It was in vain to think of flying; the swiftest horse or the fasted sailing ship could be of no use to carry us out of this danger; and the full persuasion of this rivetted me as if to the spot where I stood.” At another time he saw them in much greater number, but of smaller size. They began immediately after sunrise, like a thick wood, and almost darkened the sun. His rays darting through them gave them the appearance of pillars of fire. They now approached to the distance of two miles from our travellers. At another time they appeared beautifully spangled with stars. in Darwin’s Botanic Garden we find a reason assigned for the appearance of these whirlwinds; viz. the impulse of the wind on a long ledge of broken rocks which bound the desert. By these the currents of air which struck their sides were bent and were thus like eddies in a stream of water which falls against oblique obstacles. In the same work we have the following poetical description of them: * _N. B._ In these sandy deserts, where it never rains, there are no clouds. “Now o’er their heads the whizzing whirlwinds breathe, And the live desert pants and heaves beneath; Ting’d by the crimson sun, vast columns rise Of eddying sands, and war amid the skies, In red arcades the billowy plains surround, And whirling turrets stalk along the ground.” Whether the simoom is always preceded by these whirlwinds we know not; but Mr. Bruce mentions an extreme redness of the air, pointed out by his attendant Idris, as the sure presage. His advice was, that all of them, upon the approach of the pernicious blast, should fall upon their faces, with their mouths on the earth, and hold their breath as long as possible, so that they might not inhale the deadly vapour. They soon had occasion to follow this advice; for next day Idris called out to them to fall upon their faces, for the simoom was coming. “I saw (says Mr. Bruce) from the S. E. a haze coming, in colour like the purple part of the rainbow, but not so compressed or thick. It did not occupy twenty yards in breadth, and was about twelve feet high from the ground. It was a kind of blush upon the air, and it moved very rapidly; for I could scarce turn to fall upon the ground, with my face to the northward, when I felt the heat of its current plainly upon my face. We all lay flat on the ground, as if dead, till Idris told us it was blown over. The meteor, or purple haze, which I saw, was indeed passed; but the light air that still blew was of heat sufficient to threaten suffocation. For my part, I felt distinctly in my breast that I had imbibed a part of it; nor was I free of an asthmatic sensation till I had been some months in Italy, at the baths of Poretta, near two years afterwards.” It continued to blow for some time, and in such a manner as entirely to