The sample stage has X and Y mechanical movement. In addition, the top plate rotates for polarized light microscopy. The arrangement of control knobs on the same axis (as opposed to side-by-side) is known as the "Turrell's arrangement".
Stage top plate rotation.
This view shows the rack & pinion mechanism of the condenser focus (C) and stage "Y" movement. "A" is the worm screw for the stage lateral (X) movement.