Pictures of the Allais Paraconical Pendulum

Here are some decent scans of the only pictures that seem to be available of the Allais Paraconical Pendulum apparatus. Of course, as per usual, you can store these pictures on your computer by right clicking them. If you print them each filling its own page, they look very decent.

The only thing you can't see clearly in these pictures is the all-important support ball, or "bille" as Allais calls it. This consisted of a commercial SKF ball bearing of 6.5 mm diameter. A new support ball was used for each twenty minute experiment. The ball rolled upon the support plate labeled S in the fourth and last figure, and was (presumably) held in a depression in the (non-labeled) cylindrico-conical mount shown as projecting downward from the bracket E. So the entire pendulum was supported upon this little ball. The idea was to eliminate sliding friction and to have no friction except rolling friction.


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