Popular lectures and addresses / by William Thomson.

  • William Thomson, 1st Baron Kelvin
Date:
1889-
Catalogue details

Licence: Public Domain Mark

Credit: Popular lectures and addresses / by William Thomson. Source: Wellcome Collection.

    387/486 page 369
    ON THE SUN'S HEAT. A Friday evening Lecture delivered before the Royal In- stitution of Great Britain on January 21, 1887 : see also Good Words for March and April 1887.] FROM human history we know that for several thousand years the sun has been giving heat and light to the earth as at present, possibly with some considerable fluctuations, and possibly with some not very small progressive variation. The records of agriculture, and the natural history of plants and animals within the time of human history, abound with evidence that there has been no exceedingly great change in the intensity of the sun's heat and light within the last three thousand years; but for all that, there may have been variations of quite as much as 5 or 10 per cent., as we may judge by considering that the intensity of the solar radiation to the earth is 6\ per cent. B B
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