OK, I may have most or all of the details wrong, because it was a long time ago (probably early 1980s)…
I remember an exhibit in the Boston Museum of Science with a spinning bicycle-type wheel inside a glass case. It was stated categorically that it was NOT a perpetual motion machine, but HAD been running for a long time, and challenged the visitors to determine how it worked (there was no explanation, you were supposed to write down your idea and put them in a box). I recall that there were some pipes inside angled towards the rim of the wheel, and may have been blowing on it.
Anyone have any idea what the hell I’m talking about?
I don’t think any of those are correct. The wheel was pretty solid, and had no obvious means of propulsion (i.e. no gears, chains, belts or motors). And I believe the description implied that no outside energy was being supplied.
Sounds very like the demos built by David Jones (best known as Deadalus in his columns for New Scientist and Nature). I’m not sure he’s ever gone public on how they actually work.
I remember that thing. I never found out the “real” reason either, but it sure looked like those little plastic boxes on the wheel rim would hold battery-powered electromagnets, well-aligned with the stationary metal plates they passed between.
I do remember it had some brass rods hanging from the edges of the hub, going down to plates that moved up and down over stationary plates on the base. Those could have been the poles of pulsed electromagnets, too.
My first thought was that the OP was talking about a Daedulus machine. I saw one at the Ontario Science Centre in Toronto in the early 1980s, and still have no idea how it worked.
One of my uncles had one of those fake perpetual motion machines you used to see a lot in the 80s. It consisted of a three-armed thingy that rolled along a plastic track that was lower in the middle than the ends. The trick was that there was a battery powered electromagnet hidden in the base under the track. When the battery ran out of juice, the spinny thing would keep going back and forth for a little while on inertia, but eventually would come to rest.
I was going to post that link. I saw one at the Science and Technical Museum in Vienna (third picture down, with the staircase in the background) and couldn’t figure out what kept it going. I’ve been meaning to ask about it here, but it sounds like I’d be out of luck.
There was text on the display case that may have explained it. Do we have any Viennese dopers who speak technical German?
On second look, and a complete reading of the article, it sounds like it may have been one of his (although it didn’t look like any of the wheels in the photos; less elaborate, IIRC).
I built a small one once. It was pretty neat. I don’t know if they’re availiable ready-made anywhere, but it’s not all that difficult to construct. If you do decide to try making one, I found that surgical rubber tubing is much better than rubber bands.
The time period you give falls exactly when I was away from Boston – I was there earlier and I came back afterwards, but was gone during the era of the “perpetual motion machine”, so I’ve never seen it.
Right now there is a Kinetic Sculpture by George Rhoads in the museum. It’s called Excogitation, and it’s been there for years:
http://www.georgerhoads.com/Monumental.html
The sculpture moves around billiard balls on the bottom section and larger balls (about the size of candlepin bowling balls0 on the top. But it’s not perpetual motion, and doesn’t claim to be. If you look, you can see the electric motors that keeps things going. The same guy did a kinetic sculpture for Logan Airport and, as you can see from his site, a lot of other places as well.
Descriptions of some “fake” perpetual motion devices can be found in David Ord-Hume’s book Perpetual Motion and in Martin Gardner’s In the Name of Science (AKKA Fads and Fallacies in the Name of Science).