Page:Notes on the State of Virginia (1853).djvu/62

ceeded gradually towards the torrid zone, that with this progress the animals of warm temperature retired towards the equator, and that in the present state of that progress the globe remains of sufficient warmth, for the elephant for instance, in the tropical regions, only to which therefore they have retired, as their last asylum, and where they must become extinct when the degree of warmth shall be reduced below that adapted to their constitution. How does it happen then that no elephants exist at present in the tropical regions of America, to which those of the Ohio must have retired, according to this theory? But if it be admitted that this obliquity has really decreased, and we adopt the highest rate of decrease yet pretended, that is, of one minute in a century, to transfer the Northern tropic to the Arctic circle, would carry the existence of these supposed elephants 250,000 years back; a period far beyond our conception of the duration of animal bones left exposed to the open air, as these are in many instances. Besides, though these regions would then be supposed within the tropics, yet their winters would have been too severe for the sensibility of the elephant. They would have had too but one day and one night in the year, a circumstance to which we have no reason to suppose the nature of the elephant fitted. However, it has been demonstrated, that if a variation of obliquity in the ecliptic takes place at all, it is vibratory, and never exceeds the limits of 9 degrees, which is not sufficient to bring these bones within the tropics. One of these hypotheses, or some other equally voluntary and inadmissible to cautious philosophy, must be adopted to support the opinion that these are the bones of the elephant. For my own part, I find it easier to believe that an animal may have existed, resembling the elephant in his tusks and general anatomy, while his nature was in other respects extremely different. From the 30th degree of South latitude to the 30th of North, are nearly the limits which Nature has fixed for the existence and multiplication of the elephant known to us. Proceeding thence northwardly to 36½ degrees, we enter those assigned to the mammoth. The further we advance North, the more their vestiges multiply as