4 Blades Rotating Glass Windmill Solar Powered Crookes Radiometer Light Mill/Educational Teaching Study Tool/Office Home

Very well madeSpins effortlessly

Pro: It spins in direct sunlight.Con: There are slight defects in the black portion of the foils.Conclusion: Interesting device.

Over the years I've owned a number of radiometers. Some have simply stopped working (probably air leaked in) or they didn't spin well, or they got broken. The last one had to be in direct sunlight before it would spin. Fortunately it was knocked over by my cat and was broken forcing me to look for another one. This is the one I settled on. It was priced right and looked functional, not overly decorative. Well, when it arrived I opened the box, put it on an outdoor table (I was sitting outside on my deck) and it IMMEDIATELY started spinning... and this was while it was in deep shade with no direct heat source. Since then I've observed that as evening/night settles in it slowly stops, as I would expect, but then spins again early the next day. In fact just this morning I was having coffee on the deck as the sky lightened and, slowly at first, the radiometer began to turn. Without a doubt, this is the best radiometer I've ever own. Who ever did the glass blowing to make this radiometer deserves a gold star and a raise. It couldn't be better!

Over time it worked less and less. I eventually used a lightbulb to test it and surely it was working less and less. No cracks or damage, but now even in direct sunlight it will hardly move off at all. Great when it was new but not worth it if it only last a couple months.

VERY SENSITIVE! WORKS IN DIM LIGHT JUST FINE. I HAVE OTHER RADIOMETERS FROM A DIFFERENT COMPANY AND THIS ONE OUT SPINS THEM ALL!

This is a very cool solar power (thermal) gadget. Despite the silver side of the paddles were a bit dull, the unit rotates freely in sunlight even behind a slightly tinted office window. A cool throwback science demonstrator that never grows old.

We had these in school so I had to buy one.

Really soothing to watch this thing spin like a top in the morning sun. Would buy again and again, great gift!