Page:Popular Science Monthly Volume 26.djvu/412

398 of a gigantic helmet fronting eastward, to a height of 14,887 feet. Mount Whitney is thus entitled to rank as the Mont Blanc of its own continent. In order to reach it, a railway journey of 3,400 miles, from Pittsburg to San Francisco, and from San Francisco to Caliente, was a brief and easy preliminary. The real difficulty began with a march of 120 miles across the arid and glaring Inyo Desert, the thermometer standing at 110° in the shade (if shade there were to be found). Toward the end of July, 1881, the party reached the settlement of Lone Pine at the foot of the Sierras, where a camp of low-level observations was pitched (at a height, it is true, of close upon 4,000 feet), and the needful instruments were unpacked and adjusted. Close overhead, as it appeared, but in reality sixteen miles distant, towered the gaunt and rifted and seemingly inaccessible pinnacle which was the ultimate goal of their long journey. The illusion of nearness produced by the extraordinary transparency of the air was dispelled when, on examination with a telescope, what had worn the aspect of patches of moss, proved to be extensive forests.

The ascent of such a mountain with a train of mules, bearing a delicate and precious freight of scientific apparatus, was a perhaps unexampled enterprise. It was, however, accomplished without the occurrence, though at the frequent and imminent risk, of disaster, after a toilsome climb of seven or eight days through an unexplored and, to less resolute adventurers, impassable waste of rocks, gullies, and precipices. Finally a site was chosen for the upper station on a swampy ledge, 13,000 feet above the sea; and there, notwithstanding extreme discomforts from bitter cold, fierce sunshine, high winds, and, worst of all, "mountain-sickness," with its intolerable attendant debility, observations were determinedly carried on, in combination with those at Lone Pine, and others daily made on the highest crest of the mountain, until September 11th. They were well worth the cost. By their means a real extension was given to knowledge, and a satisfactory definiteness introduced into subjects previously involved in very wide uncertainty.

Contrary to the received opinion, it now appeared that the weight of atmospheric absorption falls upon the upper or blue end of the spectrum, and that the obstacles to the transmission of light-waves through the air diminish as their length increases, and their refrangibility consequently diminishes. A yellow tinge is thus imparted to the solar rays by the imperfectly transparent medium through which we see them. And, since the sun possesses an atmosphere of its own, exercising an unequal or "selective" absorption of the same character, it follows that, if both those dusky-red veils were withdrawn, the true color of the photosphere would show as a very