Page:Popular Science Monthly Volume 11.djvu/331

Rh (summit of Vesuvius), 56 centimetres at 2,432 metres (pass of the Great St. Bernard), 46 at 3,998 metres (Mont Pelvoux), 39 at 5,920 metres (the height of the highest pass of the Himalaya is 5,835 metres). The greatest height attained by man was reached by Glaisher in a balloon—8,840 metres, pressure 24. 76 centimetres—and by the brothers Schlagintweit on foot, in the Himalaya, 6,882 metres, pressure 32 centimetres. The highest mountain on the globe, Gaurisankar, measures precisely 8,840 metres—the elevation at which Mr. Glaisher fell fainting to the floor of his car.

Such modifications of pressure cannot be endured with impunity by the human organism. Though life in moderately elevated regions, as the Jura and Auvergne, seems to be so beneficial to those who dwell there constantly, that multitudes come thither from afar in pursuit of health; and though in regions situated at a greater altitude, as the admirable plateau on which the city of Mexico stands, the sum of the climatic conditions seems to oifer hygienic advantages: still all are agreed that at very great elevations there always supervene, with more or less intensity according to persons and circumstances, certain characteristic perturbations and discomforts described by travelers in the Alps, the Pyrenees, the Andes, and the Himalaya.

These are, first, a sense of fatigue out of proportion to the amount of walking or of work performed. The legs appear to become leaden, and one feels a weakness in the knees. Then the breath becomes short, diflicult, labored; the pulse is quickened; the heart-beats occur isolatedly, and reverberate in the head. Next come singing in the ears, dimness of sight, and vertigo. The general sense of malaise, the feebleness, become such that the traveler must rest, else he will fall to the ground. Simultaneously there occur other symptoms having their seat in the digestive organs, such as nausea and vomiting. These various symptoms, taken together, constitute mountain-sickness (mal des montagnes), which bears a resemblance to sea-sickness.

When they first appear, a few moments' rest suftices to banish them; this instantaneous restoration of strength and vigor sharply distinguishes mountain-sickness from ordinary fatigue. But at greater elevations, where graver symptoms appear, such as bleeding from the nose or from the lungs, repose cannot bring back the condition of perfect health, though it always afibrds some relief. Travelers agree in saying that a person on horseback suffers far less than one on foot. On the high plains of the northern Himalaya, a rather brisk pace in walking, the ascent of a hill however low, the carrying of a moderately heavy load, sufiice to exhaust one's strength, to cause him to faint, and in some cases even to produce death.

This is the reason why aëronauts are attacked much later than those who ascend the mountain-side. Ever since the day when Montgolfier, realizing the immemorial aspirations of the human race, gave to man the means of overcoming the gravity which ties him to the