delivered the opinion of the Court:
In the brief and argument of appellant it is said: “The substance of the controlling provisions of the lease and contract is, that the Illinois Central company agreed to furnish the Baltimore company with permanent freight station grounds and other terminal facilities, if, within the term of five years preceding November 1,1879, the Baltimore company so elected, in connection with an election to continue permanently the use of the Illinois Central tracks and right of way from the junction to and into Chicago. The failure on the part of the Illinois Central company to furnish the permanent freight station grounds, by the very terms of the agreement, gave to the Baltimore company the .-right to continue in the use and possession of the freight station grounds described in the lease, and which are here in controversy, until the possession of other ground's should, at least, be tendered. This absolute right of the Baltimore company to permanent freight station grounds, either the ones described in the lease or new ones, was contingent only upon the election of the Baltimore company, and notice thereof in writing.” The assumption that the contract and lease bound appellee absolutely to provide appellant with permanent freight station grounds, dependent only upon an election by the latter, and notice of such election, prior to November 1, 1879, to lease permanent freight station grounds, is not justified by the terms of those instruments. The grounds which, by the agreement, appellant might elect to take in perpetuity, were to be grounds upon the “Lake Front,” and the right was dependent upon two conditions : First, the exercise of the right of election, and notice thereof, within the time limited; and second, the legal ability of appellee to enclose and fill and give possession of such grounds on the “Lake Front.”
In this action under the Statute of Forcible Entry and Detainer, the judgment of- the trial court and judgment of affirm*27anee in the Appellate Court have conclusively settled all questions of fact in favor of appellee.
The facts of the case, as found by the courts below, are clearly indicated, not only by the judgments which they rendered, but by the statements of fact contained in the written propositions which the trial court held to be applicable in the decision of the case. We must assume, then, the facts of the case to be, that the term “Lake Front, ” used in the articles of agreement of July 27, 1874, had acquired at that time in Chicago, by popular usage, a known local meaning, signifying that portion of the lake shore extending from Bandolph street to Park Bow, and the submerged lands immediately adjacent to the lake shore; that the parties to the said articles of agreement were aware of that local meaning, and understood the term “Lake Front, ” as used in said articles of agreement, in that sense; that the freight station grounds described in the draft lease which accompanied the notice of election, dated October 23, 1879, are not a part of the land or ground specified in the articles of agreement; that the parties attempted to select ground other than that contemplated by the agreement of July 27, 1874, for permanent freight station grounds, and appellant gave notice of its election to take such new ground in perpetuity; that no completed agreement was made between the parties to make and accept a lease of the grounds specified in such notice, that no contract therefor was ever actually concluded, and that there was never any reciprocal and definitive assent of both parties to the same set of terms.
At the time the contract and lease were made, in 1874, the Illinois Central Bailroad Company was claiming the ownership of the submerged lands lying between Bandolph street and Park Bow, and extending about a mile into the lake, and was expecting to enclose and fillup such lands ready for occupancy. It was, however, at that time restrained by an injunction of the United States Circuit Court and an order of the War Department from so doing. The lease demised to appellant for *28freight station grounds the premises here in controversy, for a term to expire on March 1,1879. The lease also provided, “that if the second party elects to lease freight station grounds in perpetuity of the. first party, as specified in certain articles of agreement between said parties, bearing date the 27th day of July, 187.4, and shall give notice to the first party as therein-provided, then the first party agrees to extend this lease for a. further term on the same conditions, or furnish the second party a lease of other as suitable grounds for its freight business, upon terms to be agreed upon, until the first party delivers to-the second party the possession of the ground so leased in perpetuity, or is prevented from so doing, as specified in said articles of agreement.” The contract of even date provided: “And the said party of the second part shall have the above mentioned right to run its cars, engines and trains, under the obligations herein expressed, in perpetuity, if within said term of five years it shall so elect, and shall also elect to.lease the-freight station grounds hereinafter named of the first party in. perpetuity, and shall notify said party of the first part of such, election in writing. ” And said contract also provided: “ Should, the second party elect to, lease permanent freight station-grounds upon the Lake Front, the first party agrees to enclose and fill the same ready for occupancy, to an extent and in a. manner to be agreed upon between the parties. If the first-party shall be prevented by legal proceedings from enclosing and filling the said grounds before November T, 1879, then the arrangement herein between the parties hereto shall be continued for another term of five years, or for such portion thereof as may be necessary to enable the party of the first part to-obtain legal title to and to enclose and fill the ground aforesaid. Should the party of the first part be unable to secure the-. legal title before the expiration of three years from November 1, 1879, or should the second party be unable to obtain convenient and proper access to said permanent freight grounds, then, in either case, the party of the second part shall have *29the right to select other freight grounds not owned or claimed by the Illinois Central Bailroad Company. ”
At the' time of the negotiations between the parties in the fall of 1879, the status in respect to the submerged lands between Bandolph street and Park Bow was substantially the same that it had been in 1874. The Illinois Central company was still prohibited by the injunction and by the order of the Secretary of War from enclosing and filling said grounds. In that condition of affairs said company offered to appellant, for permanent freight station grounds, the lands lying east of' the premises in controversy, and all of which were north of the south line of Bandolph street produced, except a strip of unequal width, which wap necessary for an approach connecting the freight station grounds on the north with the main railroad tracks on the south.
