Based on "The Art of Renaissance Science: Galileo and Perspective," a videotape by Joseph W. Dauben, CUNY Graduate Center and Lehman College.
http://www.mcm.acu.edu/academic/galileo/ars /arshtml/mathofmotion2.html
Examines Galileo's experiments with the inclined plane on a table, which were used to study projectile motion. Galileo correctly reasoned that projectile was subject to two independent motions, and these combine to provide a parabolic curve.