Page:Popular Science Monthly Volume 36.djvu/566

550 thick, misty, and murky, and the afternoon cold, raw, and disagreeable for a summer's day.

The observations made during night ascensions, or those which were continued into the night, on temperatures at different heights, gave results different from the theories previously held on the subject. An increase of the temperature with the height was noticed after sunset. The rate of decline of temperature with elevation when near the earth was subject to variation as the sky was clear or cloudy. From an elevation of three miles cirrus clouds were seen apparently as far above the observers as they seem when viewed from the earth, and that under such conditions that it was hard to believe that their presence was due to moisture. The audibility of sounds from the earth depended considerably on the amount of moisture in the air. The noise of a railway train could be heard in clouds at four miles high, but not when the clouds were far below. The discharge of a gun was heard at 10,000 feet; the barking of a dog at two miles; but the shouting of a multitude at not more than 4,000 feet. Many differences in the results of observations were supposed to depend upon atmospheric conditions, while these vary with the time of day and the season of the year; so that a great many observations would be required to determine the true laws. Having followed up one of the observations recorded above with a captive balloon and by other means, Mr. Glaisher declared to the Meteorological Society, in 1870, that the theory that the temperature is always lower at higher elevations is not true.

Some noteworthy mental impressions are recorded in Mr. Glaisher's descriptions of his ascents. Writing of his feelings at the height of 23,000 feet, and under the imminent necessity of descending at once, he was surprised "at the extraordinary power which a situation like this calls forth, when it is felt that a few moments only can be devoted to noting down all appearances and all circumstances at these extreme positions; and if not so rapidly gleaned they are lost forever. In such situations every appearance of the most trivial kind is noticed: the eye seems to become keener, the brain more active, and every sense increased in power to meet the necessities of the case; and afterward, when time has elapsed, it is wonderful how distinctly at any moment scenes so witnessed can be recalled and made to reappear mentally in all their details so vividly that, had I the power of the painter, I could reproduce them visibly to the eye upon the canvas." A fine description, of which we can quote only a part, is given of the scenery of the upper air: "Above the clouds the balloon occupies the center of a vast, hollow sphere, the lower portion of which is generally cut off by a horizontal plane. This section is in appearance a vast continent, often without intervals