a
concrete bottom, which has never run dry for thirty years.
POISONOUS PLANTS
A friend informs me that he has found a quantity of woad growing on the Chilterns above the Thame,
enough to stain blue a whole tribe of ancient Britons, and also that on a wall by the roadside between
Reading and Pangbourne he discovered several plants of the deadly nightshade, or "dwale." This word is
said to be derived from Old French deuil, mourning; but its present form looks very English. The
only cases of plant poisoning now common among grown-up people are those caused by mistaking fungi
for mushrooms, or by making rash experiments in cooking the former, of which Gerard quaintly says:
"Beware of licking honey among the thorns, lest the sweetness of the one do not countervail the
sharpness and pricking of the other." But with such a list of toxic plants as our flora can show there is
always danger from certain species whose properties are quite unknown to ordinary mortals. Are they
equally unknown to the herbalists and that mysterious trade-union of country-women and collectors of
herbs by the roadside who deal with them? Probably the trade in poisons not used for serious purposes,
but for what used in some parts of England to be called "giving a dose," a punishment for unfaithful,
unkind, or drunken husbands, still exists as it did some forty years ago. The collectors of medicinal plants
cut from the roadside and rubbish heaps, plants whose "operations" for good are quite well known, and
have been handed down by tradition for centuries, cannot be absolutely ignorant of the other side of the
picture, the toxic properties which other plants, or sometimes even the same plants, contain. Foxglove,
for instance, from which digitalis used as a medicine is extracted, is a good example of these
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