Abstract
Joseph Stepling (1716-1778) founded the astronomical observatory in Klementinum college. The Astronomical tower was only used as a physical cabinet originally and models of planetary systems were kept inside.
We introduce the contact with the Royal Society in London and we present a part of Stepling's lecture notes on the trajectories of the bodies resulting from the impact of the central force. We introduce the interpretation of the given situation - the center of the gravity as the Earth and the moving bodies as the Sun, the Moon, the planets or comets which circulate on elliptic trajectories or another space bodies flying around on a parabolic or hyperbolic trajectory.