वेदों की प्राचीनता एवं काल-निर्णय / ओरायन (लोकमान्य बाल गंगाधर तिलक - खगोलीय वैदिक शोध)

34 THE ARCTIC HOME IN THE VEDAS.
uncertain, and this is especially the case when one has
to deal with long geological eras. The only reply made by Dr.
Croll to this criticism is that his figures were correctly worked
up from the values of the eccentricity according to the latest
correction of Mr. Stockwell.* This, however, is hardly a satisfac-
tory reply, inasmuch as Prof. Newcomb's objection refers not to
the correctness of the mathematical work, but to the impossibility
of correctly ascertaining the very data from which the values of
the eccentricity were obtained.
It was once supposed that the duration of each of Dr. Croll's
different periods admirably fitted in with the geological evidence,
and fully corroborated the estimates of time supposed to be
required for the extensive geographical changes which accompani-
ed the Glacial and Inter-Glacial periods. But geologists have now
begun to take a more sober view of these extravagant figures and
calculations. According to Croll's calculation there were three
periods of maximum eccentricity during the last three million years,
and there should, therefore, be three periods of glaciation corres-
ponding to these, each including several Glacial and Inter-Glacial
epochs. But there is no geological evidence of the existence of
such Glacial epochs in early geological eras, except, perhaps, in
the Permian and Carboniferous periods of the Palæozoic or the
Primary age. An attempt is made to meet this objection by
replying that though the eccentricity was greatest at one period
in the early geological eras, yet, as the geographical distribution of
land and water was then essentially different from what it was in
the Quaternary era, the high value of the eccentricity did not
then produce the climatic changes it did in the Pleistocene period.
This reply practically concedes that the high eccentricity of
the earth's orbit, combined with the occurrence of winter when
the earth is at aphelion, is not by itself sufficient to bring

• Climate and Cosmology, p. 39.