This settling would cause great inconvenience, as the gripping apparatus, which is carried by the rail through the medium of the car or dummy, must travel in a fixed position in the tube, thus making a frequent adjustment of the rails to the tube necessary. The space between the rails and sides of the tube was filled with sand, which could not be securely confined, as the joints in the tube were liable to open by settling, so as to require a frequent relaying of the paving or planking, and making the whole insecure, and expensive to maintain. In my invention the whole forms a single, rigid struc

ture."

The following are the drawings of the patent, Fig. 1 being a cross-section and Fig. 2 a perspective view:

Fig L

Fig. 2.

The specification says: "A is the main tie. bent so as to embrace the tube, and it has fastened to the ends suitably formed plates or chairs, B, to which the rails, G, are fastened, or, if stringers are used, they may be fastened directly to the ties. The ties may be of various shapes, but in this case I have used old T-rail, turned bottom up, with but one curve or bend, as this requires but one heat, and is thus cheaper. C are upright supports for the slot irons, having one end secured to the tie at points each side of the bend, sufliciently separated to form the necessary width for the tube. D are tie-rods, connecting said supports with the main ties or frames, through the chairs, rails, or stringers, as the case may be. The rods, D, may be fixed or may be screw bolts, having

two nuts at one end for the adjustment of the slot irons to or from each other during construction, or other equivalent means may be employed. E is the concrete, in which the ties or frames are imbedded at suitable distances to support the rails and slot irons, which form the top of the tube. This concrete forms a support for the ironwork, the bottom and sides of the tube, and a foundation for the paving, F, which fills the space between the rails and slot iron, thus forming an even and durable road way, which cannot settle below the level of the rails or slot irons, or cause a side pressure on the tube, as is the case where the roadway is supported on sand or other independent foundation. As nearly all the weight of the traffic is on the rails, the tendency of the rails to go down is resisted by a deep girder, of which the bent tie forms the top and this continuous mass of concrete forms the bottom. I am aware that concrete, as a material for foundations, underground sewers, and conduits, has long been well known, and that concrete, brickwork, or ironstone pipe might be used to form the tube between the iron ribs of the well-known construction without any particular invention, as these materials are as well known as wood; but it would be still subjected to all the danger of unequal settlement, and the short tie and stringer of wood require frequent renewal and adjustment to the level of the tube. It will be seen that a distinguishing feature of my invention is the connecting of the rails in the same structure as the slot irons and the tube, so that all the parts are maintained in their relative position, and whatever may occur to alter the place of one will have no effect, unless the change is sufficient to affect the whole structure." There are seven claims in the patent.

The answer sets up in defense a denial of the allegation of the bill that the alleged invention was not in public use or on sale for more than two years prior to the application for the patent; and it alleges that the invention had been in public and profitable use in the United States for more than two years before the date of the application. It also sets up want of novelty and noninfringement.

There was a replication to the answer, proofs were taken, and the case was brought to a hearing before the circuit court, held by Judge Wallace, and a decree was entered dismissing the bill. From that decree the plaintiff has appealed.

The opinion of the circuit court, found in 37 Fed. Rep. 673, passed upon a single question. The invention was put into use on the California street railroad, a cable road in the city of San Francisco, on April 9, 1878, the road having been built by the plaintiff, and put into regular operation at that time, and, as constructed, having embodied in it the invention described in the patent. The defendant contended that such use was a public use of the patented invention more than two years before the application, and

that, therefore, the patent was invalid. The plaintiff contended, and now contends, that such use was an experimental use, and that the application was filed within two years after the plaintiff became satisfied that his invention was a practical success.

Section 4886 of the Revised Statutes, which was in force when this patent was applied for and issued, enacts that a patent may be obtained when the invention has not been "in public use or on sale for more than two years prior to the application;" and section 4920 provides that it may be pleaded and proved as a defense in a suit at law or in equity on the patent that the invention "had been in public use or on sale in this country for more than two years before" the applica- | tion, or had been abandoned to the public.

