delivered the opinion of the court.
This is a bill in the nature of a hill for specific performance of a written contract, filed August 5, 1908, by Joseph B. Strauss, appellant and hereinafter referred to as complainant, against Fred G. Borg, ap*467pellee and hereinafter referred to as defendant. The prayer of the bill was to the effect that upon the hearing a certain letters-patent of the United States, No. 828,873, for improvements in “bridges,” issued to defendant on August 21, 1906, be decreed to belong to complainant and that defendant be ordered to make an assignment of the same to complainant, that an accounting be had to ascertain the amount of royalties received by defendant from the sale of designs under said patent, and, if upon said accounting it be found that any monies be due from complainant to defendant, that defendant be decreed to pay the same to complainant in excess of any sum found due to defendant, complainant offering to pay defendant such sum. The defendant filed an answer to the bill and to an amendment to the bill, and after evidence was heard in open court the bill was dismissed for want of equity and complainant appealed to this court.
Both parties are civil engineers. On September 15, 1903, letters-patent of the United States, No. 738,954, was granted to complainant for improvements in “bridges,” upon application filed December 19, 1902. Sometime in the spring of the year 1903 complainant employed defendant to assist him in preparing designs and making calculations for proposed bridges. On October 15, 1903, the parties entered into a written agreement, for one year, wherein it was stipulated that complainant was ‘ ‘ the inventor and designer of an improved bascule bridge, an improved viaduct and other improvements, and the owner of letters-patent thereon,” and that defendant was to work for complainant as an assistant engineer in cliarge of the office and of such engineering work as complainant would carry on from time to time, but defendant was to receive no compensation for his services until complainant should obtain a satisfactory contract or contracts for the design and erection of one or more of his bridges or elevated structures, and when such contract *468had been obtained complainant agreed to pay defendant $140 per month, dating from May 1, 1903, to the time when such contract was obtained, and in addition thereto five per cent, of the net earnings on such contract and on any other contracts received for bascule bridges, and also on contracts for general engineering work done in the office. The agreement also contained the following provision: “It is hereby agreed and understood that all designs for said bascule bridge, viaducts, etc., and all improvements thereon, have been made by the party of the first part (complainant), and the second party (defendant) has no claim whatever on said designs and improvements, except as herein set forth, and all plans, designs, patents, etc., relating to said bascule bridge, viaduct and miscellaneous office work conceived or executed by either party, preceding this contract, or hereafter, belong exclusively to the party of the first part.”
Defendant remained in the service of complainant until June 15, 1905, during which time he did considerable work in preparing drawings for bridges and other structures for complainant, who was endeavoring to obtain contracts. No other written agreement was entered into between the parties during said period of service or afterwards. Defendant testified that after October 15, 1904, he had a conversation with complainant as to his future compensation and that the latter verbally agreed to pay him at the rate of $150 per month. Complainant denied this and testified that it was agreed that defendant was to continue to work for complainant on the old basis. About May 16, 1905, defendant asked for a payment of the back salary due him, and, according to defendant’s testimony, complainant at that time wrote and delivered to defendant a memorandum which, as defendant claims, showed that $1,662 was due defendant up to May 1, 1905. Shortly before defendant left complainant’s employ, a conversation was had in which defendant asked for a further *469increase in salary. Complainant testified as to this conversation: “I told him I conld not do so, and then lie said lie planned to go into business for bimself; * * * I said tliat would be satisfactory to me, and that I would be glad to help him along, * * * and I did that afterwards.” Complainant further testified: “He opened an office on the floor below, and I turned over to him there certain uncompleted jobs and made an arrangement to pay him on the hour basis, and gave him certain other pieces of work, * * * which he executed there. * * * This continued all through that summer and into the fall. ’ ’ In December, 1905, defendant again asked complainant for a settlement of the back salary due him and for work done subsequently to June 15, 1905. Complainant made a payment on account, and subsequently told defendant he did not owe him anything. In February, 1908, defendant brought suit against complainant in the Municipal Court of Chicago, and recovered a judgment of $1,151.90. On appeal this judgment was affirmed by this court. Borg v. Strauss, 153 Ill. App. 450. The Supreme Court granted a writ of certiorari, and subsequently, on December 21, 1910, affirmed the judgment (247 Ill. 462).
