Painting Semenov-Tian-Shansky

[Spielman]

Dear members of the forum, ask for help in the attribution.
There is a picture of the Semenov -Tian- Shansky , " Quiet time ... twilight and the light " (signed at bottom left ). Right at the bottom of the autograph and the date - 1913 Pastel on paper . 47h69 size , 5 cm
It is theoretically possible that he drew and wrote something in my old age , he died unnecessarily only in 1914 that I am the light of science known as a geographer and biologist, but as I do about the artist about his abilities have not heard .
Maybe someone has seen of Tian-Shansky , or have someone to compare ?