The story of that demonstration of the concept of the bridge is really interesting. Before the days of electronics to be able to get such a concept across was a difficult proposition. The solution is very good and filled the bill well.
I have been on that bridge, by the way. It is a great view.
What I really like about the human model described here is that the humans could feel the tensile and compressive forces, rather than just imagine them. Seems like it would be a great exercise for engineering students.
This is definitely a great way to illustrate concepts of stress and strain! I'll have to keep this technique in mind when trying to explain mechanical problems. By the way, here is a picture (from Wikipedia):
Using words to let us paint our own mental picture is to me the essence of teaching. Teach us to read and imagine, then present a problem and describe a solution and let our minds create the picture and fill in the details. I read the article and had a pretty good concept of what was being described, when I saw the photo, it was obvious what had been described and the details clicked immediately into place. I think those of us who learned to read before there was television may be luckier than our children who had all the solutions presented visually before they developed the ability to imagine. I always enjoy your articles Professor Petroski.
Ken, You are absolutely correct. A picture is worth a lot of words, but it was my understanding that my column was not to be illustrated. Thanks to Mr. Palmer for inserting the classic photo into his comment. HP
This article may not be illustrated, but "Engineers of Dreams" is, and I remember the image shown below is in that book. I've kept it on my shelf waiting for my son to be old enough to understand and appreciate it as he heads towards an engineering career.
Sorry, Mr. P, I had no idea there was any such limitation, it seems I see photo's here quite regularly. Editor?
Bob from Maine, I'm quite proud of my ability to describe things accurately, but like most engineers regardless their artistic ability, I am always sketching stuff during discussions. One wouldn't commit schematics or drawings to a written description. Imaginations are way too variable to assure our minds are on the same page.
I'd seen this fantastic photo some time ago too, (Perhaps in Mr. P's book) and although it all sounded familiar, I still didn't put it together.
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