- posted 16 years ago
--Not sure if Google would be the place to search it, but many moons
ago there was an article in the Amateur Scientist column of Scientific
American about constructing a "ruling engine", a device for making optical
gratings. It used a principle called a "differential screw" to get
reeeeeally fine divisions using fairly simple components. You might want to
see if you can find a copy of the article.