Opinion of the Court.

faith, for the simple purpose of ascertaining whether it was what he claimed it to be. Did he do anything more than the inventor of the supposed machine might do in testing his invention? The public had the incidental use of the pavement, it is true; but was the invention in public use, within the meaning of the statute? We think not. The proprietors of the road alone used the invention, and used it at Nicholson's request, by way of experiment. The only way in which they could. use it was by allowing the public to pass over the pavement. Had the city of Boston, or other parties, used the invention, by laying down the pavement in other streets and places, with Nicholson's consent and allowance, then, indeed, the invention itself would have been in public use, within the meaning of the law; but this was not the case. Nicholson did not sell it, nor allow others to use it or sell it. He did not let it go beyond his control. He did nothing that indicated any intent to do so. He kept it under his own eyes, and never for a moment abandoned the intent to obtain a patent for it. In this connection it is proper to make another remark. It is not a public knowledge of his invention that precludes the inventor from obtaining a patent for it, but a public use or sale of it. In England, formerly, as well as under our Patent Act of 1793, if an inventor did not keep his invention secret; if a knowledge of it became public before his application for a patent, he could not obtain one. To be patentable, an invention must not have been known or used before the application; but this has not been the law of this country since the passage of the act of 1836, and it has been very much qualified in England. Lewis v. Marling, 10 B. & C. 22. Therefore, if it were true that during the whole period in which the pavement was used, the public knew how it was constructed, it would make no difference in the result. It is sometimes said that an inventor acquires an undue advantage over the public by delaying to take out a patent, inasmuch as he thereby preserves the monopoly to himself for a longer period than is allowed by the policy of the law; but this cannot be said with justice when the delay is occasioned by a bona fide effort to bring his invention to perfection, or to ascertain whether it

Opinion of the Court.

will answer the purpose intended. His monopoly only continues for the allotted period, in any event; and it is the interest of the public, as well as himself, that the invention should be perfect and properly tested, before a patent is granted for it. Any attempt to use it for a profit, and not by way of experiment, for a longer period than two years before the application, would deprive the inventor of his right to a patent."

We think that the present case does not fall within the principles laid down in Elizabeth v. Pavement Co. The plaintiff did not file a caveat, and there is no evidence that he did not intend to abandon his right to a patent. It does not appear that any part of the structure was made at his own expense, or that he put it down in order to ascertain its durability or its liability to decay, or that what he says he noticed in the spring of 1879 led him to make any further examination in that respect, or to test further the fear which he says he had at that time, or that what he then saw led him to think that the structure was weak or undesirable. It cannot be fairly said from the proofs that the plaintiff was engaged in good faith, from the time the road was put into operation, in testing the working of the structure he afterwards patented. He made no experiments with a view to alterations; and we are of opinion, on the evidence, that sufficient time elapsed to test the durability of the structure, and still permit him to apply for his patent within the two years. He did nothing and said nothing which indicated that he was keeping the invention under his own control.

In Smith & Griggs Mfg. Co. v. Sprague, 123 U. S. 249, 256, 257, it was said, Mr. Justice Matthews speaking for the court: "A use by the inventor, for the purpose of testing the machine, in order by experiment to devise additional means for perfecting the success of its operation, is admissible; and where, as incident to such use, the product of its operation is disposed of by sale, such profit from its use does not change its character; but where the use is mainly for the purposes of trade and profit, and the experiment is merely incidental to that, the principle and not the incident must give character

VOL. CXLVI-15

may

Opinion of the Court.

to the use. The thing implied as excepted out of the prohibition of the statute is a use which may be properly characterized as substantially for purposes of experiment. Where the substantial use is not for that purpose, but is otherwise public, and for more than two years prior to the application, it comes within the prohibition. The language of § 4886 of the Revised Statutes is that 'any person who has invented or discovered any new and useful machine not in public use or on sale for more than two years prior to his application, obtain a patent therefor.' A single sale to another of such a machine as that shown to have been in use by the complainant more than two years prior to the date of his application would certainly have defeated his right to a patent; and yet, during that period in which its use by another would have defeated his right, he himself used it, for the same purpose for which it would have been used by a purchaser. Why should the similar use by himself not be counted as strongly against his rights as the use by another to whom he had sold it, unless his use was substantially with the motive and for the purpose, by further experiment, of completing the successful operation of his invention?"

