English: A depiction of a device that was designed by Charles Wheatstone. It is a table-top device that features the same properties as the Foucault pendulum. The helical spring acts as a spring that is free to vibrate in any plane that connects the attachment points of the spring. When the spring is vibrating and the platform is rotating, then the spring precesses, and this precession follows the same sine law as applies in the case of the Foucault pendulum. The article in which Wheatstone describes his device and his observations is available at wikisource: Note relating to Foucault's new mechanical proof of the Rotation of the Earth