When a contract of sale is executory, as it always is where a particular article is ordered without being seen from one who undertakes it shall be of a given quality or description, and the thing sent as such does not conform to the order and is never completely accepted, the buyer is not bound to keep it, or pay for the article on any terms, though no fraud was intended by the vendor. But after the actual reception of the article, and the lapse of a reasonable time to examine it and to ascertain its quality and its conformity to the stipulations of the contract, the buyer will be deemed to have accepted it, unless he then promptly exercises his right to reject it. After full acceptance he is not at liberty, when sued for the price, to avoid the contract in toto. Granting that he may accept the article and retain his right to damages for noncompliance with the contract, it is well settled *289that his affidavit of defense must aver in clear and precise terms, when that is possible, the amount of the damages he has sustained. For example, this affidavit alleges that “the machine was not fitted with the wip-oilers for crank and cross-head which plaintiff agreed to furnish,” but is silent as to the deduction from the contract price which the defendant claims on this account. Again the affidavit alleges that the plaintiff agreed to keep the machine in repair for a year, that he did not keep his agreement, and that the defendant has been put to the expense of considerable repairs, but does not set forth the amount that it has thus been compelled to expend. We mention these as illustrations of the character of all the averments. It is not necessary to discuss them in detail. A deduction or set-off alleged in an affidavit of defense must be stated with exactness not only as to source and character, but also as to amount when the facts are within the defendant’s knowledge. “The importance of the observance of this rule is made the greater since the passage of legislation permitting the plaintiff to take judgment for such part of his claim as is not denied by affidavit of defense to be due: ” Anderson v. Williams, 10 Pa. Superior Ct. 329. See also Close v. Hancock, 3 Pa. Superior Ct. 207, Slag Works v. Krause, 5 Pa. Superior Ct. 622, Loeser v. Erie City Warehouse, 10 Pa. Superior Ct. 540, and Gausler v. Bridges, 13 Pa. Superior Ct. 646. This principle is applicable here inasmuch as the defendant does not allege that the machine is worthless or that it offered to return it. The court gave the defendant opportunity to file a supplemental affidavit, therefore it is not in position to ask for a relaxation of the rule.

Judgment affirmed.