ANOTHER FACET OF DA VINCI.

Byline: Daily News Staff Writer

Everyone knows Leonardo da Vinci's ``Mona Lisa.'' But his exquisitely detailed drawings of machines and human anatomy, locked away in European libraries for nearly 500 years and rarely seen by the public, have been as enigmatic as La Gioconda's smile.

The devices Leonardo depicted seem a bit odd - common crankshafts and spring motors and uncommon things like a flying machine, a submarine, a helicopter and a robot. But most of them are still used today: crankshafts are found in automobiles and spring motors in large clocks.

``He made thousands of drawings and probably built about 100 machines,'' said Paolo Galluzzi, the director of the Institute and Museum of the History of Science in Florence, Italy. None of Leonardo's original Renaissance models survive. Working from the drawings, Galluzzi and a staff of five at the museum's multimedia laboratory transformed them into more understandable computer images. These were then used to produce full-scale models. Now 56 of the models are on view in ``Mechanical Marvels: Invention in the Age of Leonardo,'' at the World Financial Center in New York City.