The Gravity-Powered Calculator is an exhibit of the Exploratorium in San Francisco. It is presented by its American creators as an amazing device that extracts the square roots of numbers, using only the force of gravity. But if you analyze his concept construction one can not help but recall the research of Galileo on falling bodies, the inclined plane and the projectile motion; exactly what the American creators did not put into prominence with their exhibit. Considering the equipment only for what it does, in my opinion, is very reductive compared to the historical roots of the Galilean mathematical physics contained therein. Moreover, if accurate deductions are contained in the famous study of S. Drake on the Galilean drawings and, in particular on Folio 167 v, the parabolic paths of the ball leaping from its launch pad after descending a slope really actualize Galileo's experiments. The exhibit therefore may be best known as a "Galilean calculator".