国立情報学研究所 - ディジタル・シルクロード・プロジェクト
『東洋文庫所蔵』貴重書デジタルアーカイブ

is too short to make it possible for us to use its records for proving climatic changes.
The most that can be shown is periodical changes between moist and less moist
epochs, as in the case of the Caspian. If now 2,200 years is too short a space of
time for Baluchistan and Southern Persia, much cannot be expected from the meagre
records embracing 200 years which exist for the Manasarovar and Rakas-tal. But even
within this short space of time the two lakes afford us not only a possibility, but
also an excellent opportunity to prove the existence of changes in the amount of
precipitation with a rather short periodicity. And for readings of that sort the lakes
are, as I said before, a most delicate and sensitive instrument. Even here there are
two different periods. The one, the maxima of which are indicated by the outflow
from the Rakas-tal, is of a higher order than the one where the maxima are indicated
by the effluence through the channel from the Manasarovar. For this channel may
be in function without any water escaping from the Rakas-tal. Thus several Ma-
nasarovar maxima may occur between two Rakas-tal maxima.
Above and beyond the Rakas-tal period it would be impossible to tell how
many still higher orders exist. But above all there stands the great curve of desicca-
tion going on during the whole post-glacial, or post-pluvial period. It proceeds from
a maximum towards a minimum. All observed phenomena seem to prove that it
still, in our time, proceeds in the same direction. When it has once reached its
minimum it will probably again return towards a new maximum.
The oldest records we possess and which may be used for researches in the
hydrographical situation, are those which have been saved by Father TIEFFENTHALER
and Father GAUBIL.¹ Of them BONIN says: »En résumé, ce qui ressort de l'ensemble
des croquis qui viennent d'être décrits, c'est la constatation sur les premiers,² qui
remonteraient à la fin du XVIe siècle, de l'existence d'un émissaire du Manasarowar
se dirigeant au Nord-Ouest, et sur le dernier,³ qui peut être postérieur, d'une jonc-
tion très apparente entre ce lac et le Rakas-tal.»⁴ Bonin does not mention the most
important conclusion that can be drawn from both maps, namely, that the Satlej also
went out from the Rakas-tal. It is less interesting that a communication existed
between both lakes, for such was also the case in 1911.
Bonin believes that Tieffenthaler's map of the lakes is from the end of the
16th century, as the Persian legends indicate that the maps date from some of the
Great Moguls, probably Emperor Akbar. Thus the map should be from about 1590
and the years of Tifferenthaler's own journeys should not have anything to do with it.
It seems, however, that Tieffenthaler has now two sources, the map with the Persian
text, and the information he got from a Hindu, who had wandered round the Ma-
nasarovar himself. Thus the verbal information should date from the year of the