By the Court, Mullett, Justice.
This is an appeal from a judgment of a County Court, rendered in December 1851, affirming a judgment of a Justice’s Court. It is clear that in such cases, this court exercises merely an appellate jurisdiction, and can review only the decisions of the County Courts, actually made upon matters brought and litigated, or claimed, before those courts (Dorr agt. Birge and Wells, 5 How. Pr, R, 323, and the *117cases there referred to). It would, therefore, seem to be an important preliminary step in the investigation of such cases, to ascertain what those matters were. By the statute providing for appeals from courts of justices of the peace, to County Courts, the appellant, to take an appeal, is required to make or cause to be made, an affidavit stating the substance of the testimony and proceedings before the court below, and the grounds upon which the appeal is founded (Code of 1851, § 353). Under the Code of 1848, which was in this respect the same as the present Code, the Oneida County Court (1 Code Rep. 103), and the Superior Court of the city of New York (2 Sand. S. C. R. 632, and note), decided that unless this requirement was complied with, by a particular specification of the grounds upon which the appeal was founded, the appeal was invalid and should be dismissed. This construction is in accordance with the letter of the statute, and if adhered to would add much to the regularity and certainty of proceedings on appeal in the County Courts, and save this court some labor and difficulty in reviewing the decisions of the County Courts in such cases. But a similar requirement, in affidavits for the removal of causes from justices’ courts to the common pleas, by certiorari, and expressed in nearly the same words (2 R. S. 255, § 171), was considered by the Supreme Court sufficiently complied with by an affidavit setting forth the substance of the testimony and proceedings before the justice, containing statements of the errors alleged to have been committed by him, without the addition of a more particular statement of the grounds upon which the allegations of error are founded (6 Wend. 544 ; 8 id. 509; 18 id. 550). This was the construction put upon the Revised Statute immediately after its adoption, and adhered to until the statute was superseded by the Code, and it is hardly to be supposed that the commissioners of the Code, or the legislature; desired or expected a different construction from the use of the same words; nor is the necessity for a particular and formal statement of the grounds upon which the justice’s judgment is sought to be reversed, so far as they are included in the proceeding before the justice, increased by changing the mode of review from a certiorari, to an appeal. In be tn cases the cause is reviewed, in respect to the proceedings pefore the justice as it *118appears on his return. By the former practice, the justice was required, in his return, truly and fully to answer all the facts set forth in the affidavit on which the certiorari was allowed. But if the affidavit did not show in the proceedings, or set forth any grounds of error, it was the duty of the common pleas to quash the certiorari, and the Supreme Court would grant a mandamus to compel it to do so (18 Wend. 550). If the ground alleged for error, was error "of fact, which the justice could not answer, it was brought before the court by an assignment of error of fact (12 Wend. 266). By the present'system the appellant’s affidavit and the respondent’s counter affidavit, if he sees proper to make one, are both served on the justice before he makes his return, and he is required to make a return to the appellate court, of the testimony, proceedings and judgment. The justice’s return is in some measure responsive to the affidavits of both parties, and either party may apply to have the return amended, if necessary. When the return is complete, it shows to the County Court, with sufficient certainty, the erroneous proceedings and decisions of the Justice’s Court, so far as the appeal is founded on them, without a more formal specification. But when the appeal is founded on some irregularity or error not contained in the proceedings before the justice, or in the language of the 366th section of the Code, when the appeal is founded on an error in fact, in the proceedings, not affecting the merits of the action, and not within the knowledge of the justice, the return can give the County Court no information on the subject. In such cases no errors or irregularities can be brought before the County Court, except by the appellant’s affidavit. He must, therefore, state in his affidavit, in addition to his statement of the testimony and proceedings before the justice, the grounds upon which his appeal is founded. This statement and the respondent’s counter affidavit are in such cases equivalent to an assignment of error of fact, and the answer thereto, and present questions which the court " may determine upon affidavit or upon the examination of witnesses (Code of 1851, § 366). This is clearly a simplification and improvement of the old system. In the case under consideration the errors complained of, if there were any, and upon which the appeal to the County Court was founded, were contained in *119the proceedings before the justice, and were committed by him. These are sufficiently apparent upon' the justice’s return to the County Court. The matters brought before us for