Harmonograph
Similar to Pendulograph. A demonstration of Gravity and periodic motion. These devices were developed well over one hundred years ago and were a sensation. They are constructed of two pendulums swinging in straight lines at ninety degrees to each other whose combined motions create circular motions. The one shown here was built by Dale Pond and Jerry Williams and is now in the PSI Museum. It is very similar to the Pendulograph. It also serves to illustrate relative ratios as are found in music. When the two pendulums move at the same rate and amount the resulting patterns are circular. Vary the motions as the ratios of music intervals and the pattern varies accordingly. Thus rendering sound and gravity, in a manner of speaking, visible.
See Also
Gravity
Harmonic Vibrations and Vibration Figures
John Andrew
Pendulograph purchase this book
Pendulograph wiki entry
Proportion
Ratio
Visible Sound
Part 17 - Gravity
Table of Plate Harmonics and Intervals