Curiosities of physical geography / by W. Wittich.

  • Wittich, Wilhelm, 1742-1848.
Date:
1845-1846
Catalogue details

Licence: Public Domain Mark

Credit: Curiosities of physical geography / by W. Wittich. Source: Wellcome Collection.

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    OF PHYSICAL GEOGRAPHY. Section I.—Snow-Mountains. The planet we inhabit is enveloped by air, which follows its motions and revolves with it about its axis. Air must herefore be considered as an integral part of the planet, md our globe to consist of air, land, and water. When lir is spoken of as a separate and distinct body, it is called atmosphere. It must not be supposed, however, :hat the ,whole space which intervenes between our planet and other celestial bodies is filled by air. If that vere the case, we should never have night, but that part )f the natural day which we call night would be distin- guished from that which we call day only by a fainter ight, resembling twilight, for twilight is but the reflec- ;ion of the sun’s light from the higher strata of the at- nosphere; consequently, if the whole space extending from our globe to the other heavenly bodies were filled ip by air, strata of air would be found over our heads, 30 situated as to lie beyond the shadow of our earth, md these strata would reflect the sun’s light all the time the sun was under the horizon, and would change the darkness of our nights into twilight. As this does aot take place, we are compelled to conclude that only the space near our earth is occupied by air, and that at some distance from it air ceases to exist. This leads us to the question, to what distance from the surface of the earth does the atmosphere extend ? We have no means to determine this point but by the duration of twilight. It is, however, very difficult to B