Public use or sale of the invention for more than two years before the application works an abandonment; Andrews v. Hovey, 123 U. S. 267. 8 Sup. Ct. 101, 31 L. Ed. 160 ; this is a conclusive presumption; Sisson v. Gilbert, 9 Blatch. 185, Fed. Cas. No. 12,912; and a single use is enough ; Egbert v. Lipp mann, 104 U. S. 333, 26 L. Ed. 755. But this rule does not apply to a strictly experimen tal use; Innis v. Boiler Works, 22 Fed. 780; no matter how long it had continued; Eliza beth v. Pay. Co., 97 U. S. 126, 24 L. Ed. 1000. A mere temporary use by a few persons as an act of kindness, for a limited period, or a use where the party using it is bound to se crecy, or is actually under the control of the inventor, or a use by the inventor in private is not within the rule; Wyeth v. Stone, 1 Sto. 273, Fed. Cas. No. 18,107. Such public use, with or without the consent of the subse quent patentee, renders the patent invalid; Andrews v. Hovey, 123 U. S. 267, 8 Sup. Ct. 101, 31 L. Ed. 160.
The sale which works an abandonment in this connection must be a sale in the usual course of business ; Henry v. Soap-Stone Co., 2 Fed. 78 ; and of the completed invention; id.; and merely placing the device on sale is not sufficient; Plimpton v. Winslow, 14 Fed.
919. A sale on trial, to test the invention, is not an abandonment, even though warrant ed; Graham v. McCormick, 11 Fed. 859.
Use by the inventor for the purpose of testing the machine, in order to devise means for perfecting its operation, is admissible where, as incident to such use, the product of its operation is disposed of by sale; such use does not change its character ; but where the use is mainly for the purposes of trade and profit and the experiment is merely inci dental to that, the principle, and not the in cident, must give character to the use; Smith & G. Mfg. Co. v. Sprague, 123 U. S. 249, 8 Sup. Ct. 122, 31 L. Ed. 141.
Where an invention was complete and capable of producing the result sought to be accomplished, and the construction and mode of operation and use of the mechanism were necessarily known to the workmen who put it into safes, which were the articles in ques tion, where it was hidden from view after the safes were completed and no attempt was made to expose the mechanism and thus prove whether or not it was efficient, it was held that it was not an experimental use ; Hall v. Macneale, 107 U. S. 90, 2 Sup. Ct. 73, 27 L. Ed. 367. If an inventor, after having made his device, gives or sells it to another to be used by the donee or vendee without limitation or restriction or injunction of se crecy, and it is so used, such use is public even though confined to one person ; Egbert v. Lippmann, 104 U. S. 333, 26 L. Ed. 755. Where the inventor of a connecting tie for rails used the device in constructing a cable road and reserved no future control over it, and had no expectation of making any ma terial changes in it, and never examined it to see whether it was defective or could be im proved, it was held that it was a public use so as to defeat the patent; Root v. R. Co., 146 U. S. 210, 13 Sup. Ct. 100, 36 L. Ed. 946.
But where the inventor of a wooden pave ment himself constructed an experimental pavement which was used for six years be fore the patent was applied for, and it ap peared that he built it at his own expense and went to see the effect of traffic upon it and its durability, and examined it almost daily, it was held that this was an experi mental use ; Elizabeth v. Pavement Co., 97 U. S. 126, 24 L. Ed. 1000. Where the inven tion is a machine, such as a grist mill, its experimental use does not cease to be so be cause its products have been sold. But if the inventor allows his machine to be used by other persons generally, with or without compensation, or if it is by his consent put on sale for such use, then it will be in public use and on public sale, within the act ; Root v. R. Co., 146 U. S. 223, 13 Sup. Ct. 100, 36 L. Ed. 946. Where thefe is no evidence of use or sale of the invention, which was a method of driven wells, by the applicant be fore his application, or by others with his consent, except putting down a single well, it was held that the use was merely experi mental ; Beedle v. Bennet, 122 U. S. 71, 7 Sup. Ct. 1090, 30 L. Ed. 1074.
The use of a telephone transmitter to test its efficienby is not a public use; Internation al Tel. Mfg. Co. v. Supply Co., 171 Fed. 651, 96 C. C. A. 395; nor is the use of a comput ing machine in the census bureau for a week ; Universal Adding Mach. Co. v. Comptograph Co., 146 Fed. 981, 77 C. C. A. 227; nor the use of a machine while being perfected, in a room from which the public and all others not engaged in its operation were excluded, improvements being made from time to time ; Penn Electrical & Mfg. Co. v. Conroy, 159 Fed. 943, 87 C. C. A. 149; nor' the building of a machine for a customer for experimental use by a purchaser, to be paid for if success ful, and which was abandoned; Huntington Dry-Pulverizer Co. v. Mill Co., 109 Fed. 269. But the commercial use of a machine for more than four years, though its operation was unsatisfactory to the inventor, leading to frequent experiments and the addition of an element of value, is a public use ; Risley v. Utica, 179 Fed. 876; and so where the dis coverer of a new form of calcium carbide made a considerable quantity to demonstrate its commercial use and sent a quantity abroad without enjoining secrecy; Union Carbide Co. v. Carbide Co., 181 Fed. 104, 104 C. C. A. 522; and so of the construction and sale of a turbine wheel and its use to drive machinery, although one object was to have a practical test made ; Swain v. Mach. Co., 102 Fed. 910 ; and of the exhibi tion of the subject of a design patent; Young v. Mfg. Co., 130 Fed. 150, 64 C. C. A. 502; and a single unrestricted sale of a machine ; Swain v. Mach. Co., 111 Fed. 408, 49 C. C. A. 419; and the manufacture and sale, with de livery, of a machine, on order ; National Cash Register Co. v. Cash Register Co., 178 Fed. 79, 101 C. C. A. 569; but not of a ma chine put out for trial "on sale or return," unless the trial period expired, or there was actual acceptance; W. B. Mershon & Co. v. Lumber Co., 189 Fed. 741.