Opinion by

When this case was here before, (100 Pa. Superior Ct. 76), we said that the facts averred in the affidavit of defense, if established to the satisfaction of the jury, made out a good defense; but we said nothing to intimate that it could be established by other than competent evidence.

The mistake of defendants’ New York correspondents, Clark, Childs & Co., in reporting to defendants the purchase of stock which the plaintiff had ordered defendants to buy, when in reality none had been bought by them for plaintiff’s account or otherwise, could not be proved by introducing in evidence a letter from said correspondents to defendants stating that *149 such an error had been made. This letter did not become competent evidence until there was first introduced testimony by the person or persons responsible for the alleged mistake, explaining how it had been made, who could be cross-examined by the plaintiff and the truth of such evidence tested in the usual way.

Only after there had been direct evidence of the alleged mistake by those responsible for or having first-hand knowledge of it, did the letter from Clark, Childs & Co., to defendants become, relevant as bearing on the question of notice to the plaintiff and the subsequent acts of the parties.

The first, second and fourth assignments of error are sustained. The judgment is reversed and a new trial awarded.