In 1886 he fell ill and was allowed to move to Saint Peterburg, and then was appointed head of an expedition exploring the Yana, Indigirka and Kolyma basins.
In 1886 he fell ill and was allowed to move to Saint Peterburg, where he joined the Peterburg's Science Academy. During that period he was appointed head of an expedition exploring the Yana, Indigirka and Kolyma basins.