The earth's surface, as far as the eye can reach, absolutely teems with the scattered fires of a watchful population, and exhibits a starry spectacle below, that rivals in brilliancy the lustre of the firmament above. A city looming up in the distant horizon gradually appears to blaze like a vast conflagration. On drawing near, every street is marked out by its particular line of fires; the forms and positions of the theatres, squares and markets are indicated by the presence of larger and more irregular accumulations of light, and the faint murmurs of a busy population still actively engaged in the pursuits of pleasure or the avocation of gain; all together combined form a picture, which, for beauty and effect, can not be conceived. Again, higher up, or when clouds intervene, the sky, at all times darker when viewed from an elevation, seems almost black with the intensity of night; while, by contrast, the stars redoubled in their lustre, shine like sparks of the whitest silver, scattered upon the jetty dome around. Nothing can exceed this density of night. Not a single object of terrestrial nature can anywhere be distinguished, and an unfathomable abyss of "darkness visible" encompasses one on every side. It seems like cleaving the way through an interminable mass of black marble, and a light lowered from these dizzy hights appears to absolutely melt its way down into the frozen bosom of the surrounding inkiness. The cold is here intense. VII.--ÆRIAL VOYAGES HEALTH PROMOTING. But while the charm of floating in the air is so fascinating these delightful ascensions will be even more beneficial in sanitary respects. Atmospheric pressure, exerting nearly 30,000 pounds upon a human being of full growth, has much to do with the mechanical functions of life. At a moderate elevation, one-tenth of this weight can be relieved, and at greater hights, even one-third, as balloon experiments have sufficiently proven. This pressure, then, diminishing upon the muscular system, allows it to expand. The lungs at once become more voluminous and breathing purer air; the freedom with which all the circulating fluids of the system are allowed to act in the rare atmosphere, intensely quicken the animal and mental faculties; the novelty of the voyage, and the most sublime grandeur opening to the eye and mind of the invalid; all assist to promote health, impart new life, inspire ideas and invigorate soul and body. VIII.--PARACHUTES.