The late Dr. Newmayr, of Vienna, a veteran physical geographer, in an able discussion of the climates of past ages, one of his last scientific papers, has fallen back on the hypothesis of a change in the position of the poles.[181] His failure to account for ancient climates by other causes evidently, however, depends on an inadequate conception of the effects of geographical changes, along with serious misconceptions as to the distribution of plants and the characters of vegetation at different periods. These points we shall have to discuss in subsequent pages. [181] _Society for Dissemination of Natural Science._ Vienna, January, 1889. In an address before the American Association, in 1886, Dr. Chamberlain, one of the ablest American authorities on the Glacial period, makes the following remarks as to the causes of the Pleistocene cold:-- "If we turn to the broader speculations respecting the origin of the Glacial epoch, we find our wealth little increased. We have on hand practically the same old stock of hypotheses, all badly damaged by the deluge of recent facts. The earlier theory of northern elevation has been rendered practically valueless; and the various astronomical hypotheses seem to be the worse for the increased knowledge of the distribution of the ancient ice sheet. Even the ingenious theory of Croll becomes increasingly unsatisfactory as the phenomena are developed into fuller appreciation. The more we consider the asymmetry of the ice distribution in latitude and longitude, and its disparity in elevation, the more difficult it becomes to explain the phenomena upon any astronomical basis. If we were at liberty to disregard the considerations forced upon us by physicists and astronomers, and permit ourselves simply to follow freely the apparent leadings of the phenomena, it appears at this hour as though we should be led upon an old and forbidden trail,--the hypothesis of a wandering pole. It is admitted that there is a _vera causa_ in elevations and depressions of the earth's crust, but it is held inadequate. It is admitted that the apparent changes of latitude shown by the determinations of European and American observatories are remarkable, but their trustworthiness is challenged. Were there no barriers against free hypotheses in this direction, glacial phenomena could apparently find adequate explanation; but debarred--as we doubtless should consider ourselves to be at present--from this resource, our hypotheses remain inharmonious with the facts, and the riddle remains unsolved." It should be observed here that the unsolved "riddle" is that of a continental ice sheet. This, as we have already seen, is probably insoluble in any way, but fortunately needs no solution, being merely imaginary. If we adopt a moderate view as to the actual conditions of the Pleistocene, the geographical theory will be found quite sufficient to account for the facts.