In this lecture I had submitted the most important data on which my plan was founded; but in the following years I continued to study the conditions of the northern waters, and received ever fresh proofs that my surmise of a drift right across the Polar Sea was correct. In a lecture delivered before the Geographical Society in Christiania, on September 28, 1892, I alluded to some of these inquiries. [10] I laid stress on the fact that on considering the thickness and extent of the drift-ice in the seas on both sides of the Pole, one cannot but be struck by the fact that while the ice on the Asiatic side, north of the Siberian coast, is comparatively thin (the ice in which the Jeannette drifted was, as a rule, not more than from 7 to 10 feet thick), that on the other side, which comes drifting from the north in the sea between Greenland and Spitzbergen, is remarkably massive, and this, notwithstanding that the sea north of Siberia is one of the coldest tracts on the earth. This, I suggested, could be explained only on the assumption that the ice is constantly drifting from the Siberian coast, and that, while passing through the unknown and cold sea there is time for it to attain its enormous thickness, partly by freezing, partly by the constant packing that takes place as the floes screw themselves together. I further mentioned in the same lecture that the mud found on this drift-ice seemed to point to a Siberian origin. I did not at the time attach great importance to this fact, but on a further examination of the deposits I had collected during my Greenland expedition it appeared that it could scarcely come from anywhere else but Siberia. On investigating its mineralogical composition, Dr. Törnebohm, of Stockholm, came to the conclusion that the greater part of it must be Siberian river mud. He found about twenty different minerals in it. "This quantity of dissimilar constituent mineral parts appears to me," he says, "to point to the fact that they take their origin from a very extensive tract of land, and one's thoughts naturally turn to Siberia." Moreover, more than half of this mud deposit consisted of humus, or boggy soil. More interesting, however, than the actual mud deposit were the diatoms found in it, which were examined by Professor Cleve, of Upsala, who says: "These diatoms are decidedly marine (i.e., take their origin from salt-water), with some few fresh-water forms which the wind has carried from land. The diatomous flora in this dust is quite peculiar, and unlike what I have found in many thousands of other specimens, with one exception, with which it shows the most complete conformity--namely, a specimen which was collected by Kellman during the Vega expedition on an ice-floe off Cape Wankarem, near Bering Strait. Species and varieties were perfectly identical in both specimens." Cleve was able to distinguish sixteen species of diatoms. All these appear also in the dust from Cape Wankarem,