Climate : an inquiry into the causes of its differences, and into its influence on vegetable life : comprising the substance of four lectures delivered before the Natural History Society, at the Museum, Torquay, in February, 1863 / by C. Daubeny.

  • Daubeny, Charles Giles Bridle, 1795-1867.
Date:
1863
Catalogue details

Licence: Public Domain Mark

Credit: Climate : an inquiry into the causes of its differences, and into its influence on vegetable life : comprising the substance of four lectures delivered before the Natural History Society, at the Museum, Torquay, in February, 1863 / by C. Daubeny. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    from the calculations of Professor Dove, who is regarded as the highest authority on the subject of temperature, that if the annual mean at the equator be reckoned at 79°, there would be no difference, but rather a slight increase, in the heat of the globe in all the latitudes within 10 de- grees of the line; after which, in the 20th parallel, the temperature would sink to 76<^; in the 30th, to 68«; in the 40th, to 56«: in the 50th, to 41«; in the 60th, to 30«; in the 70th, to 17°; and that it would stand nearly at zero in the 80th, the highest latitude yet attained by man, from which point to the poles there would probably be found little or no deviation as to temperature. Thus the decrement of heat from the equator up to the 20th parallel does not exceed 3° of Fahr.; between 20° and 30°, and 30° and 40°, it goes on pretty uniformly at the rate of 8° of Fahr. for 10° of latitude; it then progresses in an in- creasing ratio from 40° to 50°, namely, about 15° of tem- perature for 10° of latitude; diminishes again between 50° and 60°, between which parallels the rate of decrease is 11° of temperature for 10° of latitude; rises again to 13° between 60° and 70°, where the difference amounts to 13°; and attains its highest rate of diminution between 70° and 80°, where it is as much as 17°. The difference between the actual rate of diminution in temperature according to latitude, and that which would prevail if the earth had been a flat surface with the sun stationed exactly perpendicularly to the equator, may be exhibited in a tabular form by a curved line describing the rate of decrease in temperature in different latitudes. See Table opposite. It is, however, evident, that although the figures I have given represent the heating effect produced by the direct solar influence upon each portion of the globe, so far as it is due to latitude, so many concurrent causes contribute to the aggregate effect, that few spots exactly accord with this theoretical estimate, some falling short of it, and a still greater number exceeding the number assigned. But before entering upon this subject it will be well to