The differential gear

The differential gear is a beautiful, elegant solution to the problem created by the fact that the wheels on a car need to rotate at different speeds. When you turn, for example, the outside wheel needs to rotate faster than the inside wheel. The differential gear allows that to happen.

I came to appreciate the differential gear in an undergraduate class I took on pragmatism. I don't remember much else from the class--C.S. Pierce's name is pronounced like 'purse,' William James is a nut, and that's about it. By far the most memorable thing about the class was the differential gear. I don't remember exactly how the conversation started, but it ended with the professor pulling out a laminated piece of paper he kept in his front shirt pocket that had a diagram of a differential gear on it. He put it in his pocket every morning and had done so for decades. It apparently really bothered him that he couldn't keep straight exactly how the gear worked--how the gears meshed, turned, etc. So he made a cheat sheet and kept it with him for all those times he happened to think about the differential gear and couldn't quite get a handle on how it worked.

Other than confirming that philosophers are in general a strange bunch, this episode resonates with me because I think it embodies what it means to be curious, motivated, self-directed, etc. He found something he was interested in, was bothered by the fact that he didn't understand it, figured out how it worked and made sure this knowledge wasn't just fleeting. He didn't learn it in a automotive mechanics class and there was no test he needed to memorize the workings of the gear in order to pass. It was born out of a desire to understand something and the motivation to do so.

As a bonus, it helped make him one hell of an interesting person. (He also had an obsession with the Levitron and had three different ones on his office desk, each of which he was happy to demonstrate if you visited.) I seem to recall him being a bit embarrassed by the fact that he had revealed his laminated differential gear diagram and, in response to the laughter, telling us we needed to cultivate more eccentricities. I think he was right.

I'm not exactly sure what the point of all of this is, except that I would love to teach a class where I could give some credit for deciding to carry a laminated diagram of a differential gear with you everywhere you go.