obvious distinction between a public use, or a use by the public, and an experimental use in public. In many cases it has been decided that a use in public, for test or experiment, is not such a public use as was contemplated by the act of congress, nor such a use as can be held evidence of dedication to the public. The Nicholson Pavement Case was notably one."1 "Public use in good faith for experimental purposes, and for a reasonable period, even before the beginning of the two years of limitation, cannot affect the rights of the inventor."2 "I agree his acts are to be construed liberally; that he is not to be estopped by licensing a few persons to use his invention to ascertain its utility, or by any such acts of peculiar indulgence and use as may fairly consist with the clear intention to hold the exclusive privilege." "It is clearly immaterial whether the experiment be made by himself or by others; the only question being, is he the original inventor of an art not before known or used?" 4 "It does not appear to me that the submitting of an invention to the test of examination by experts, in competition with other inventions, is the public use to which the statute refers. A use for the mere purpose of competitive examination, experiment, and test, is not a public use." 5

"I consider it too nice a point to say that the future patentee, when he permits a person to test his tool by a short use with a view to interest him in its being patented, is not testing his tool, but only the mind of the borrower. I do not know that an inventor is bound to satisfy his own mind alone by his experiments. The question to be determined is, not only whether the tool will work, but in what modes and with what advantages over old tools; how well it will work, and how cheaply; and I am of opinion that he may, in such a case as this, test not only its patentability, but the degree of it, if I may so say; that is, whether it is worth while to patent it. I must not be understood as speaking of a case in which the tool or thing patented has been sold more than two years before the application. " 6

"The evidence does not show any such public use or sale, with the consent of Dodge, for two years prior to his application, as would work a forfeiture of his patent. There is one case only of a sale clearly proved before February 14, 1855, and no evidence tending to show more than two or three sales before that time, and all of them accompanied with a notice of an intention to apply for a patent, and all of these during the time when he was experimenting upon and before he had perfected his invention, and attained sufficient perfection in the castings to satisfy him that his invention was practically successful. As in most, if not in all, of these instances the stoves were delivered on trial, to be returned if the invention did not work satisfactorily, they are to be regarded rather in the light of such practical tests as the law permits an inventor to make, than as such public sales as would tend to show abandonment, or mislead the public into a belief that the inventor had made a dedication to the public." On a rehearing of this case Judge LOWELL took a different view as to the effect of these sales, and held that the mere fact that they were conditional did "not, without further explanation, prove that they were experimental," and that "the evidence should be unequivocal that a test of the invention was one of the purposes of the seller." 8

1Strong, J., in Locomotive Engine Safety Truck Co. v. Pennsylvania R. Co. 1 Ban. & A. 484.

2 Birdsall v. McDonald, 1 Ban. & A. 167; Henry v. Francestown Soap-stone Stove Co. 2 Ban. & A. 223.

3 Story, J., in Mellus v. Silsbee, 4 Mason, 108; 1 Rob. 509. See, also, Jones v. Sewall, 6 Fisher, 364.

4 Washington, J., in Pennock v. Dialogue, 4 Wash. 538; 1 Rob. 472.

5 Shipman, J., in U. S. Rifle & Cartridge Co. v. Whitney Arms Co. 2 Ban. & A. 501. 6 Lowell, J., in Sinclair v. Backus, 4 Fed. Rep. 542; 5 Ban. & A. 84.

7 Shepley, J., in Henry v. Francestown Soap-stone Stove Co. 2 Ban. & A. 224.

8 Henry v. Francestown Soap-stone Stove Co. 2 Fed. Rep. 80; 5 Ban. & A. 110. See, also, Kells v. McKenzie, 9 Fed. Rep. 284.

