It was another attempt to compensate "mid-range temperature error" which it did not. With a serrated Balance wheel they are impossible to adjust but with the "normal" balance wheel, they are reported to run pretty well.

Finally, the use of nearly "0 coefficient of expansion" (el)Invar developed originally for glass to metal sealing Vacuum Radio Tube base Pins "won the day" for minimizing temperature error . . . with 0 temp coefficient, compensation was not an issue.

I can see how the temperature-stable Invar alloy simplified things, but I'm still not getting the serrated thing.

Unless it's got to do with wind-resistance(), I'm not sure how a bi-metallic unserrated wheel would differ from a serrated one.

Maybe his patent will answer the questions;

http://www.google.com/patents?...#v=onepage&q&f=false

Thanks Tom, that bit of detail clears up some things for me anyway....

Regards,

Jerry

Hi Sean;

Would you be interested in selling that watch, in a running condition, with that case?

If so, then I'd like to hear from you.

Bud

quote:

Here is another view showing the "Sparkle of the plates"

Thanks, Tom. I didn't realize the serrations were on the mating surfaces. How the %#&@ would you machine such a thing anyway?