1. The plaintiffs in the original suit seek to avail themselves of a parol agreement, alleged to have been made between the parties to the mortgage at the time it was executed, by which each lot was to be bound only for a ratable proportion of the mortgage debt. The mortgage in this, as in ordinary cases, bound every part and parcel of the mortgaged premises for the entire debt, and if such a parol agreement, as is charged, can be proved and set up, it goes to vary, essentially, the operation of the mortgage deed.
*429This agreement is proved by Richardson, the mortgagor, as being concurrent with the execution of the mortgage, and part of the original agreement. It is as explicitly denied by the mortgagee in his answer. Two witnesses, however,. prove subsequent conversations with the mortgagee, in which the agreement was admitted, but the release executed by Cooper to Richardson, in October, 1797, and accepted by him, is pretty strong evidence that no such agreement was then understood to exist.
It is, however, unnecessary to enter into an examination of the weight due to the parol proof, for I am satisfied that the objection, upon the argument, to its admissibility, was well taken. There is no rule of evidence better settled, than that which declares that parol evidence is inadmissible to contradict, or substantially vary, the legal import of a written agreement. Such testimony is not only contrary to the statute of frauds, but to the maxims of the common law ; and the rules of evidence on this, or on most other points, arc the same in courts of law and of equity. (Lake v. Philips, 1 Ch. Rep. 59. Binstead v. Coleman, Bunb. 65. Parteriche v. Powlet, 2 Atk. 383. Irnham v. Child, 1 Bro. 92. Portmore v. Morris, 2 Bro. 219. Meres v. Ansell, 3 Wils. 275. Preston v. Merceau, 2 Black. Rep. 1249.) The general rule is certainly not to be questioned or disturbed. It ought not to be a subject of discussion. It is as well grounded in reason and policy as it is in authority. Nor docs this case come within any exception admitted here to the operation of the rule ; for there is no allegation of fraud, mistakcj or surprise, in making or executing the mortgage; and those, I believe, are the only cases in which parol evidence is admissible in this court against a contract in writing. (Marquis of Townsend v. Stangroom, 6 Ves. 328. Rich v. Jackson, ib. n.)
There is another rule which has some connexion with this branch of the law of evidence, and which will, in certain oases, and on certain terms, admit an agreement in writing. *430concerning lands to be discharged by parol. But the evidence in such cases is good only as a defence to a bill for a specific performance, and is totally inadmissible, at law or , ! , ' , . as a ground to compel a performance m specie. (Sugden, 109—114., 3d London edition, where the cases are collected.) And the rule has no sort of application to this case, which sets up a parol agreement as being part of the original agreement, and the professed object of which is to alter, by substantially restricting, the legal effect and operation of the mortgage.
2. The next and only remaining point in this case is, whether the release by the mortgagee, on the 24th of October, 1797, of four of-the lots included in the mortgage, does not, in equity, ratably reduce the power of the mortgage upon the remaining lots, inasmuch as it deprives the owners of those lots of their right of contribution as against the lots so released.
It is a doctrine well established, that when land is charged with a burden, the charge ought to be equal, and one part ought not to bear more than its due proportion ; and equity will preserve this equality by compelling the owner of each part to a just contribution. (Sir Wm. Harbert's Case, 3 Co. 14. Harris v. Ingleden, 3 P. Wms. 98, 99.) I need not go at large into this doctrine. It is perfectly well understood; and I had occasion recently to examine it in the case of Cheesebrough and others v. Van Schaick and others.* The court will likewise compel the creditor to aid this right of contribution, by assigning his bonds and securities to the debtor, or surety, or owner of the land, whom be charges with his whole demand, and they will not permit him, voluntarily, to defeat this right. He owes a duty to his debtors, not to impair their rights as against each other. But here the mortgagee has deprived the owners of lot No. 72. and 82. of this recourse, by previously discharging the other lots; and he ought not, then, in equity, to charge them with a greater burden than they would have been subject to upon *431the principle of contribution, if no such discharge had taken place. This is a clear and fundamental rule of justice, which must strike, at once, every discerning mind, and which Pothier has illustrated in his Treatise on Obligations, a work. which is founded in sound ethics as well as upon the basis of the civil law. (Traitè des Oblig. No. 275. 520.)
I shall, therefore, direct a reference to a master to ascertain the proportion of the principal sum mentioned in the mortgage, with the interest, that would, as between the owners of the several lots, be ratably chargeable upon each of the six lots contained in the mortgage; and that, in making such apportionment, due regard be had to the relative value of each lot at the date of the mortgage; and that he take such proof on this point, as the parties may furnish; and that he further ascertain and report the proportion of the debtthat lots 72., in Sempronius, and 82., in Camillus, would be jointly chargeable with upon such apportionment; and this latter sum, with interest, together with the costs of advertising under the mortgage, and after crediting what has been paid by the plaintiffs, is what they ought to be decreed to pay, or that the mortgage be foreclosed.
Decree accordingly.
Ante, p. 409.