About six months after defendant left complainant’s office, complainant, on December 18, 1905, made application for letters-patent of the United States for improvements in bridges, which application was still pending at the time of the filing of this bill. On February 6, 1906, defendant filed an application for letters-patent for improvements in bridges, which was allowed on August 21, 1906, and a letters-patent was issued thereon to defendant. This is the patent which complainant seeks By this bill to have the court decree an assignment of to complainant as being rightfully his property. It is stated by counsel for complainant in their brief and argument filed in this court that,
“The particular type of bridge designed by the complainant and covered by his patent, is what is known *470as the trunnion type and derives its name from the fact that it moves upon a fixed axis or shaft called a trunnion, and moves upon this trunnion in very much the same manner as a wheel of a vehicle moves on its axle. The structure rests upon a pier or foundation on the bank and the bridge consists of a span called a leaf, which projects out across the channel, and this leaf is movable and can be raised for the passage of vessels, and in this movement swings upon the trunnion referred to. * * * The patent issued to the defendant * * * contains three principal features, viz:—
(a) An overhead counterweight,
(b) Supports entirely outside of the trusses, i. e., the foundation on which the structure rests consists of two pedestals, one on either side of the structure, neither one of which projects underneath the structure, or any part of it; and
(c) The counterweight supported by what is termed a compound lever.”
When complainant discovered that a patent had been issued to defendant, complainant filed an interference in the Patent Office, at Washington, D. C., which was heard and decided adversely to him. On appeal before the Examiners-in-Chief that decision, awarding priority of invention to defendant, was affirmed on November 30, 1908. Prom this decision of affirmance, which was introduced in evidence during the hearing of this case, it appears that said Examiners-in-Chief found:
“Borg’s application, though filed later than Strauss’, went to patent containing the claims that constitute the issue, and Strauss adopted the claims in his application; therefore what the invention is must be ascertained from the patent, and Strauss’ right to claim it depends upon whether the invention disclosed in his application is substantially the same as that particularly pointed out in the three claims taken from the Borg patent.
We do not find a compound lever in the invention disclosed in Strauss’ application prior to September 26, 1906, the latter being the date of filing of an *471amendment containing Stranss ’ claims constituting the counts.”
It does not appear that any appeal was taken from this decision of said Examiners-in-Chief.
The original bill charged, substantially, that the improvements set forth in the letters-patent issued to defendant had been developed by the complainant in the regular course of his business, while defendant was so employed by him, and as an outgrowth of complainant’s efforts to make further improvements in bridges beyond those covered by his patent, No. 738,954, and that by reason of the provision in the contract of October 15, 1903, above quoted, the said improvements mentioned in defendant’s patent rightfully belonged to complainant; that complainant had himself intended to make application for letters-patent upon the improvements contained in defendant’s patent, and subsequently did file an application for a patent therefor on December 18, 1905; that the specifications in the application filed by comp]ainant “covered all the principal features in the improvements specified in said letters-patent issued to defendant, * * * and each and every one of the improvements * * * were conceived and invented” by complainant while defendant was engaged in the office of complainant. By amendment to the bill the complainant charged, substantially, that the letters-patent issued to defendant represented a plan and design of a bascule bridge relating to the bridge described in the letters-patent No. 738,954 issued to complainant on September 15, 1903, and that under the provision in said contract, above quoted, complainant is the rightful owner of defendant’s patent and entitled .to an assignment thereof, “whether said improvements mentioned therein were conceived and invented by complainant, or whether the same were conceived and invented by defendant.” The defendant denied all of the allegations of the bill and amended bill, material to the present controversy, and *472set forth the decision of said Examiners-in-Chief as a bar to the relief prayed by complainant.
