PHILADELPHIA — What makes an automaton tick?

For the one on display at the Franklin Institute here, the answer is: a couple of hefty spring motors. The automaton, a mechanized doll built more than two centuries ago by the Swiss watchmaker Henri Maillardet, uses the power from the wind-up motors, carried through linkages to its right arm, to write and draw.

But it is what’s between the motors and the arm that makes the two-foot-high Maillardet automaton seem like more than a machine. A stack of rotating brass cams precisely control the arm movements. As steel levers follow hills and valleys cut into the edges of the rotating disks, the arm moves smoothly along three axes — side to side, to and fro, up and down.

In essence, the disks are its read-only memory, giving the automaton a repertory of three poems — two in French and one in English — and four drawings, including one of a Chinese temple.

“It’s amazing that it does it,” said Charles F. Penniman, a retired museum employee who gently tends to the automaton. “But it’s really amazing that it still does it after 200 years.”