¶1The plaintiff and defendant were partners. The plaintiff sold out his interest in the partnership by a contract in the following terms :
“This certifies that I, George A. Wiggin, have this day sold unto Edward S. Goodwin, my former partner in the ladder business, all my right and title in said business, and do hereby sell and relinquish all my claim upon all the property, both real and personal, heretofore owned by the firm of Wiggin & Goodwin. Also all accounts now due said firm. In consideration of the sum of eight hundred dollars ($800) paid to me by said Edward S. Good*391win, receipt whereof I do hereby acknowledge. It is understood that the personal accounts now existing between myself and the said Edward S. Goodwin are not included in this agreement.
Signed at South Berwick, Maine, this twenty-first day of Feb ruary, A. D., eighteen hundred and seventy-one.
Witness, H. A. Stone. George A. Wiggin.”
¶2This paper was duly stamped.
¶3The note in suit is the one then given for the sum of $800 and referred to in the above agreement.
¶4The sale by the plaintiff to the defendant was a dissolution of the partnership. The interest of a partner in the estate of a solvent firm is the share to which he would be entitled in the final adjustment of its affairs. His interest would be what would remain after deducting the amount he might owe the firm. The sale to the defendant amounted to a liquidation of the affairs of the partnership. The claim of the firm must be regarded as extinguished. Lesure v. Norris, 11 Cush., 328.
¶5There is no ambiguity, either latent or patent, in the transfer made by the plaintiff of his interest in the partnership. The personal accounts existing between him and said Goodwin exclude partnership accounts due from him to the firm. The phrase relates only to accounts between them as individuals. The evidence to show what the scrivener meant by personal accounts was properly excluded.
¶6The defendant offered to show that, subsequently to the delivery of the note and contract, it was agreed that the parties should meet and settle the amount each owed the partnership at the time of its dissolution; and that the balance against the plaintiff, if any should be found, should be allowed the defendant on this note, or be paid him; that they did meet on March 1,1871, and adjusted their copartnership accounts, and it was found that Goodwin owed the firm, at the time of its dissolution, $157 ; that Wiggin then owed it $776 ; that the balance was found to be $619, which Wiggin agreed to pay or allow on the note in suit. This testimony the court excluded.
¶7*392This evidence was of an agreement subsequent to the date of the assignment of the plaintiff’s interest in the firm. “The rule, that parol evidence is not to be received to vary a written instalment,” observes Shepley, J., in Marshall v. Baker, 19 Maine, 405, “excludes all previous and contemporaneous declarations, but it does not exclude independent and collateral agreements made after the contract is completed, whether on the same occasion or at a subsequent time. Such testimony is not used to vary the terms of a written contract, but to prove, that it has become inoperative by reason of a subsequent and independent one.” In Goss v. Lord Nugent, 5 Barn, and Ad., 65, Lord Denman states the law on this subject thus : “After the agreement has been reduced into writing, it is competent to the parties, at any time before breach of it, by a new contract not in writing, either altogether to waive, dissolve, or annul the former agreement, or in any measure to add to, or subtract from, or vary or qualify, the terms of it, and thus to make a new contract; which is to be proved partly by the written agreement, and partly by the subsequent verbal terms engrafted upon what will thus be left of the written agreement.” If the parties for reasons satisfactory to themselves modify their original agreement, they have a perfect right to do it, and when done it is not readily perceived why proof of such modification should mot be received.
¶8This evidence was admissible upon another ground. It was urged that there was a mistake in the assignment as originally drafted; that it failed to truly represent the actual contract, as made and understood. If there was a material mistake, and it was fully established, a court of equity would reform the contract in which the mistake existed. If a mistake may be rectified and the instrument reformed by a court of equity, much more may it be done by the parties. If done by them, it is equally valid as if done in pursuance of a decree in chancery. The evidence offered tends.to show that the defendant was entitled to an allowance as claimed; that the plaintiff admitted that fact; that a settlement was made of the affairs of the partnership accordingly; that a bal*393anee was found due the defendant; that the defendant promised to allow such balance upon the demand in suit. If the defendant can prove all this, he should be permitted to do it. The demands of justice require it. Default off. Gase to stand for trial.