Guglielmini Experimenting the Rotation of the Globe.

With the idea of creating a series of models that reproduces the most important scientific discoveries in the history, I propose this kit that portrays the experiment of the abbot and physicist Giovanni Battista Guglielmini.

He measured for the first time, the rotation speed of the earth in 1790.

To carry out his experiment he needed a very tall building and fortunately the abbot lived in Bologna which was famous throughout Europe for its medieval towers. Among these he chose the Asinelli tower which was built in 1100 and still stands in the center of Bologna known throughout Italy together with the Garisenda tower as Due Torri (the two towers). He climbed to the top of the tower and dropped metal spheres into it: he observed how the spheres were pushed by an apparent force that caused them to fall further east than where they intuitively should have fallen.

When the tower rotates together with the earth, the top of the tower is moving faster than the basement. The spheres actually keeps the same tangential speed when they fall down and this make the spheres falling far away from the vertical projection. The deviation from the vertical path together with the tower height allowed the abbot Guglielmini measuring the rotating speed of the globe.

Today it is possible to climb Asinelli tower, where people can see the holes made in the middle of each one of the floors to make the spheres passing through.

In the model, the intuitive falling path is described by a chain of transparent sticks and black spheres. The yellow sphere at the basement shows the position where the sphere actually falls. Professors of the ancient university of Bologna are observing the phenomenon with amazement.

I built this model to witness this challenging experiment taking place 60 years before Foucault pendulum performance of 1851. This also give me the opportunity to show a very famous middle age monument still sitting in Bologna city. Enjoy!