  Many instruments of the Historical Collection of the Physics Instruments of
the University of Palermo date back to the early nineteenth century, when
experimental Physics begun to be taught in university studies by using
instruments and apparatuses in the classroom to illustrate the laws of Physics.
Among the various instruments belonging to the Collection, there are also the
so-called 'paradoxes', instruments with surprising properties that do not seem
to follow the laws of Physics. In this article we analyze two 'mechanical
paradoxes' of the Collection and discuss their possible educational use.
