In re Yuan, 188 F.2d 377, 89 U.S.P.Q. (BNA) 324 (C.C.P.A. 1951) (full-text).
Appellate Court Proceedings Edit
The claim to an airfoil, drawn as an article of manufacture, does not define patentable subject matter where the sole novelty of the claim resides in the method of mathematical computation by which the profile of the airfoil is determined. Purely mental steps do not form a patentable process.