It is insisted, for the plaintiffs in error, that the Court erred in adjudging the plea insufficient, which sets up a contemporaneous parol agreement to give credit upon the indebtedness, evidenced by the bill of exchange sued on, until the first of March, 1854. Cases are cited where it has been held, that parol evidence is admissible to prove an argreement, at the time of making a note, that it might be discharged in a particular way, other than by the payment of the money, expressed in the note. (1 Ala. 41, 357, and other cases cited in brief.) But these cases proceed upon the ground that such an agreement does not contradict or vary the terms of the written contract. (Ib.) A case is cited also to show, that an agreement, not to sue for a specific time is binding. (2 Mich. R. 408.) This is undoubtedly true, if the agreement be upon a sufficient consideration. (Ib. and cases cited.) But this is to be understood of subsequent, not of an antecedent or contemporaneous agreement. (1 Greenl. Ev. Sec. 303, 304.) And whether such an agreement will preclude the right to sue, during the enlarged time of performance given by it, or will only give a right to recover damages for its breach, is a question upon which the authorities are conflicting. The case cited maintains the former opinion. But the current authority is admitted to be the other way. The general rule, subject to a few exceptions not applicable to the present case, undoubtedly is, that parol evidence can not be received to contradict or vary a written agreement. (2 Phil. Ev. 357, 358, 6th Am. from 9th London edit.) And this rule operates to the exclusion of parol evidence of any prior or contemporaneous agreement, to vary the terms or legal effect of the written contract. The cases which illustrate and enforce the rule are collected in the notes to Phillip’s Evidence, Id. part 2, p. 593, note 295, where it is said, “ We find it either conceded or asserted in almost every “ case which speaks on this subject, that all oral negotiations, “ or stipulations between the parties, which preceded or accom- “ panied the execution of the instrument, are to be regarded as “ merged in it; and that the latter is to be treated as the ex*605-"clusive medium of ascertaining the agreement to which the “ contractors bound themselves. Parol evidence is admissible “ to explain and apply the writing, but not to add to, or vary “ its terms. This general doctrine has been recognized almost “ universally.”
Counsel for the plaintiffs in error construe the plea as setting up a parol agreement, at or before the making of the bill of exchange, not to sue, in any event, before the stipulated .time of payment; the time specified in the bill. If so, it was an agreement which varied the legal effect of the written contract, as to the time of payment; and is within the operation of the rule which excludes evidence of the parol agreement, in such cases. In an authority, cited and relied on by counsel, it is admitted, that it would not be competent to prove a parol agreement to contradict the writing, as to the time of payment. (1 Ala. R. 368.) Neither is it competent to vary, by parol, the legal effect of the written contract in that particular. The present is a mercantile contract, and such contracts are to be construed according to the rules and principles of mercantile law. And by that law, immediately upon the dishonor of the bill by non-acceptance, the holder had a right to demand payment of the drawer and indorsers; and in default of payment, he was entitled to sue them immediately. (Story on Bills, Sec. 321; Chit. on B. 340.) Such was the legal effect of the contract, which it was proposed to vary, by setting up a parol contract that the defendants were, in no event, to be called' on for payment, until the maturity of the bill, according to its face. This was clearly inadmissible. Thus, it is laid down, that, “ where a written contract appears on its face to be complete, “ you can no more add to or contradict its legal effect, by parol “ stipulations preceding or accompanying its execution, than “ you can alter it, through the same means, in any other re“spect.” (Note to Phil. Ev. before cited, and cases there cited.) The law, controlling the operation of a written contract, becomes a part of it; and, though proof of usage may be received, in certain cases, to interpret the meaning of language, *606or to ascertain the nature and extent of the contract, in the absence .of express stipulations ; yet it is not admissible to contradict what is plain, or to show a particular intention at variance with the clear legal import of the written contract. (1 Greenl. Sec. 292; Chit. on Con. 98.) Thus where the written contract is silent as to the time when the goods are to be delivered, the- law being that, in such a case, they are to be delivered within a reasonable time, it has been held, that parol evidence of the conversations of the parties may be admitted to show the circumstances under which the contract was made, and what the parties thought was a reasonable time for performing it; but that, parol evidence will not be admitted to prove a specific time at which they were to be delivered, for that would be to contradict and vary the legal interpretation of the instrument. (3 Sumn. R. 530; Chit. on Con. 107, n.)
The parol stipulation, or agreement, respecting the time of payment, which preceded or accompanied the execution of the written contract in this case, was merged in the written contract. Evidence of such an agreement, as it is insisted the plea sets up, that is, that the plaintiff should not seek payment of the bill, from the drawer and indorsers, until its maturity, according to its terms, in any event; or though it should be dishonored for non-acceptance, was clearly inadmissible, as contradicting the legal effect of the written contract. And the plea, setting up such an agreement, was, consequently, bad.
But the plea does not aver that the defendants were, in no event, to be called on for payment, before the time specified, It is true, as averred, that the time appointed for payment was the 1st of March, 1854. It so appears by the face of the bill. And it is not improbable that the pleader intended to state the contract as thus appearing ■ and to deny the legal consequence, arising by operation of law, from the dishonor, by non-acceptance, of the bill; rather than assert a right as arising from any other or different contract from that evidence by the bill itself. If so, he was mistaken as to the legal effect of the contract ; and in either view, the plea was rightly adjudged insufficient.
*607The remaining objection to the judgment relates to the allowance of interest. But, as observed by counsel for the defendant in error, there is nothing appearing by the record, by which it may be certainly seen, that any sum was, in fact, allowed as interest. The word “ interest” is used in the verdict and judgment; but in such a manner and connexion as to leave it doubtful whether it was not used as mere matter of form, in drawing up the verdict, and making the entry of the judgment. The amount of the verdict is less than the sum for which payment is stipulated in the bill. It is impossible to say what interest, or that any in fact, was computed and included in the verdict. And it is the well settled rule, that to authorize a reversal, it must not be left doubtful, but must clearly appear that there is error in the judgment. Because it does not appear, we are of opinion that the judgment be affirmed.
Judgment affirmed.