One of the contentions of appellant is, that the term “Lake Front” meant simply land on or in the neighborhood of the lake shore; that it had no technical, prescribed meaning designating a portion of land on the Lake Front included between certain northern and southern boundaries; that the contract did not necessarily and exclusively mean land under water; that whatever the meaning usage had given to the term '“Lake Front, ” the acts of the parties themselves should be looked to in order to discover what was the meaning of the term “upon the Lake Front,” and that when appellee offered and appellant agreed to accept the lands which were in the fall. of 1879 designated for permanent freight station grounds, the parties construed for themselves the clause now in dispute. It is said, in argument: “The primary subject matter before the parties was the location of land under the old, not the new, contract.” It would seem that this is a begging of the ¡question at issue. At the time indicated certain specific grounds were agreed upon, but the designation of such grounds was not necessarily referable to an intended selection under the terms of the articles of agreement of 1874. The claim of ap*30pellee is, that in 1879 it was not in the power of the Blinois Central company to furnish the ground intended by the contract of 1874, and not in the power of the Baltimore company to occupy it, and that these facts were known to and recognized by the officers of both companies. In view of this claim, it is quite reasonable to suppose that the selection of specific grounds in 1879 was in furtherance of a mutual intention existing in the officers of both parties to abandon the grounds pointed out by the contract of 1874 for permanent freight station grounds, and enter into a new contract and lease for other and different freight station grounds. But a further discussion of this matter would be useless, for, as we have already seen, it has been conclusively determined by the judgments of the courts below that both parties to the articles of agreement of 1874 understood the expression “Lake Front/' as used in their contract, in the sense of signifying and meaning “that portion of the lake shore extending from Randolph street to Park Row, and the submerged lands immediately adjacent to the lake shore.”
The words and terms used in the contract of 1874 mean just what the parties mutually understood and intended them to mean when they executed such contract. This being so, and both lease and articles of agreement being instruments under seal, it is not competent, either at common law or under the law of this State, to modify or change them by proof of a subsequent parol understanding or agreement. (Chapman v. McGrew, 20 Ill. 101; Hume Bros. v. Taylor & Moss, 63 id. 43; Wittmer v. Ellison, 72 id. 301; Barnett v. Barnes, 73 id. 216; Loach v. Farnum, 90 id. 368.) This would exclude any theory that the parties, by their conduct in 1879, and thereafter, gave an authoritative interpretation to the clause now in dispute.
The first paragraph of the notice of October 23, 1879, if that had been all, would have been a sufficient and valid notice of election under the contract of 1874. The subsequent par*31agraphs and postscript and draft of lease referred to therein necessarily limit and qualify said first paragraph, and confine the election of appellant to the premises described in said draft of lease. It is claimed that construction should be given which would accord with the intent to perpetuate the contract, and that would uphold rather than destroy; that the subsequent paragraph of the notice and the draft of lease were but superfluous, and should be eliminated as surplusage. It is not perceived upon what principle, matter which is relevant and material can be rejected as mere surplusage. The relevancy and materiality of that which is sought to be left out of consideration is readily perceived when reference is had to the fact, that prior to the notice the parties had agreed upon permanent freight station grounds which were outside of the lands included in the articles of agreement of 1874. As is well suggested by counsel, the Baltimore company, after giving the notice, could not have been compelled to accept any grounds except those described in the draft of lease, and, as the obligation must be mutual, the Illinois Central company could not be compelled to furnish any grounds other than those described in the form of lease submitted.
