"THE VOYAGE OF THE BEAGLE" - читать интересную книгу автора (Darwin Charles)

stream of clear water. It happened to be a grand feast-day,
and the village was full of people. On our return we overtook
a party of about twenty young black girls, dressed in
excellent taste; their black skins and snow-white linen being
set off by coloured turbans and large shawls. As soon as
we approached near, they suddenly all turned round, and
covering the path with their shawls, sung with great energy
a wild song, beating time with their hands upon their legs.
We threw them some vintems, which were received with
screams of laughter, and we left them redoubling the noise
of their song.

One morning the view was singularly clear; the distant
mountains being projected with the sharpest outline on a
heavy bank of dark blue clouds. Judging from the appearance,
and from similar cases in England, I supposed that the
air was saturated with moisture. The fact, however, turned
out quite the contrary. The hygrometer gave a difference
of 29.6 degs., between the temperature of the air, and the
point at which dew was precipitated. This difference was
nearly double that which I had observed on the previous
mornings. This unusual degree of atmospheric dryness was
accompanied by continual flashes of lightning. Is it not an
uncommon case, thus to find a remarkable degree of aerial
transparency with such a state of weather?

Generally the atmosphere is hazy; and this is caused by
the falling of impalpably fine dust, which was found to have
slightly injured the astronomical instruments. The morning
before we anchored at Porto Praya, I collected a little packet
of this brown-coloured fine dust, which appeared to have
been filtered from the wind by the gauze of the vane at the
masthead. Mr. Lyell has also given me four packets of dust
which fell on a vessel a few hundred miles northward of
these islands. Professor Ehrenberg [3] finds that this dust
consists in great part of infusoria with siliceous shields, and
of the siliceous tissue of plants. In five little packets which
I sent him, he has ascertained no less than sixty-seven
different organic forms! The infusoria, with the exception of
two marine species, are all inhabitants of fresh-water. I
have found no less than fifteen different accounts of dust
having fallen on vessels when far out in the Atlantic. From
the direction of the wind whenever it has fallen, and from
its having always fallen during those months when the harmattan
is known to raise clouds of dust high into the atmosphere,
we may feel sure that it all comes from Africa. It
is, however, a very singular fact, that, although Professor
Ehrenberg knows many species of infusoria peculiar to
Africa, he finds none of these in the dust which I sent him.
On the other hand, he finds in it two species which hitherto