CENTRAL ASIAN EXPLORATION 15 
these problems can be brought within measurable distance 
o solution. During the last twenty-five years only four 
geo ogists of standing have devoted any attention to the 
^gion of the Kwen-lun system, namely, Stoliczka, Von 
ichthofen, Loczy, and Bogdanovitch. 
But vast gaps still divide the regions which they 
ave severally investigated. It is my intention during 
IS projected journey to contribute as far as lies 
in my power to the filling in of these gaps, where 
every observation, every contour - line, is of the utmost 
value. 
Another problem of intense interest is the Lop-nor 
question, which was raised by Baron von Richthofen. 
will mention here some of the points set forth in his 
^tic e entitled “ Bemerkungen zu den Ergebnissen von 
erst-lieutenant Prjewalski’s Reise nach dem Lop -noor 
Altyn-tagh ” ( F ?rhandhmgen der Ges. fiir Erdhmde, 
■’ ^878, pp. 121 et seqq.). 
Marco Polo was the first to make the Lop desert known 
n uropeans, and on D’Anville’s map of Asia Lop-nor 
Its rivers is found for the first time, though in latitude 
42 20 N. Shortly before Przhevalsky’s journey the lake 
Was supposed to be situated in an enormous basin, and at 
greater distance to the south than to the north of the 
luountains which bounded it. Przhevalsky, however, found 
3 -t the lake lay much farther south than was supposed 
^rom the maps and Chinese accounts, and the result of 
IS and his other expeditions was, that the maps of the 
interior of Asia came to present quite a different appear- 
from what they had heretofore. The territory 
Ween Korla and Altyn-tagh was quite unknown ; as 
Was also the fact, that the lower Tarim ran for such a 
^ng distance in a south-easterly direction. The discovery 
n the Altyn-tagh possessed equal importance as a con- 
1 ution to the knowledge of the physical geography of 
of comprehension of the position and direction 
th nncient trading-routes. It now became clear why 
^ ancient silk caravans from China to the West kept so 
^ur the .south of Lop-nor, necessitating their passing 