It is suggested that this is to receive the attendant facts and circumstances, and proof of the proposed lease, for the purpose of invalidating the notice, and to exclude from consideration the fact that the notice was given and received as a notice under the contract, for the purpose of perpetuating it. The effect, upon that theory, would be to change by parol the terms of the contract under seal,—and this, as we have seen, can not, under the frequently declared law of this State, be done. It was no doubt intended by the notice to preserve the right of the Baltimore company to run its cars, engines and trains in perpetuity upon the tracks of the Illinois Central company. But this could not be done, under the contract of 1874, without at the same time electing to lease in perpetuity *32the freight station grounds named in said contract; and it has been authoritatively decided by the courts below, that the notice of election was for lands which are not those named in-said contract. It appears from the rulings of the trial court .upon the written propositions submitted to it, that that court' found the fact to be, that the parties agreed upon the selection of certain land for permanent freight grounds for appellant which were different from the grounds specified in the articles of agreement of 1874, but that the parties disagreed upon the terms of a lease therefor, and that no contract in respect to the same was ever actually concluded. Even if a lease of the newly selected freight grounds had been duly executed by the parties, such lease would not, without an agreement or stipulation to that effect, have extended the lease of 1874 for a further term, and until possession was delivered or tendered of the permanent freight station grounds so leased, nor have carried with it, under the circumstances stated, to the lessee, a legal right to demand an extension of the original term demised by the lease of 1874,—and this, because the obligation to extend the term of the original lease was dependent, as a condition precedent, upon the election by appellant to lease grounds specified in the articles of agreement for permanent freight grounds, and the giving of notice thereof is provided for in said articles.
It is claimed that the effect of the notice of election, without any new lease or contract, was to continue in force the existing covenants between the parties. The covenant in the lease of 1874, to extend that lease for a further term, or furnish appellant other as suitable grounds for its freight business until possession was delivered of freight grounds leased in perpetuity, is expressly made subject to the condition precedent that appellant first elects to lease freight station grounds in perpetuity, as specified in the articles of agreement, and gives notice thereof as provided therein. And the covenants for *33•extension in the articles of agreement are upon like condition that appellant “elects to lease permanent freight grounds upon the Lake Front,” and are for the express purpose of enabling appellee “to obtain a legal title to, and to enclose and fill, the ground aforesaid.” From the findings of fact as found in this record, it would seem that the contingencies in which the covenants for an extension of the old lease were to take •effect have never arisen.
At the trial the court held, as a proposition of law applicable in the decision of the case, in substance, that appellee is not estopped on equitable grounds, or by matter in pais, from insisting upon the fact that the premises referred to in the notice of October 23, 1879, were not the premises which ■appellant had the right to elect to lease in perpetuity under the provisions- of the lease and articles of agreement of July 27,1874, and refused to hold a proposition to the effect that if said notice of election was served prior to November 1, 1879, and no objection thereto was made, but that the president of appellee stated to the superintendent of appellant, who had served the notice, after the receipt thereof, on October 31, 1879, that he had received the said notice, and that it was the notice of election of the Baltimore, Ohio and Chicago Bail-road Company to run its trains and occupy the freight grounds in perpetuity, and that it was all right, then appellee is precluded from making any objections to said notice of election •or the form thereof, on the ground that said notice referred to grounds which are situate in part north of Bandolph street, or to grounds which are not upon the “Lake Front. ” It is plain that if, upon the theory of an equitable estoppel, appellee is precluded from claiming the notice in question was not such a notice of election as is required by the lease and contract of 1874, then such estoppel, if appellee persisted in its refusal to deliver possession of the new freight, station grounds selected, would work the result that the lease of 1874 would *34^est appellant with the right to hold perpetual possession of the premises thereby demised, and virtually convert said lease into a lease in perpetuity. It is the well settled law of this State that estoppels in pais, affecting permanent interests in land, can only be made available in courts of chancery, and can not be rendered efficacious as a means of defense in an action of ejectment, or forcible entry and detainer, or forcible detainer. St. Louis Stock Yards v. Wiggins Ferry Co. 102 Ill. 514; Same v. Same, 112 id. 384; Winslow v. Cooper, 104 id. 236; Blake v. Fash, 44 id. 302; Mills v. Graves, 38 id. 466 ; Wales v. Bogue, 31 id. 464.
Our conclusions, then, are, that the.notice of October 23, 1879, was not a valid and sufficient exercise of the right of election given by the lease and contract of 1874; that from and after November 1, 1879, appellant became and was a tenant from year to year of the premises here in controversy; ■ that by the notice of May 17, 1884, to quit and deliver up-possession on or before November 1, 1884, the tenancy was-terminated at the latter date, and that thereafter appellant; had no legal right to the possession of said premises.
The twelve written propositions of law that were submitted by appellee to the trial court, and held by that court, were in conformity with the views of the law herein expressed, and we find no error therein. The trial court was, perhaps, not strictly accurate in all of its rulings upon the propositions offered by appellant, but we find no substantial error in such rulings that would or could change the result reached.
The judgment of the Appellate Court is affirmed.
Judgment affirmed.