[53] Air nearly saturated with vapour is lighter than air relatively dry; and hence it may happen that, when a current of moist air meets one relatively dry, it will flow over the latter if they are nearly at the same temperature, but if the drier current be much warmer, it may flow beneath it.
[54] On this subject see Handbuch der Klimatologie, by Julius Hann, pp. 141, et seq. See also Tables I. and II. in a report on thermometric observations in the Alps, by J. Ball, in Reports of the British Association for the Advancement of Science for 1862, pp. 366–368.
[55] See “Die Barometrischen Höhenmessungen und ihre Bedeutung für die Physik der Atmosphäre,” Leipzig, 1870, by R. Rühlmann.
[56] I use the term “eccentricity” in the popular sense, to express the distance of the focus from the centre of the ellipse.
[57] Viewed in the light of Mr. Langley’s recent researches on solar radiation, all these numerical determinations are probably far from the truth; but the errors do not much affect the present argument.
[58] The observations at Stanley Harbour, which are those adopted by Dr. Hann (Klimatologie, p. 697), show temperatures notably lower than those recorded for a place in the islands lying farther south, which are given in the Zeitschrift der Œsterreichischen Gesellschaft für Meteorologie, vol. v. p. 369. The mean of the two is probably nearly correct.
[59] These figures are derived from the tables given in the Anales de la Oficina Meteorologica Argentina, by B. Gould, vol. iii. The figures show a considerable amount of annual variation. The monthly means of the six months from February to July, 1879, exceed those of the same period in 1878 by more than 2° Fahr.
Transcriber’s Notes
Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.
Simple typographical errors were corrected; occasional unbalanced quotation marks retained.