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Tensegrity Tower: Fourth email from Kenneth Snelson

To: Robert W Burkhardt <bobwb@juno.com>
Date: Mon, 3 May 1999 11:22:04 -0400
From: Kenneth Snelson
Subject: Monday morning

Hello again Bob,

Yes, the patent pictures look okay at your site.

Thanks for your thoughtful consideration. I wish I understood your math. My point about engineers trying to calculate these structures is that the figures anyone might come up with are only as good as the "tuning" of the tension lines. I made a sculpture years back at the Hochschule der Bundeswehr in Hamburg. There's a similar one at the San Diego Community College. Since the Bundeswehr is a military and technical school the powers-that-be decided the sculpture should undergo an analysis before I installed it. They had been given a small maquette to study. They completed their work in a couple of weeks -- offered me no copies of their figures (would have been meaningless in any case since I wouldn't have had any idea how to evaluate them) and I didn't delve into it since now I'd been given the green light to do my installation. They had found no reason to believe the sculpture would collapse.

In point of fact, with the same geometry, that is, the maquette as translated into a full scale sculpture, I could have tightened the piece like a stringed instrument so that indeed it would collapse from having too tight a tension network. Since the cables don't necessarily stress in identical ways the moment one cable is heavily tightened, the figures the Bundesweher engineers came up with could no longer describe what actually was going on since my tuning the piece was determining what stress were changing where. If the Bundeswehr engineers had any grasp of that complexity they would have given me a schedule of tightings they might prescribe as the optimum tuning to avoid trouble. That's the perplexity I'm talking about. That's the reason I question the success of engineers in analyzing such structures.

Kenneth S.

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