Carried upward passively in a balloon, without effort, men have risen higher than the highest mountains. Mr. Coxwell and Mr. Glaisher in their celebrated aerial voyage of 1862 are believed to have mounted seven miles above the sea. No little peril and suffering were involved, alike from the extreme thinness of the air, and from the bitter cold. The voyagers suffered from severe “sea-sickness,” though not from bleeding of the nose or singing in the ears, popularly expected on such occasions. They had enough to bear without these additions. Mr. Glaisher held manfully to his task, observing and noting down the state of the atmosphere minute by minute, despite sickness, brain-pressure, violent headache, and a pulse at 108 per minute, all due to the rarity of the air. In those lofty regions of the air-ocean no living creatures exist. The voyagers passed through boundless silent solitudes--silent except for the hurried beating of their own hearts, the sound of their own panting breath, the sharp ticking of their watches, and the “clang of the valve door.” On leaving earth the thermometer stood at 59°. Soon afterward the balloon passed through masses of cloud, thousands of feet in depth, then came out into dazzling sunshine, with deep-blue sky above and countless mountain masses of billowy cloud below. As they rose, they released at intervals a captive pigeon. One set free at a height of nearly five miles “fell downward like a stone.” Of two others taken higher, one died of the cold and the other was stupefied. When they reached five miles above the sea, the temperature was below zero. Still upward, further upward, rose the resolute pair. Then blinding darkness and insensibility seized Mr. Glaisher. Had he been alone, he could never have revived. With no one to open the valve, the balloon must have carried him onward into yet higher and deathlier regions, where for lack of air he would have perished. Even then Mr. Coxwell did not at once give in; but he was strictly on the watch. At the seven miles’ level, a tremendous height, he too felt signs of failing consciousness. In a few minutes more all would have been over with them both, and at last he yielded. It was indeed time that he should. His hands were powerless to act, but he seized the valve rope in his teeth and pulled. The gas rushed out; the balloon steadily sank. Both lives were saved, and a mighty feat had been accomplished. Yes, a mighty feat, and a tremendous height--in consideration of human powers! Seven miles high would seem to be the outside limit at which animals generally can exist for even a short time. Birds may be to some extent an exception. Certain birds are believed to soar occasionally two or three miles higher still.