Long time no see (like, 5.5 yrs)! Nonetheless, I'm back.
I've had this idea for a Volatility Wheel for a while. It's pretty simple/rudimentary, but seems certain to work.
Take a wheel with, say, 4 spokes (but the more the better). On the end of each spoke, attach a compartment filled with a volatile (i.e., low boiling point) liquid and sealed; (EDIT:)Dichloromethane might work great, but even water should work (just much more slowly). Put some kind of shaded covering over one half of the wheel (either left or right, not top or bottom), and put it in the sun. Voila! The sun-exposed side will evaporate into a gas, becoming lighter. The shaded side will condense and become heavier. It's turning!
I know this is not really a true PMM since it uses the sun as an energy source, but still I think it's interesting.
Last edited by frettsy on Sat Jul 12, 2014 8:01 am, edited 1 time in total.
Indeed! I had not seen the Minto wheel, although I had considered the similarity between my idea and the drinking bird. My idea is like an inverse of the Minto wheel, almost :)