"It is manifest that the only machine made in 1863, which is distinctly proved to have been sold, was delivered on trial and warranted, and should be regarded rather in the light of a use of the invention for such practical tests as the law permits an inventor to make, than as such a public sale or use as is contemplated by the statute. At that stage of the inventor's work his invention was largely in experiment and trial. It could only be tested by practical use in the field, and it was essential that it should be so tested by farmers on their farms. The inventor was then struggling, as inventors often do, to establish the success of his invention. It was necessary that thorough experimental tests should be made, and that he should have the assistance of others in making them; and it is manifest, we think, that the machines of 1863 were not yet so perfected as to be practical machines, capable of successful work." 1

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"If it was merely used occasionally by himself in trying experiments, or if he allowed only a temporary use thereof by a few persons, as an act of personal accommodation or neighborly kindness for a short and limited period, that would not take away his right to a patent.”2 “The law permits an inventor to construct a machine, * * * and place it in friendly hands for the purpose of testing it and ascertaining whether it will perform the functions claimed for it." "The use of an invention by special permission of the patentee is not a use of it by the public. * * A right abandoned to the public, doubtless, cannot be resumed; but a license restrained to individuals is not an abandonment." 4 "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 would be in public use and on public sale within the meaning of the law."5 And "to constitute the public use of an invention it is not necessary that more than one of the patented articles should be publicly used." 6

"He is not allowed to derive any benefit from the sale or the use of his machine without forfeiting his right, except within two years prior to the time he makes his application."7 But "it would be a harsh limitation of the statutory rights of an inventor which should give to a naked infringer the privilege of using an invention because the patentee had attempted, in good faith and in secrecy, to incidentally make his experiments of some pecuniary benefit, while he was patiently endeavoring, amid many failures, to remedy the defects of the machine, test its value, and ascertain whether it could be used advantageously, and whether it ever would be of any benefit either to himself or to the public." 8 And "whilst the supposed machine is in such experimental use the public may be incidentally deriving a benefit from it."9 "When an inventor puts his incomplete or experimental device upon the market and sells it, more than two years before he applies for his patent, he gives to the public the device in the condition or stage of development in which he sells it. * * ** His patent cannot be allowed to relate back and cover the forms of condensers which he gave to the public more than two years before he applied for his patent." 10

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AS TO DESIGN PATENTS. These rules also apply to design patents. "The law applicable to this class of patents does not materially differ from that in cases of mechanical patents. * * The same general principles of construction extend to both." 1 "An inventor is not permitted to exhibit his skill and taste in decorative art by the publication of elegant designs through a course of years, and then debar the public from any further use by obtaining letters patent for the same." 2

It will be observed that I have simply collated the authorities, and made but few comments and no criticisms. The language of some of the cases, particularly when they speak of the inventor's "consent and allowance,' should be understood with reference to the law then in force or governing the decision; but this does not affect their bearing on the general question of experiments. As to this question the following principles may be considered as fully established: (1) The law permits and encourages proper experiments to test and determine the practical utility of an invention; (2) these experiments must be made with reasonable diligence, considering all the circumstances of the case; (3) they may be made secretly or in public, by uses or sales, and by the inventor personally or through others; (4) they must not be for profit, but for the honest purpose of testing and perfecting the invention; and (5) where improvements are added within the two years, the patent cannot be allowed to relate back and cover forms previously given to the public. EPHRAIM BANNING.

Infringement of patent for the manufacture of combined ingots of iron and steel by means of moulds and a mechanism producing a variable cavity in the moulds.

2. SAME-INVENTION IN A FOREIGN COUNTRY.

The use or knowledge of the use of an invention in a foreign country by persons residing in this country will not defeat a patent which had been granted to a bona fide patentee who, at the time, was ignorant of the existence of the invention or its use abroad.

Francis Forbes, (with whom was A. Q. Keasbey,) for defendants. NIXON, J. These two cases will be considered together, for reasons which will hereafter appear. On March 5, 1881, the complainant, Illingworth, commenced a suit in this court against the defendants for infringement of letters patent No. 166,700, dated August 17,

1875, for "improvements in moulds for ingots." The defendants answered, setting up, among other things, that said letters patent were void (1) on account of prior knowledge and use of the alleged invention; (2) because every substantial and material part of the invention was described and claimed in letters patent No. 99,299, and granted to one Patrick Doyle, February 1, 1870, for "improvement in moulds for making combined ingots of steel and iron," and in English letters patent No. 3,801, issued to William Moore by the queen of Great Britain and Ireland, dated November 21, 1873, and sealed May 19, 1874; and (3) denying the right of the complainant to recover, because the defendants were the assignees and owners of letters patent No. 240,727, granted to one Alfred E. Jones, and were entitled to use the invention therein described and shown, notwithstanding the letters patent of complainant, on which the suit was brought.

