Pendulum Device; T. E. Truitt, 1978
This is an over engineered version of the common sand pendulum which is widely sold in various versions and sizes as an executive’s desktop toy ingeniously called the “Pit & Pendulum” (et. al.). These sell for around $25.00 to well over $100.00 for a fancy one.
The pendulum configuration is a simple Blackburn’s Pendulum; which is essentially a “Y” swing; the bob rotates in infinite planes and the top of the “Y” imparts an additional back-and-forth motion to the pendulum. A Blackburn's Pendulum is also commonly found in science centers where it is sometimes presented as a sand dribbling Lissajous curve demonstration.This patent also mentions Cundy and Rollett's excellent book, Mathematical Models (1951) as a reference. It’s currently out of print, but I recently heard a rumor that this timeless classic may be rereleased in a new edition. It can still be found for sale on Amazon and eBay.
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