Discussions on climate and cosmology / by James Croll.

  • James Croll
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Discussions on climate and cosmology / by James Croll. Source: Wellcome Collection.

    19/350 page 3
    Others, again, tried to explain the great changes of climate by supposing, with M. Poisson, that the earth during its past geological history may have passed through hotter and colder parts of space. This theory, however, was found to be so much opposed to known physical principles that it soon had to be abandoned. It has also been suggested that the changes of climate during geological ages might have resulted from alternations in the composition of the atmosphere, particularly in variations in the amount of carbonic acid gas possessed by the air. A theory was advanced many years ago by Professor H. Le Coq that the changes of climate may have been due to changes in the amount of the sun's heat. But this theory, like the above, appears to have gained but little acceptance. According to others, elevation of the land in the regions glaciated is assigned as the cause of that glaciation, and if the ice had been merely local, such an explanation might have sufficed. But we know the whole Northern Hemisphere, down to tolerably low latitudes, has been subjected in post-tertiary times to the rigour of an Arctic climate; so that, according to this theory, we must assume an upheaval of the entire hemisphere—an assumption too monstrous to be admitted, and as useless as absurd. At one time Lyell's theory of the relative distribu- tion of land and water was generally regarded by geologists as sufficient. It is, however, now generally admitted to be wholly insufficient to explain the now- known facts, and the conviction is becoming almost universal that we must refer the climatic changes in question to some cosmical cause. The theory of a change in the obliquity of the ecliptic has been appealed to. This theory for a time
    digitised image 1
    digitised image 2
    digitised image 3