It appears in the testimony that for several years previous to the filing of the bill, two of the defendants, Fitzsimmons and Jennings, were in the employ of the complainant's firm, and these became familiar with the use of moulds made under the Doyle patent, which is set up as anticipating the alleged invention of Illingworth. It also appears that the complainant used the Doyle patent for several years previous to 1875, in the manufacture of iron and steel ingots, the inventor Doyle, during the time being in business with the complainant; that the above patent was obtained by Illingworth in view of the fact Doyle was about going out of the firm, after which, it was supposed, that the continued use of his patent would not be allowed; and that he went out and remained away from the complainant from 1875 to 1880, when he returned and became the superintendent of his works.

On the seventh of May, 1881, Patrick Doyle began his suit against the defendants for the infringement of the letters patent, which had been set up in the former action as anticipation of the Illingworth patent. The answer of the defendants denies (1) that Doyle was the original and first inventor of the improvements therein claimed, and (2) alleges that every substantial and material part of the invention was known to several persons now residing in this country, and by whom it had been used in Sheffield, England, during their residence there.

Pending the taking of testimony in these suits, two applications were made to the court by the respective parties-one by the defendants in the Illingworth suit, asking that they might be allowed to amend their answer by inserting the allegation that the invention claimed by Illingworth was known to certain persons residing in this country, who used it in the city of Sheffield, England, before coming hither; and the other by the complainant in the Doyle suit, who moved to strike out the said allegation in the answer filed therein. The questions involve the interpretation of the clause, "not known or used by others

in this country," in section 4886 of the Revised Statutes, which first appeared in section 24 of the act of July 8, 1870, and which had never received judicial construction. Being willing to afford the parties an opportunity, without embarrassment, to correct any mistake which the court might fall into in deciding a matter of first impression, we allowed the allegation to stand in the answer in the Doyle suit and to be inserted in the Illingworth answer, and directed the parties to make their proofs of the facts and to present their views more fully at the final hearing. See Illingworth v. Spaulding, 9 FED. REP. 611. After a careful consideration of the provisions of the three sections of the patent act which bear upon the subject, (sections 4886, 4920, and 4923, Rev. St.,) we are of the opinion that the use, or a knowledge of the use, of an invention in a foreign country by persons residing in this country will not defeat a patent which has here been granted to a bona fide patentee who at the time was ignorant of the existence of the invention or its use abroad.

When the parties began to take the proofs they united in a stipulation that the evidence should be entitled in both causes, and that the two should be argued together. The defendants also admitted in writing, in each of the cases, that before the commencement of the suits, and since the granting of the letters patent, respectively, they had manufactured combined ingots of iron and steel in the following manner and for the following purposes:

(1) By means of a mould made in conformity to letters patent of the United States, No. 240,727, granted to them April 26, 1881, as assignees of Alfred E. Jones, a copy of which is hereto annexed, marked Complainants' Exhibit "Jones' Patent."

(2) By means of a mould made with two covers, in all respects like that shown in the above-named letters patent, except that there were two covers instead of one, and the slide was omitted. The covers are so made that a part of the cover first used projects into the mould. The process is as follows: The mould being clamped together, the first metal to be cast is poured into it, and, when sufficiently set, the cover is removed and a second one, perfectly flat, is inserted in its place. When this is done there remains a space between the newly-cast metal and the side or cover of the mould into which is cast the remaining part of the ingot. The mould is shown in the model, complainants' Exhibit E, where both covers are used and the slide is omitted-one cover having a projection into the mould and the other being flat.

(3) By means of a mould of three parts, each part being composed, as usual, in two-part moulds, of three sides rising from a closed base. The operation of the mould is as follows: The two parts of the mould are joined together in the usual manner by rings and wedges, and an ingot is cast therein in the usual way. Immediately that the metal is set, one side of the mould is removed and another, a little larger, is fixed by rings and wedges in the place of the side removed. Into the space thus made, adjacent to the glowing ingot of metal, the molten metal, to complete the ignot, is pared. When sufficiently cooled the combined ingot is removed, as is usual done in ingot moulds of two parts. This mould is represented by complainant's Exhibit F. The size and proportions of the parts, however, are not correct; only the arrangement and operation of the parts are intended to be illustrated.

(4) By means of a mould of two parts, in which one of the parts is like the