In that case, Elizabeth v. Pavement Co., supra, was cited with approval, and it was said (p. 264): "In considering the evidence as to the alleged prior use for more than two years of an invention, which, if established, will have the effect of invalidating the patent, and where the defence is met only by the allegation that the use was not a public use in the sense of the statute, because it was for the purpose of perfecting an incomplete invention by tests and experiments, the proof on the part of the patentee, the period covered by the use having been clearly established, should be full, unequivocal and convincing." The court came to the conclusion that the patentee unduly neglected and delayed to apply for his patent, and deprived himself of the right thereto by the public use of the machine in question; and that the proof fell far short of establishing that the main purpose in view, in the use of the machine by the patentee, prior to his application, was to perfect its mechanism and improve its operation.

Syllabus.

So, too, in Hall v. Macneale, 107 U. S. 90, 96, 97, it was contended that the use there involved was a use for experiment; but the court answered that the invention was complete, and was capable of producing the results sought to be accomplished; that the construction, arrangement, purpose, mode of operation and use of the mechanism involved were necessarily known to the workmen who put it into the safes, which were the articles in question; that, although the mechanism was hidden from view after the safes were completed, and it required a destruction of them to bring it into view, that was no concealment of it or use of it in secret; that it had no more concealment than was inseparable from any legitimate use of it; and that, as to the use being experimental, it was not shown that any attempt was made to expose the mechanism, and thus prove whether or not it was efficient.

In Egbert v. Lippmann, 104 U. S. 333, 336, the court remarked: "Whether the use of an invention is public or private, does not necessarily depend upon the number of persons to whom its use is known. If an inventor, 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 secrecy, and it is so used, such use is public, within the meaning of the statute, even though the use and knowledge of the use may be confined to one person."

Without examining any other of the defences raised, we are of opinion that the bill must be dismissed, for the reason stated by the Circuit Court.

Decree affirmed.

WASHINGTON AND GEORGETOWN RAILROAD COMPANY v. DISTRICT OF COLUMBIA.

APPEAL FROM THE SUPREME COURT OF THE DISTRICT OF COLUMBIA.

No. 27. Argued and submitted November 10, 11, 1892. Decided November 21, 1892.

With certain exceptions, within which this case does not fall, the statutes regulating appeals from the Supreme Court of the District of Columbia

Statement of the Case.

only apply to cases where there is a matter in dispute measurable by some sum or value in money.

The appellate jurisdiction of this court, when dependent upon the sum in dispute between the parties, is to be tested without regard to the collateral effect of the judgment in another suit between the same or other parties; and this rule applies to a bill in equity to restrain the collection of a specific tax levied under a general and continuing law.

In such a suit the matter in dispute, in its relation to jurisdiction, is the particular tax attacked; and unaccrued or unspecified taxes cannot be included, upon conjecture, to make up the requisite jurisdictional

amount.

THE Washington and Georgetown Railroad Company filed its bill in the Supreme Court of the District of Columbia, on October 23, 1884, against the District of Columbia and the Commissioners of the District, alleging that it was a corporation duly organized under the act of Congress in that behalf; that under the act of Congress of February 21, 1871, entitled "An act to provide a government for the District of Columbia," (16 Stat. 419,) the legislative assembly of the District passed an act, August 23, 1871, entitled "An act imposing a license on trades, business and professions practised or carried on in the District of Columbia," the twenty-sixth paragraph of the twenty-first section of which was in the words and figures following, to wit:

"The proprietors of hacks, cabs and omnibuses, and street cars and other vehicles for transporting passengers for hire, shall pay annually as follows: Hacks and carriages, ten dollars; one-horse cabs, six dollars; omnibuses, ten dollars; street cars, six dollars, or other vehicles capable of carrying ten passengers or more at one time, ten dollars."

And the fourth section, (omitting a proviso,) was as follows: "That every person liable for license tax, who, failing to pay the same within thirty days after the same has become due and payable, for such neglect shall, in addition to the license tax imposed, pay a fine or penalty of not less than five nor more than fifty dollars, and a like fine or penalty for every subsequent offence." (Laws Dist. Col. 1871, 1872, 1873, pp. 87, 88, 97.)

The bill further averred that, in pursuance and execution.