There is no chain of mountains in which the shape of the valleys is more favorable to the formation of glaciers than the Alps. Contracted at their lower extremity, these valleys widen upward, spreading into deep, broad, trough-like depressions. Take, for instance, the valley of Hassli, which is not more than half a mile wide where you enter it above Meyringen; it opens gradually upward till, above the Grimsel, at the foot of the Finster-Aarhorn, it measures several miles across. These huge mountain-troughs form admirable cradles for the snow, which collects in immense quantities within them, and as it moves slowly down from the upper ranges is transformed into ice on its way, and compactly crowded into the narrower space below. At the lower extremity of the glacier the ice is pure blue and transparent, but as we ascend it appears less compact, more porous and granular, assuming gradually the character of snow, till in the higher regions the snow is as light, as shifting, as incoherent as the sand of the desert. A snowstorm on a mountain summit is very different from a snowstorm on the plain on account of the different degrees of moisture in the atmosphere. At great heights there is never dampness enough to allow the fine snow crystals to coalesce and form what are called snowflakes. I have even stood on the summit of the Jungfrau when a frozen cloud filled the air with ice-needles, while I could see the same cloud poring down sheets of rain upon Lauterbrunnen below. I remember this spectacle as one of the most impressive I have ever witnessed in my long experience of Alpine scenery. The air immediately about me seemed filled with rainbow dust, for the ice-needles glittered with a thousand hues under the decomposition of light upon them, while the dark storm in the valley below offered a strange contrast to the brilliancy of the upper region in which I stood. One wonders where even so much vapor as may be transformed into the finest snow should come from at such heights. But the warm winds creeping up the sides of the valley, the walls of which become heated during the middle of the day, come laden with moisture which is changed to a dry snow like dust as soon as it comes into contact with the intense cold above.