review, are the judgment of the County Court, affirming the judgment of the Justice’s Court, and the premises on which it was found, and an examination must be confined to these subjects. The first material erroneous decision of the justice, which appears on the proceedings returned by him, was that by which he permitted the plaintiff to prove an important part of his assumed case, by his own declarations to third persons. The plaintiff had pretended to justify himself in abandoning the work he had undertaken to do for the defendant, at a specified price, and charge for what he had done, by showing a failure on the part of the defendant to .furnish funds as he had agreed to do, to enable the plaintiff to proceed with the work. Harper, a witness for the plaintiff, had testified that he worked for some time for the plaintiff on the house which he was building on Heacock street. That while he was at work he saw the defendant there talking with the plaintiff. On his cross-examination by the defendant the witness said, in substance, that he did not know the defendant then, but after he went away the plaintiff told him that he was the defendant, and that he could not get money from him to go on with the work. The plaintiff’s counsel on a reexamination of the same witness, asked him why the plaintiff did not go on with the work, and the justice under the objection of the defendant, permitted the witness to testify that the plaintiff told him that the reason why he did not go on with the work was, that the defendant would not pay him as .fast as he got along, under the pretence that that was a part of the conversation which the defendant had called out on the cross-examination. The whole subject of the cross-examination, so far as it is embraced by the question under consideration, was the knowledge which the witness had, that the man whom he saw talking with the plaintiff was the defendant. When he had answered that he had no knowledge of that fact, except what he got from the plaintiff, his cross-examination upon that point was exhausted. He had no right to go on and state what the plaintiff told him, nor does it appear by the justice’s return that the defendant inquired what *120the plaintiff told the witness, even on that subject; and if he had it did not authorize the plaintiff to call for his own declaration, on an entirely different subject, although they might have been made at the same time, or in the same conversation. This permission of the plaintiff to introduce his own statement as evidence, to prove the most important part of his case, was, to say the least of it, a palpable misapplication of the rule of evidence, which was referred to to justify it. Another material error committed by the justice on the trial, as appears by his return, was permitting the plaintiff to prove by parol a further or other agreement than the sealed one, under which he built the house, without showing that the said contract had been broken, rescinded, abandoned or had expired. This was objected to by the defendant, on the ground that parol evidence was inadmissible to vary the terms of another subsisting agreement on the same subject, under seal. But the justice permitted the plaintiff to give evidence tending to show a parol agreement on the subject of the sealed contract, while that, was in full force, materially varying the terms of the covenant against the defendant, as the ground upon which the plaintiff’s action was founded. This was a violation of a well settled rule of law to which it is believed there is no recognized exception (13 Wend. 71; 21 id. 628; 23 id. 82; 4 Hill, 584). The County Court should have reversed the judgment of the Justice’s Court on these grounds. In addition to the above errors, the justice’s judgment was clearly wrong upon the merits, and contrary to the justice of the case, as it appeared upon the trial. The justice certifies that his return contains the substance of the testimony and proceedings had before him, and yet it does not contain any legal evidence to support his judgment. The defendant proved that the plaintiffwas under a covenant to do the work which he did for the defendant The plaintiff attempted to show that this covenant was varied by a subsequent parol agreement. Besides the incompetency of parol ' evidence to have that effect, the plaintiff did not, even with the help of his own testimony, prove any parol attempt to vary the sealed contract. There was nothing in the conversation which he testified to, purporting to release him from any of the obligations of his covenant, or to impose any new obligation, in that *121respect upon the defendant; the most that the plaintiff’s testimony on this subject tended to show, was a parol promise of the defendant, without any consideration, to let the plaintiff have money as fast as he wanted it, to go on with the work; not as payment for the work, nor in lieu of the payments which the plaintiff had covenanted to receive when the work was done. This was wholly insufficient to produce the effect claimed for it by the plaintiff, and given to it by the justice. In such a case the County Court ought to have reversed the judgment of the Justice’s Court, and erred in not doing so (Carter vs. Dallimore and others, 2 Sand. S. C. Rep. 222; Adsit agt. Wilson & Chamberlain, ante p. 64). For the above errors the judgment of the County Court must be reversed. The judgment of the County Court and that of the Justice are reversed.