Demonstration device for the parabolic flight curve according to ‘sGravesande

The demonstration device according to Willem Jacob 's Gravensande and Pieter van Musschenbroek was first mentioned in the 1742 edition of Physices elementa mathematica, experimentis confirmata. It demonstrates the gravitational pull on a horizontally flying body, which flies along a parabolic trajectory after leaving the jump.
The jump is made of wood, the tilt angle of its base plate can be adjusted by three brass screws. A line of brass rings is mounted behind the jump on a parabolic path.      
The trajectory is predicted by the positioning of the brass rings. This device can be used to demonstrate Galileo’s postulate on the superposition of the constant horizontal velocity and the accelerated free fall motion.
The reconstruction is based on measurements taken from the instrument kept at the Rijksmuseum Boerhaave Leiden.