Note 34 — STEPPES AND DESERTS.

p. 17.—“Conical-shaped clouds.”

The singular phenomenon of these “sand spouts,”—something analogous to which may occasionally be seen on a small scale in Europe where four roads meet,—is particularly characteristic of the Peruvian Sand Desert between Amotape and Coquimbo. Such a dense cloud of sand or dust may prove dangerous to the traveller who does not cautiously avoid its approach. It is also worthy of notice that these partial conflicting currents of air only arise when the air generally is perfectly calm. The aerial ocean resembles the sea in this respect, for in the latter also the small currents which are often heard to ripple audibly, (filets de courant), are only perceptible in a dead calm (calme plat).