Cataracts of the Orinoco.

—A foaming surfaceof four miles in length presents itself at once to theeye: iron-black masses of rock resembling ruins andbattlemented towers rise frowning from the waters.Rocks and islands are adorned with the luxuriant ve-getation of the tropical forest; a perpetual misthovers over the waters, and the summits of the loftypalms pierce through the cloud of spray and vapour.When the rays of the glowing evening sun are re-fracted in these humid exhalations a magic opticaleffect begins. Coloured bows shine, vanish, and re-appear; and the ethereal image is swayed to andfro by the breath of the sportive breeze. During thelong rainy season the streaming waters bringdown islands of vegetable mould, and thus thenaked rocks are studded with bright flower-beds adorned with Melastomas and Droseras, and withsmall silver-leaved mimosas and ferns. These spotsrecall to the recollection of the European those blocksof granite decked with flowers which rise solitaryamidst the glaciers of Savoy, and are called by thedwellers in the Alps “Jardins,” or “Courtills.” Inthe blue distance the eye rests on the mountain chainof Cunavami, a long extended ridge which terminatesabruptly in a truncated cone. We saw the latter(Calitamini in its Indian name) glowing at sunset asif in roseate flames. This appearance returns daily:no one has ever been near the mountain todetect the precise cause of this brightness, whichmay perhaps proceed from a reflecting surfaceproduced by the decomposition of talc or micaslate. During the five days which we passed in theneighbourhood of the cataracts, it was striking to hearthe thunder of the rushing torrents sound three timeslouder by night than by day. In all European water-falls the same phenomenon is remarked. What canbe its cause in a wilderness where there is nothing tointerrupt the repose of nature! Perhaps the currentsof heated ascending air, by causing irregular densityin the elastic medium, impede the propagation of soundduring the day, by the disturbance they may occasionin the waves of sound; whereas during the nocturnalcooling of the earth’s surface the upward currentscease.— Humboldt’s Aspects of Nature.