Main Page | See live article | Alphabetical index Georg Purbach (1423 - 1461) was a German astronomer and mathematician. He is credited with the invention of several scientific instruments, including the regula, the geometrical square, and the "Jacob's Staff." Purbach was the author of a seminal work in astronomy, Theoricae novae planetarum. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.