The opinion of the Court was delivered by

*142I am of opinion, the evidence of a mistake * .... given by the plaintiff is in itself too vague and uncertain to countervail the receipts in full, the fairness and accuracy of which are testified by a witness of credibility and intelligence, and which ought the more especially to be final, as vouchers and documents were destroyed in consequence of the interchange of discharges: besides, the witness who was present ánd assisted, is ignorant of the fact, which is little more than suggested by the plaintiff’s witness. I also think, that the admission of proof on the subject of a mistake, when there was no notice of it on the pleadings, or in the plaintiff’s particular, was necessarily a surprise on the defendants, and ought not to have been suffered. I am, therefore, of opinion a new trial ought to be granted.