*557 The cause was argued by Mr. Wheaton, for the plaintiff in error.

Mr. Chief Justice MARSHALL delivered the opinion of the Court, that the third plea was bad.

The agreement stated in that plea, although under seal, did not operate as an extinguishment of the simple contract debt. The agreement was but a collateral undertaking, to come to a settlement within a limited period, which had elapsed before the commencement of the suit, and to pay the balance found due upon such settlement. There was no averment in the plea that any such settlement had been had, under that agreement, and, consequently, the covenant to pay the balance did not appear to have attached upon the demand.