Philip M Despite a decade or more of internet access, I'm afraid that Google is still not my first reaction when I'm confronted by something new which I know is not in my books. 'smot' is such a case. I found it after I had posted to you initially on this subject and found http://jnaudin.free.fr... site but not the page detailing the gyroscope. I'm impressed by the elegance of his design and if I can find the time, I'd love to build one. I'd add a laser pointer and mirror arrangement to permit very long pointers and thus accurate and short response time measurements. Moving the centre of gravity up to the centre of suspension I think would also be useful. That search also revealed Donald Simanek's site. I'm sorry you feel the way you do concerning his essay. I've been to his site many times and always found his thoughts to be on the money. Have you looked at http://www.lhup.edu/~dsimanek/museum/unwork.htm#cheng? Scroll down to The Gravity Shield Engine. I was impressed. This whole area of unworkable devices is rewarding I think. Regarding his debunking of the 'smot' device. If it really works as you suggest, then you should be able to make a ring of them, five would probably be enough, such that as the ball falls from one (with its height gain) and drops into the next, then the next etc, you should be able to make the ball go around the ring forever -- or at least.until it wears out. The fact that I can think of that means that someone else should have thought of it long ago and industry should now be powered by them. The fact that this isn't so just bears out what Donald S says about these devices. Paul D Send instant messages to your online friends http://au.messenger.yahoo.com