In Cuno Engineering Corp. v. Automatic Devices Corp., 314 U.S. 84, 91, 62 S.Ct. 37, 86 L.Ed. 58 (1941) the court, in support of its decision holding a mechanical patent involving the aggregation of old elements invalid, concedes that the functions performed by the patented article are new and useful. After citing and discussing numerous authorities, the court states: 'Under the statute (35 U.S.C. 31, 35 U.S.C.A. 31, R.S. 4886), the device must not only be 'new and useful', it must also be an 'invention' or 'discovery'. Thompson v. Boisselier, 114 U.S. 1, 11 (5 S.Ct. 1042, 1047, 29 L.Ed. 76). Since Hotchkiss v. Greenwood, 11 How. 248, 267 (13 L.Ed. 683), decided in 1851, it has been recognized that if an improvement is to obtain the privileged position of a patent more ingenuity must be involved than the work of a mechanic skilled in the art. ' (314 U.S. at page 90, 62 S.Ct. at page 40.)