subject is one 'of vast, manifold, and rapidly-increasing importance,
and is but the beginning of a future great department of knowledge.'
Now that it has been published in a connected form, and the attention
of scientific observers directed to it, we may hope soon to hear of
corroborative evidence from all parts of the world. We may mention, as
bearing on the question, that sand-showers are not unfrequent in
China. Dr M'Gowan of Ningpo, in a communication to the Asiatic Society
of Bengal, states, that at the beginning of 1851, three showers
occurred within five weeks; the last, which commenced on the 26th
March, and continued four days, being the heaviest. The wind during
the time varied from north-east to north-west, the breeze interrupted
by occasional calms. No rain had fallen for six weeks; and though, as
the doctor observes, 'neither cloud, fog, nor mist obscured the
heavens, yet the sun and moon were scarcely visible; the orb of day
appeared as if viewed through a smoked glass, the whole sky presenting
a uniform rusty hue. At times, this sameness was disturbed, exhibiting
between the spectator and the sun the appearance of a water-spout,
owing to the gyratory motions of the impalpable mineral. The sand
penetrated the most secluded apartments; furniture wiped in the
morning, would be so covered with it in the afternoon, that one could
write on it legibly. In the streets, it was annoying--entering the
eyes, nostrils, and mouth, and grating under the teeth. My ophthalmic
patients generally suffered a relapse, and an unusual number of new
cases soon after presented themselves. Were such heavy sand-storms of
frequent occurrence, diseases of the visual organs would prevail to a
destructive extent.'

These showers sometimes spread over several provinces at once, and far
out to sea. The Chinese call them yellow-sand. Their source is the
great desert of Gobi, or Sand-Ocean, more than 2000 miles long, and