the air, as might be expected, is very much greater than in clear states; and above the clouds, at the same height, there are very different degrees in the different experiments.

The laws of moisture are indicated by these experiments, as found by taking the means of the numbers under the same state of the sky, and are as follows:

With an overcast sky, the degree of
humidity on the earth was

of }

77 from 6 experiments.

The laws of moisture here indicated are-an almost uniform state of humidity of the air to the height of 3000 feet, viz. 77; then a sudden increase to 80 in the next 1000 feet, and to 83 by 5000 feet, which slightly decreased to 82 by 6000 feet.

When the sky was partially clear, the degree of humidity

The laws of moisture here indicate a humidity on the ground, with a partially clear sky, less by 15 than in cloudy skies, increasing to 77 by 3000 feet, then nearly constant to 5000 feet, when the humidity abruptly decreased to 69, and then nearly evenly at the rate of 5 in 1000 feet, till at 9000 and 10,000 feet it is 52; the degree then constantly decreases, till at heights exceeding 25,000 feet the degree of humidity is reduced to less than 10; and it would seem that at the higher elevations there is an almost entire absence of water.

These seem to be the general laws; but this regular diminution is evidently often interrupted, and strata of moist air exist at different elevations even up to 20,000 feet, and these may be of considerable thickness.

§ 7. COMPARISON OF THE TEMPERATURE OF THE DEW-POINT, AS DETERMINED BY

DIFFERENT INSTRUMENTS.

Every simultaneous or nearly simultaneous determination of the dewpoint by the different instruments or methods was copied out, and then all those determinations between every 1000 feet of elevation were collected together, and in this way the first five columns of the following Table were formed. The numbers in the last six columns were formed by taking the differences between the temperatures of the respective dew-points in the same horizontal line, or those taken at about the same height and elevation.

TABLE IX.-Showing the Temperature of the Dew-point, as determined at about the same height by different instruments and methods, and comparison of the results together.

490 495 49'9 490 45'5-04 +0.5 +40 +0°9 +44 +35

8543

887 59'9

58.5

+14