‘The appearance of the upper cascade, in the middle of winter, is very interesting. The rock over which the stream descends, projects in such a manner, that the icicles, which form in that season, meet with no interruption in their descent towards the base of the fall. The water, which strikes the rocks below, begins to congeal and rise (between the column of water and the rock) towards the icicles above. These project towards the base, increasing in magnitude from day to day, while the column from below is greatly enlarged by the water and the spray, which, immediately congealing, in a short time surround the stream. A column of ice, resembling a rude cone, of between two and three hundred feet, is thus formed, through the centre of which the stream pours its current, dwindled, by the congelation of its waters, to one tenth its common size. When illumined by the rays of the sun, it presents a transparent column glowing with brilliancy, reflecting and refracting its rays in such a manner as to present all the colors of the prism. It remains some weeks, a striking example of the power of hoary frost, when, partly dissolved by the genial warmth of spring, it falls, scattering its thousand fragments on the rocks around it.’ GENERAL REMARKS ON CATARACTS AND CASCADES. Rivers which descend from primitive mountains into the secondary lands often form _cascades and cataracts_. Such are the cataracts of the Nile, of the Ganges, and some other great rivers, which, according to Desmarets, evidently mark the limits of the ancient land. Cataracts are also formed by lakes, and of this description are the Falls of Niagara; but the most picturesque falls are those of rapid rivers, bordered by trees and precipitous rocks. Sometimes we see a body of water, which, before it arrives at the bottom, is broken and dissipated into showers, like the Staubach; sometimes it forms a watery arch, projected from a rampart of rock, under which the traveller may pass dry shod, as the Falling Spring of Virginia; in one place, in a granite district, we see the Trolhetta, and the Rhine not far from its source, urge on their foaming billows amongst the pointed rocks; in another, amidst lands of calcareous formation, we see the Czettina, and the Kerka, rolling down from terrace to terrace, and presenting sometimes a sheet and sometimes a wall of water. Some magnificent cascades have been formed, at least in part, by the hands of man: the cascades of Velino, near Terni, have been attributed to Pope Clement VIII.; other cataracts, like those of Tunguska in Siberia, have gradually lost their elevation by the wearing away of the rocks, and have now only a rapid descent. The Falls of Staubach are the highest ever known, being nine hundred feet according to trigonometrical measurement. CHAPTER VI.――LAKES.