“[M]ere curiosities of invention, which do not have any intelligent purpose, are not useful in a patentable sense.” Roger Sherman Hoar, Patent Tactics and the Law 37 (3d ed. 1950).
“When applied to a machine, ‘useful’ means that the machine will accomplish its purpose practically when applied in industry. The word is given a practical and not a speculative meaning.” 60 Am. Jur. 2d Patents § 131 (1987).
