Scientific American (New York, Nov. 23) -- Albert Michelson’s harmonic analyzer was a 19th century machine that used gears to perform Fourier analysis mechanically. Bill Hammack, a chemical and biomolecular engineering professor at Illinois, has made a superb set of YouTube videos that show the machine in action. Along with U. of I. colleagues Steve Kranz and Bruce Carpenter, he also has put together a beautiful book illustrating exactly how it worked.