The shadow of Mont Blanc is discerned more easily at sunset. MM. Bravais and Martins, in one of their scientific ascents, noticed it under specially favorable circumstances, the shadow being thrown upon the snow-covered mountains, and gradually rising in the atmosphere until it reached a height of 1°, still remaining quite visible. The air above the cone of the shadow was tinted with that rosy purple which is seen, in a fine sunset, coloring the lofty peaks. "Imagine," says Bravais, "the other mountains also projecting, at the same moment, their shadows into the atmosphere, the lower parts dark and slightly greenish, and above each of these shadows the rosy surface, with the deeper rose of the belt which separates it from them; add to this the regular contour of the cones of the shadow, principally at the upper edge, and lastly, the laws of perspective causing all these lines to converge the one to the other toward the very summit of the shadow of Mont Blanc; that is to say, to the point of the sky where the shadows of our own selves were; and even then one will have but a faint idea of the richness of the meteorological phenomenon displayed before our eyes for a few instants. It seemed as though an invisible being was seated upon a throne surrounded by fire, and that angels with glittering wings were kneeling before him in adoration." Among the natural phenomena which now attract our attention, but fail to excite our surprise, there are some which possess the characteristics of a supernatural intervention. The names which they have received still bear witness to the terror which they once inspired; and even to-day, when science has stripped them of their marvellous origin, and explained the causes of their production, these phenomena have retained a part of their primitive importance, and are welcomed by the _savant_ with as much interest as when they were attributed to divine agency. Out of a large and very diverse number, I will first select the _Spectre of the Brocken_. The Brocken is the highest mountain in the picturesque Hartz chain, running through Hanover, being three hundred and thirty feet above the level of the sea.