Note A — THE STORM-CLOUD OF THE NINETEENTH CENTURY.

"But both Saussure and I ought to have known,—we did know, but did not think of it,—that the covering or cap-cloud forms on hot summits as well as cold ones;—that the red and bare rocks of Mont Pilate, hotter, certainly, after a day's sunshine than the cold storm-wind which sweeps to them from the Alps, nevertheless have been renowned for their helmet of cloud, ever since the Romans watched the cloven summit, gray against the south, from the ramparts of Vindonissa, giving it the name from which the good Catholics of Lucerne have warped out their favorite piece of terrific sacred biography. And both my master and I should also have reflected that if our theory about its formation had been generally true, the helmet cloud ought to form on every cold summit, at the approach of rain, in approximating proportions to the bulk of the glaciers; which is so far from being the case that not only (A) the cap-cloud may often be seen on lower summits of grass or rock, while the higher ones are splendidly clear (which may be accounted for by supposing the wind containing the moisture not to have risen so high); but (B) the cap-cloud always shows a preference for hills of a conical form, such as the Mole or Niesen, which can have very little power in chilling the air, even supposing they were cold themselves; while it will entirely refuse to form huge masses of mountain, which, supposing them of chilly temperament, must have discomforted the atmosphere in their neighborhood for leagues."