Inventive skill has been defined as "that intuitive faculty of the mind put forth in the search for new results, or new methods, creating what had not before existed, or bringing to light what lay hidden from vision ; it differs froth a "suggestion of that common experience which arose spontaneous ly and by a necessity of human reasoning in the minds of those who had become ac quainted with the circumstances with which they had to deal." Hollister v. Mfg. Co., 113 U. S. 72, 5 Sup. Ct. 717, 28 L. Ed. 901.
"Not every improvement is invention; but to entitle a thing to protection it must be the product of some exercise of the inventive faculties, and it must involve something more than what is obvious to persons skilled in the art to which it relates." Rosenwasser v. Berry, 22 Fed. 841.
"An invention, in the sense of the patent law, means the 'finding out-the contriving, the creating of something which did not ex ist, and was not known before, and which can be made useful and advantageous in the pursuits of life, or which can add to the en joyment of mankind." Conover v. Roach, 4 Fish. 12, Fed. Cas. No. 3,125.
"It was never the object of those [patent] laws to grant a monopoly for every trifling device, every shadow of a shade of an idea, which would naturally and spontaneously occur to any skilled mechanic or operator in the ordinary progress of manufactures." At lantic Works v. Brady, 107 U. S. 200, 2 Sup. Ct. 225, 27 L. Ed. 438.
"Originality is the test of invention. If that is successfully exercised, its product is protected; and it is immaterial whether it is displayed in a greater or less degree, or whether the new idea revealed itself to the inventor by a sudden flash) of thought or dawned on his mind after groping his way through many and dubious experiments." Blake v. Stafford, 6 Blatch. 195, Fed. Cas. No. 1,504. Whenever a change or device is new, and accomplishes beneficial results, courts look with favor upon it. The lax, in such cases, has no nice standard by which to gauge the degree of mental power or in ventive genius brought into play in originat ing the new device. A lucky casual thought, involving a comparatively trifling change, often produces decided and useful results, and, though the result of a small amount of inventive skill, the law extends to it the same protection as if it were the product of a lifetime of profound thought and most in genious experiment ; Middletown Tool Co. v.
Judd, 3 Fish. 141, Fed. Cas. No. 9,536. The patentee must be an inventor and he must have made a discovery. It is not enough that a thing shall be new and that it shall be useful, but it mtist amount to an inven tion or discovery ; Thompson v. Boisselier, 114 U. S. 11, 5 Sup. Ct. 1042, 29 L. Ed. 76.
The unsuccessful effort of others in the same art, to accomplish the same result, in dicates that the means by which the patentee has produced it are the result of inventive skill; Celluloid Mfg. Co. v. Zylonite Co., 28 Fed. 195; Dudgeon v. Watson, 29 Fed. 248. In The Barbed Wire Patent, 143 U. S. 275, 12 Sup. Ct. 443, 450, 36 L. Ed. 154, it ap peared that the sales of the earlier article had been but tentative and slight, and those of the patented article enormous. In sus taining the patent in suit, Brown, J., said : "Under such circumstances courts have not been reluctant to sustain a patent to the man who has taken the final step which has turned a failure into a success. In the law of patents it is the last step that wins. . . . It may be laid down as a general rule, though perhaps not an invariable one, that if a new combination and arrangement of known elements produces a new and bene ficial 'result, never attained before, it is evi dence of invention." The degree of invention is not prescribed by the statute ; Hillborn v. Mfg. Co., 69 Fed. 958, 16 C. C. A. 569; nor is it material; Washburn & M. Mfg. Co. v. Haish, 4 Fed. 900; each case must stand on its own facts, but if the patented structure is at the head of the evolution in its particular art and is a marked improvement on what preceded it, the court should surely be predisposed in its favor ; Bray v. Twine Co., 70 Fed. 1006. Courts give a liberal construction to the law, so as to protect every contrivance which can be called new, and which proves at all use ful. The inventor, therefore, has the bene fit of the doubt. But it is obvious that there is a limit beyond which mere changes can and ought not to receive this protection ; Kirby v. Beardsley, 3 Fish. 265, Fed. Cas. No. 7,837.