¶1It is claimed that the court erred in finding that the sum of money paid by plaintiff to Merritt was for the redemption of the premises bought by Mills-of Saunders and Burley; and also in the method of computing interest. We think there is no eri'or in these findings of the court. The plaintiff in error eoul.d at any time have paid off this incumbrance, and having done so, would have been entitled to a credit on the note for the amount so paid; or if the purchase money had all been paid, he could have recovered the amount so paid, by suit, if the defendants in error had refused to pay the same; or he might have brought his action upon the covenants of warranty against the incumbrance; but he saw proper to permit the mortgage to be foreclosed and the premises to be sold, and then redeemed the- same by paying to the mortgagee his debt, costs and attorney’s fees. For the whole sum. of money so paid to the mortgagee, by the plaintiff in error, the court allowed him a credit upon *193the note. This he was entitled to and it was all he could in equity demand.
¶2But it is insisted that the court erred in its method of computation of interest in rendering its judgment against plaintiff in error. In respect to this question, the rule seems not only to be well established but to be just in principle, that interest on a judgment or debt due, is computed up to the time of the first payment, and the payment so made is first applied to discharge the interest, and afterwards, if there be a surplus, such surplus is applied to sink the principal, and so toties quoties- — taking care that the principal. thus reduced shall not at any time be suffered to accumulate by the accruing interest. Penrose v. Hart, 1 Dall., 379. Spires v. Hammet, 8 Watts & S., 18. Story v. Livingstone, 13 Peters, 371. Smith v. Shaw, 2 Wash., C. C., 167. Hammer v. Neville, Wright's Rep., 169.
¶3In respect to the sixth assignment of error it may be observed, that it seems impossible to discover in what way the evidence offered by plaintiff in error, in regard to the opinion or declaration of one of the defendants in error as to the legal liabilities of the parties to each other, could affect or change the final result of the case. The execution of the note and the price to be paid for the premises are not controverted, and the record clearly shows that Mills was credited with the full amount paid by him on the mortgage incumbrance. It is upon the facts, and the law fairly applied to these facts, that the matters in controversy between the parties must be adjusted, whatever may have been the opinion of any one of the parties as to their legal liabilities; and upon an examination of the entire record it appears clear that the evidence offered was immaterial, and therefore properly rejected.
¶4It is also insisted that the court erred in sustaining the demurrer to the third defense of the answer, which *194alleges that there were delinquent and unpaid taxes upon the premises, which were an incumbrance thereon, and it is asked that such taxes be set off against the sum found due upon the note. It is not alleged that these taxes have been paid by Mills, or that he had ever been called on to pay any portion of them. This defense is specifically one of set-off, and is not a count in the nature of an action upon a covenant of warranty against an incumbrance. It is a plain elementary principle of law, that until such incumbrance is discharged by the vendee of land, he is not damnified in such manner as to entitle him to plead such incumbrance, by way of set-off to an action for the recovery of any portion of the purchase money. Rawle on Covenants, 288-9. The demurrer was properly sustained.
¶5The judgment of the court below must be affirmed.
¶6Judgment affirmed.