In some of our smaller islands in the West-Indies, if I mistake not,
there are no springs or rivers; but the people are supplied with that
necessary element, water, merely by the dripping of some large tall
trees, which, standing in the bosom of a mountain, keep their heads
constantly enveloped with fogs and clouds, from which they
dispense their kindly never-ceasing moisture; and so render those
districts habitable by condensation alone.
Trees in leaf have such a vast proportion more of surface than
those that are naked, that, in theory, their condensations should
greatly exceed those that are stripped of their leaves; but, as the
former imbibe also a great quantity of moisture, it is difficult to say
which drip most: but this I know, that deciduous trees that are
entwined with much ivy seem to distil the greatest quantity. Ivy-
leaves are smooth, and thick, and cold, and therefore condense
very fast; and besides evergreens imbibe very little. These facts
may furnish the intelligent with hints concerning what trees they
should plant round small ponds that they would wish to be
perennial; and show them how advantageous some trees are in
preference to others.
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