Meteorological observations and essays / By John Dalton.

  • John Dalton
Date:
1834
Catalogue details

Licence: Public Domain Mark

Credit: Meteorological observations and essays / By John Dalton. Source: Wellcome Collection.

    101/280 (page 75)
    vital or dephlogisticated air.—Whether the superior regions of the atmosphere consist in like manner of various elastic fluids, or whether the fluids are the same or different from these below, cannot, from the nature of the case, be determined experi- mentally. The figure of the exterior surface of the atmos- phere would, from the principles of gravitation, be similar to that of the earth, or of an oblate spheroid; or, its height and quantity of matter about the equa- tor, would be something greater than at the poles | to preserve an equilibrium every where, owing to the centrifugal force, which is greatest at the equa- tor. The density of the atmosphere, supposing it of a uniform temperature, and alike constituted every where, would decrease in ascending, in a geometrical progression: thus, if the density at one mile high was 1, and that at four miles high +; then that at seven miles high would be i, at ten miles high g, &.—I say these circumstances would be, were it not for the sun, or the principle of heat which it seems to produce; but by means of the unequal diffusion of this principle, the cir- cumstances are very materially different. The mean annual temperature of the air, at the earth’s surface, decreases in going from the equator to the poles. Mr. Kirwan* states the mean an- nual heat at the equator at 84°, and that at the pole at 31°. Moreover, the temperature of the air. over any place, in clear, serene weather, decreases * Estimate of the Temperature of different Latitudes.