From the time the cable road mentioned was put into operation, no change or modification was made in its plan or its details. In the summer of 1876, between May and the 1st of September, the plaintiff conceived the invention. Early in that year certain persons in California obtained a franchise for the construction of a wire cable road on California street, in San Francisco, and the plaintiff was led to believe that he would be called upon, as an engineer, to construct the road. He immediately commenced studying up the matter, to be prepared to recommend a plan of construction, whenever called upon. He testifies that he deemed it necessary in a cable road to get a smooth, even road way and track, and the tube or tunnel way for the cable and its carrying machinery strong enough to resist any tendency towards the closing of the slot, to provide for the grip shank, and to make a structure as a whole so permanent and durable as to stand the wear and jar of heavy street traffic, as well as of the car traffic which it was to carry; and that, for that purpose, he deemed it necessary to have a rib or yoke, with connections to the two rails and the two slot irons, so as to connect them permanently, such yoke to be imbedded in and supported by a surrounding mass of concrete to form a support and foundation for the ribs or yokes, the bottom and sides of the cable tube or tunnel, and a foundation for the paving of the roadway. He says that he explained this invention to several persons prior to September 2, 1876, and on that day discussed the subject and explained the invention in a general way at a meeting of the directors of the proposed road. Between that time and January 1, 1877, he made a model containing two of the ribs, with an outside casing and cover, and had the space between filled in with concrete, incasing the skeleton ribs and forming "the shut section" of the completed track and tube.

|

been in regular and successful use as a street railroad, carrying passengers for pay. The plaintiff was superintendent of the road from that time until the date of his application for the patent, and afterwards until 1883.

In explanation of his delay in applying for the patent, he testifies that before he began the construction of the road one of the projectors expressed a doubt in regard to the durability of such a structure, and a fear that the jar of street traffic, as well as that of the cars, would in time loosen the ribs, and separate them from the surrounding concrete, and the structure would thus fail; that doubts were expressed also by others: that, while the plaintiff believed that there was more than an even chance of its proving a durable and desirable structure, he still had some doubt in his own mind, which was somewhat increased by the doubts expressed to him by others, in whom he had confidence; that, as causes which would contribute to the destruction of the road, there were (1) the moving of cars over a rail connected to ironwork without the intervention of any wood; (2) the street traffic of trucks and teams, to which such a structure would necessarily be exposed; (3) the changes of temperature; and (4) the effect of time, and the danger of water following down the different members of the iron work, and the rust separating them from the concrete; and that there was no way of determining these matters but by a trial in a public street through a long period of time.

He was asked whether his own doubts as to the durability of the structure were present at any time after the road was in operation, and, if so, when, and by what they were caused. He answered "Yes," and said that during the spring of 1879 the road was extended from Fillmore street to Central avenue, by a wooden structure not nearly so durable or costly as the original road; that, in preparing for the extension, he had occasion to dig out and around, so as to expose some of the old structure; that he saw therein some indication of the loosening of the yokes in the concrete; and that he had some little fear at that time that some trouble might arise in that respect. He further testifies that the reason he did not apply for the patent within two years from the time when he first put the structure into use was that, if it proved weak or undesirable, he did not want any patent; and he did not feel certain enough of that fact until the year 1881.

But it does not appear that he expressed his doubts to the projectors of the road, either before its construction was commenced, or during its construction, or while he remained its superintendent after it was completed, or that he communicated to any one what he noticed during the spring of 1879, or that he entertained any fear arising therefrom.

The circuit court truly says, in its opinion:"

sideration for devising and consenting to the use of an invention which was designed to be a complete, permanent structure, which

was to cost a large sum of money, and which he knew would not meet the expectation of those who had employed him, unless it should prove to be in all respects a practically operative and reasonably durable one. If he had entertained any serious doubts of its adequacy for the purpose for which it was intended, it would seem that he would not have recommended it in view of the considerable sum it was to cost. At all events, he did not treat it as an experimental thing, but allowed it to be appropriated as a complete and perfect invention, fit to be used practically, and just as it was, until it should wear out, or until it should demonstrate its own unsuitableness. He turned it over to the owners without reserving any future control over it, and knowing that, except as a subordinate, he would not be permitted to make any changes in it | by way of experiment; and at the time he had no present expectation of making any material changes in it. He never made or suggested a change in it after it went into use, and never made an examination with a view of seeing whether it was defective, or could be improved in any particular."

