John McCarthy collects inventions that came too late to do much good, e.g., the non-pulsating candle wick. In this era of numerical machi- ning, we ought to be able to make interesting gears to solve mechanical problems of yesteryear. As a minor (and probably unoriginal) example, to minimize stripping, a smaller gear ought to have broader teeth and narrower notches than the larger gear it meshes with. This must be geometrically possible, at least sometimes, since you could delete alternate teeth from a(n even-toothed) larger gear and fill in the corresponding notches of the smaller one. However, if we view this as a deformation of gears with half as many teeth, we have lost something like half the tooth amplitude (proper term?), so there may be little advantage in desymmetrizing. We might get certain exotic ratios with differential planetaries where the ring and central gears differ by an odd number of teeth. This might be possible if those gears are in slightly different planes, slightly beveled, with slightly tilted planets spanning the gap. The planets or ring might have a hollow shaft coaxial with the central's, both driven (at different speeds) by one adjoining shaft bearing two gears. This would require "continuous" scalability of one gear and its mate on one of the coaxial shafts. I'd like to animate gears with improbably small numbers of teeth (3??, 4?). Can anyone save me the trouble of deriving the involute curves that avoid sliding friction? --rwg PS, apologies for my churlish Mahalingam ouburst. A few minutes of Google, or consulting with any Subcontinental would have taught me that it is a proud old name of long standing. E.g., Welcome to Shankar Mahalingam's homepage. Professor and Chair Department of Mechanical Engineering University of California, Riverside ... This gentleman has *absolutely no connection* with the villain in the up-and-coming Goldmember sequel. And all this is dinky by comparison with former African head-of-state Houphouet Boigny, which in his own language means "Pit of Excrement". "Oh Miss Rice, here's some xylo- caine in case you need to bite your cheeks during the introductions." SUBNARCOTIC OBSCURANTIC BUCCINATORS (You bet your mahalingam.)