Adolph von Menzel (1815-1905) - Hombre observando

There are several thousand drawings by Adolph von Menzel (1815-1905).
One of them is the drawing of the man looking up: "omhoog kijkende man".
See p. 1213 of "Adolph von Menzel, Das graphische Werk in zwei Bänden" Vol 2.
In the early 1880s, he made many of these kinds of drawings.
This is a crayon drawing of the same man looking up, with the hand studies. From the same period.
On the back, there is another failed sketch of a girl’s head.