From the auction listing description:
He lies on his stomach upon the table which swivels as he makes a scissor movement with his legs while nodding his head. He then raises his legs. The table swivels again. He raises his head, lifts his stomach off the table and arches his back in an amazing contortionist manner, with his legs raised high. He repeats the scissor movement before lowering himself back onto the table and scissoring his legs once more in the horizontal position.
An amazing piece with a strong and prestigious lineage.
Here is the full auction listing for The Serpent Man, L'Homme Serpent automaton.