It is contended by the plaintiff that the principles recognized by this court in Elizabeth v. Pavement Co., 97 U. S. 126, establish the patentability of the plaintiff's invention, notwithstanding its embodiment in the California street railroad. But the circuit court held that the proofs in the present case did not show a use of the invention substantially for experiment, but showed such a public use of it as must defeat the patent. The court further said that the facts were in marked contrast with those in Elizabeth v. Pavement Co., because there the use was solely for experiment.

In Elizabeth v. Pavement Co., the original patent was granted in August, 1854. The invention dated back as early as 1847 or 1848. Nicholson, the inventor of the pavement in question in that case, filed a caveat in the patent office in August, 1847, describing the invention. He constructed a pavement, by way of experiment, in June or July, 1848, in a street near Boston, which comprised all the peculiarities afterwards described in his patent, the experiment being successful. The pavement so put down in Boston in 1848 was publicly used for a space of six years, before the patent was applied for; and it was contended that that was a public use, within the meaning of the statute. This court, speaking by Mr. Justice Bradley, said that it was perfectly clear from the evidence that Nicholson did not intend to abandon his right to a patent, he having filed a caveat in August, 1817, and having constructed the pavement in Boston by way of experiment, for the purpose of testing its qualities; that he was a stockholder in, and treasurer of, the corporation which owned the road in Boston where the pavement was put down, and which corporation received toll for its use; and that the pavement was constructed by him at his own expense,

and was placed by him there in order to see the effect upon it of heavily loaded wagons, and of varied and constant use, and also to ascertain its durability, and liability to decay. It was shown that he was there almost daily, examining it and its condition, and that he often walked over it, striking it with his cane. This court held that, if the invention was in public use or on sale prior to two years before the application for the patent, that would be conclusive evidence of abandonment, and the patent would be void; but that the use of an invention by the inventor, or by any other person under his direction, by way of experiment, and in order to bring the invention to perfection, had never been regarded as a public use of it; and it added: "The nature of a street pavement is such that it cannot be experimented upon satisfactorily except on a highway, which is always public. When the subject of invention is a machine, it may be tested and tried in a building, either with or without closed doors. In either case, such use is not a public use, within the meaning of the statute, so long as the inventor is engaged, in good faith, in testing its operation. He may see cause to alter it, and improve it, or not. His experiments will reveal the fact whether any and what alterations may be necessary. If durability is one of the qualities to be attained, a long period, perhaps years, may be necessary to enable the inventor to discover whether his purpose is accomplished; and though, during all that period, he may not find that any changes are necessary, yet he may be justly said to be using his machine only by way of experiment; and no one would say that such a use, pursued with a bona fide intent of testing the qualities of the machine, would be a public use, within the meaning of the statute. So long as he does not voluntarily allow others to make it and use it, and so long as it is not on sale for general use, he keeps the invention under his own control, and does not lose his title to a patent. It would not be necessary, in such a case, that the machine should be put up and used only in the inventor's own shop or premises. He may have it put up and used in the premises of another, and the use may inure to the benefit of the owner of the establishment. Still, if used under the surveillance of the inventor, and for the purpose of enabling him to test the machine, and ascertain whether it will answer the purpose intended, and make such alterations and improvements as experience demonstrates to be necessary, it will still be a mere experimental use, and not a public use, within the meaning of the statute. Whilst the supposed machine is in such experimental use, the public may be incidentally deriving a benefit from it. If it be a grist mill, or a carding machine, customers from the surrounding country may enjoy the use of it by having their grain made into flour, or their wool into rolls, and still it will not be in public use, within the

*223

meaning of the law. But if the inventor allows his machine to be used by other persons generally, either with or without compensation, or if it is, with his consent, put on sale for such use, then it will be in public use and on public sale, within the meaning of the law. If, now, we apply the same principles to this case, the analogy will be seen at once. Nicholson wished to experiment on his pavement. He believed it to be a good thing, but he was not sure; and the only mode in which he could test it was to place a specimen of it in a public road way. He did this at his own expense, and with the consent of the owners of the road. Durability was one of the qualities to be attained. He wanted to know whether his pavement would stand, and whether it would resist decay. Its character for durability could not be ascertained without its being subjected to use for a considerable time. He subjected it to such use, in good*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 Barn. & 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 monop

oly 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 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 Manufacturing Co. v. Sprague, 123 U. S. 249, 256, 257, 8 Sup. Ct. Rep. 122, 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 principal, and not the incident, must gives character 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 section 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 applica