Interplay between Airy and Coriolis precessions in a real Foucault pendulum.

This article focuses on a new model for analyzing the precession of a Foucault pendulum, incorporating both Airy precession—an intrinsic precession of an ideal spherical pendulum—and Coriolis precession caused by Earth's rotation, while accounting for anisotropy in the pendulum's support. The model characterizes support anisotropy through the difference between maximum and minimum oscillation periods along principal axes and uses an iterative numerical method to predict the pendulum's oscillatory trajectory and total precession rate. Experimental data from a 480.3 cm pendulum and historical parameters from Foucault's 67 m pendulum at the Pantheon of Paris validate the model, revealing that Airy precession can counteract Coriolis precession, potentially stopping precession under certain conditions. The study highlights the importance of controlling Airy precession—via support design or electromagnetic braking—to reliably observe Coriolis precession and suggests the model's utility in optimizing pendulum design for demonstrations and experiments.