Upon the hearing, complainant offered in evidence the two patents, the contract, the various general drawings, computations, etc., of proposed bridges which had been executed in complainant’s office and under his direction by defendant, and produced expert witnesses who testified that in their opinion the said patent issued to the defendant related to the bridge covered by complainant’s patent and in what respects. The defendant’s evidence tended to show that during the existence of the written agreement in question none of the principal features so specified in his patent had come to his knowledge; that he first conceived the counterweight, compound lever and the trunnions, as he had them in his patent, shortly after he left the employ of complainant; and that there were material differences between the two patents, and between defendant’s patent and certain drawings for bridges either seen or made by defendant while in complainant’s employ.
The trial court found in the decree that the bill was in the nature of a bill for specific performance; that defendant commenced suit against complainant under said contract of October 15, 1903, which is the basis of the bill herein, and obtained judgment, which judgment was affirmed by the Appellate Court; that the use of the word “hereafter” (found in the clause in said contract on which this bill is based) is to be construed as having reference only, so far as its validity is concerned, to the time that the contract was in existence between the parties; that by the terms of said contract it was to last one year from the date thereof; that from a consideration of all the drawings and plans presented at the trial, and in the light of the expert patent attorney’s evidence, it was not established by a preponderance of the evidence that the patent, which was issued to defendant, was conceived by him while *473he was working for complainant; that complainant has not made ont such a case as would justify a decree holding that said patent is the property of complainant, and that, therefore, it is decreed that complainant’s bill be dismissed for want of equity.
One of the contentions of counsel for complainant is that the decision in the interference proceeding in the Patent Office does not in any way affect the right of complainant to sustain his bill. To this counsel for defendant replies that «“where the question decided in the Patent Office is one between contesting parties as to the priority of invention, the decision there made must be accepted as controlling upon that question of fact in any subsequent suit between the same parties, unless the contrary is established by testimony which in character and amount carries thorough conviction.” Morgan v. Daniels, 153 U. S. 120, 125; Hillard v. Remington Co., 108 C. C. A. 534; Greenwood v. Dover, 194 Fed. 91, 92. The chancellor in the decree in this case made no reference to the decision of said Examiners-in-Chief in the interference proceeding, but found that “it was not established by a preponderance of the evidence that the patent, which' was issued to the defendant, Borg, was conceived by him while he was working for said complainant” and that “complainant has not made out such a case as would justify a decree * * * holding that said patent is the property of the complainant.” In view of all of the evidence in this case we are of the opinion that said findings were fully warranted.
Counsel for complainant also urge as a ground of reversal that the chancellor erred in his construction of the word “hereafter,” used in the above quoted paragraph of said agreement of October 15, 1903, between the parties, and argue that such word should be so construed as to entitle the complainant to claim the ownership of all plans, designs, patents, etc., relating to the bascule bridge, conceived or executed by *474defendant at any time after the expiration of the one year period mentioned in the agreement, as well as during that period. We cannot agree with counsel.
In Dobbins v. Cragin & Co., 50 N. J. Eq. 640, Dobbins was engaged in the manufacture of soap and boot-polish. By written agreements he sold the use of his name and all interest in his plant to Cragin & Co., for a term of twenty years. Dobbins gave a receipt for part of the purchase price in which, above his signature thereto, were the words, “As a part of the foregoing agreement, the said Dobbins also hereby covenants and agrees with the said Cragin & Co. that they may use his name upon and as descriptive of any soap or blacking they may hereafter make, * * Dobbins, after the expiration of the twenty years, filed a bill to enjoin the further use of his name. The defendants contended that a perpetual right to the use of Dobbins’ name had been conveyed, but the court said (p. 648):
“The defendants rely upon the word ‘hereafter’ in it (the receipt) as indicating a grant in perpetuity to defendants to use complainant’s name upon any and all soaps and blackings the defendants may thereafter manufacture. Now, I think the word ‘hereafter’ used as an adverb does not necessarily refer to unlimited time. * * * It is not a synonym for ‘forever.’ It rather indicates the direction in time merely to which the context refers, and is limited by it. The duration of the word ‘hereafter’ is usually expressed by some other word, or is inferred from the context. In fact, the mind does not rest satisfied with the use of the word ‘hereafter’ in such case, but naturally inquires, and expects to hear in addition, how long the hereafter is to last.”
