It is not my intention here to analyse at length the characters and forms of clouds from the picturesque point of view. That has been most suggestively and eloquently attempted by Ruskin in various chapters of _Modern Painters_, which every mountain-lover should have read. One correction only of that fine description of mountain-clouds will I venture to make, the point being of some importance. "I believe," wrote Ruskin, "the true cumulus is never seen in a great mountain region, at least never associated with hills. It is always broken up and modified by them.... The quiet, thoroughly defined, infinitely divided and modelled pyramid never develops itself. It would be very grand if one ever saw a great mountain peak breaking through the domed shoulders of a true cumulus; but this I have never seen."
Whether it be true that cumulus cloud is never formed in the Alps I cannot say, my own notes not being accessible to me at this moment and my memory at fault; but this I can assert, that, in the heart of the great ranges, Himalayas and Andes, they frequently and magnificently occur. Never shall I forget the piled splendours, the divided and involved intricacies of rounded forms, the stupendous mass of the great towers of white cloud which I have often seen, with their level bases just upon or just above the summits of mountains more than 20,000 feet high, and their sharply outlined crests 15,000 or even 20,000 feet higher. Such clouds are only formed in warm uniformly ascending air currents, undisturbed by variable winds. They never form about peaks, but they form beside or above them. Often in Bolivia have I seen these great towers of mist rise with majestic deliberation behind the long white crest of the Cordillera Real, till they reduced the snowy peaks to mere pigmies at their feet. Then the afternoon wind would take them and bend them over the range like waves about to break. White island masses would sever themselves one by one and, passing the crest of the watershed, would drift away over the high plateau. If cumulus is formed in the Alpine region, its base would doubtless there also lie above the level of the snows, and the form of the clouds would not be realised by an observer in the mountain region. From Turin or Milan, gazing northward, immense masses of cumulus are often seen, but I have never yet been able to discover whether their bases rest on the snows or whether they merely lie above the foothills and lake-district.