Wheels and Pendulums.

The Light Vehicle taught me some electronics and mechanics.  I also learned not to attempt too much technically. I also realized I didn't know anything about the aesthetics of movement. My education in the visual arts was entirely static. As a student, I had made some early motorized mobiles and some handmade films ala Norman McLaren. But my instructors never mentioned time based art. They sniffed at Calder and were not aware of Tinguely.  In 1965, kinetics was not within their purview of sculpture.
Wheel and Pendulum 2 (1970)

In 1968, I decided to investigate the kinetic relationship between a pendulum and a wheel driven by it. I screwed a rod into my studio wall as hanging point for a pendulum, attached a model airplane propellor to a small electric motor (slot car type) to its lower end.. When spun, the propellor's thrust would pull the pendulum parallel to the wall but out of plumb. The electricity to the motor was interrupted by a mercury switch mounted on the pendulum when the pendulum was tilted so. This negative feedback allowed the pendulum to swing back to vertical which would let electricity flow again pulling the pendulum out of plumb. Thus, the pendulum would swing at a rate determined by its natural periodicity, its friction overcome by the rhythmic thrust of the propellor. Transferring the pendulum's momentum to a wheel via a spring caused the wheel to spin and interfere with the pendulum's natural periodicity. Adding passive pendulums and more spring-linked wheels produced complicated behaviors.
The interplay between potential and kinetic energy was fascinating. I tried to balance pendulums' periods and wheels' momentums, varying the springiness of pendulum-to-wheel  connections, adjusting pivot points on the pendulums and the wheels and counterbalancing the pendulums to produce behaviors that were nonrepeating.  These systems of multiple pendulums and wheels could settle into a rhythm of movement for relatively long periods of time but then suddenly behave erratically for even longer periods. Sometimes they would change rhythms. A single arrangement could have several rhythmical behaviors and move from one to another, punctuated by random behaviors.
Years later, I was reminded of these patterns as I read about chaos theory with its strange attractors.

(van Doesberg's Bull)
When a combination of wheels and pendulums was adjusted to achieve a particularly pleasing behavior, it would be finalized by making the settings permanent, documenting the mounting holes, photographing it and storing it in its own crate. I made twenty of these sculptures before I came off the wall and built "Double Loop Feedback Tower."
Double loop Feedback Tower (1972)
Collection of Allan Stone

Besides being free-standing, the tower was different from the Wheel and Pendulum series, in that it consisted of two interrelated wheels and pendulums. They were connected by having the mercury switch that was affected by wheel and pendulum A control wheel and pendulum B and vice versa. This is the "double loop feedback" of the title.
When I finished this piece. I was ready to attempt once again an artwork that would use a stimulus outside itself.

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