In Hildreth v. Thibodeau, 117 Fed. 146, a bill was filed in the U. S. Circuit Court for the district of Massachusetts, by Hildreth for specific performance of a written agreement wherein it was stated that Hildreth, a candy manufacturer, was desirous of having perfected and manufactured a certain machine or *475machines for nse in the manufacture of candy; that Thibodeau was a skilled mechanic and desirous of entering Hildreth’s employ for the purpose of perfecting such machinery; that Thibodeau, in consideration of such employment and the payment of certain therein specified daily wages, agreed to give Hildreth his best services and “the full benefit and enjoyment of any and all inventions or improvements which I have made or may hereafter make relating to machines or devices pertaining to said Hildreth’s business.” It appeared from the bill and the evidence in the case that complainant was notified by the Patent Office that another asked to have assigned to him under said contract; that while defendant was in complainant’s employ he worked upon a machine owned by complainant, upon which machine complainant applied for letters-patent of the United States, which application was subsequently allowed, and was about to issue, when complainant was notified by the patent office that another application for the same subject matter had been filed and an interference declared, which interference question had not been decided at the time of the filing of the bill, and that said other application for letters-patent had been filed by defendant. Defendant filed a cross-bill asking that the agreement be adjudged invalid and that it be delivered into court and can-celled, because it belonged to that class of unconscionable contracts which a court of equity will not enforce. The Circuit Court dismissed both bill and cross-bill because the bill had been prematurely brought, and for the reasons that the bill sought to have the court determine the question of priority of invention, that that question was now properly before the patent office for adjudication, that if it should be there determined that complainant was the prior inventor, this bill would fall because there would be nothing to assign under said contract, and that if it should be determined that defendant was the prior inventor it *476would then he time for complainant to ask for specific performance under the contract. The case was appealed to the Circuit Court of Appeals, first circuit (124 Fed. 892), where the decree was affirmed, the court saying (p. 893):
“Reasonably interpreted, the contract provided that Hildreth should take the benefit and enjoyment of all those inventions and improvements relating to machines used in Hildreth’s business which Thibodeau might make while employed by Hildreth. The employment might be ended at any time, either by Hildreth or by Thibodeau, and inventions thereafter made by Thibodeau would belong to him, and would not be covered by the contract. * *' * This contract is neither unconscionable nor against public policy.”
We have examined the cases cited by counsel for complainant which they say support their contention as to the construction to be given to. the word “hereafter” in the contract before us in this case, Joliet Co. v. Dice, 105 Ill. 649; Bates Co. v. Bates, 192 Ill. 138; Hulse v. Bonsack Co., 13 C. C. A. 180; Mississippi Glass Co. v. Franzen, 74 C. C. A. 135, and other cases, and are of the opinion that they are not applicable to the facts in this case.
Counsel for complainant also urge in their reply brief that complainant wrote out the agreement in question and submitted it to defendant for his signature, that he was unskilled in the preparation of legal documents and was a layman ignorant of the legal meaning of words, etc., and, therefore, these facts should be considered in determining the construction to be given to the word “hereafter.” This argument does not assist complainant, because, “if a contract contains ambiguous words, or words of doubtful meaning, such are to be construed most strongly against the party who executed the contract.’’ Massie v. Belford, 68 Ill. 290; McClenathan v. Davis, 243 Ill. 87.
Furthermore, in view of the action taken by com*477plainant, as above shown, in refusing to pay defendant money due him on said contract for salary, etc., for which defendant was obliged to bring suit and, after judgment obtained, to follow successive appeals to this and the Supreme Court, we do not think that complainant has brought himself within the rule that, before he can obtain a decree for specific performance of the contract, he must show that he has performed, or offered to perform, and has “always been ready, willing and eager to perform” his part of the contract. Wood v. Sheffer, 248 Ill. 617, 631.
The decree of the Circuit Court of Cook- county is affirmed.
Affirmed.