Opinion by

Mr. Justice Elkin,

This appeal raises the question of the sufficiency of the affidavit of defense filed in the case. The court below held the affidavit to be insufficient, and directed judgment to be entered for plaintiffs. It is argued that the affidavit is vague and indefinite in general, and not specific as to the items of set-off claimed. It is therefore insisted that being defective in these and other respects judgment was properly entered. While it may be conceded that the affidavit is inaptly *74drawn, it does set up a substantial claim of set-off. This court has said that an affidavit of defense is not to be framed with the technical accuracy of formal pleadings, nor subjected to the severe scrutiny which a fine critical skill may exercise, but it must exhibit all the elements of a substantial defense: Thompson v. Clark, 56 Pa. 33; Kaufman v. Cooper Iron Mining Company, 105 Pa. 537.

The affidavit as a whole comes fairly within this rule. We do not agree that under the facts of the case the defendant can be permitted to prove an entire failure in the performance of the contract on the ground that the work was not done according to the original plans and specifications. The acceptance of the building at the time of dedication was a ratification of the general changes made in the plans and specifications. The affidavit avers, however, that the acceptance of the building at that time was only conditional, and that the contractors agreed to complete the work after that time in a satisfactory manner. Certainly defendant was entitled to prove the truthfulness of this averment, and to show that the matters complained of had not been completed according to the terms of the conditional acceptance.

We cannot accept as sound the contention that the minutes of the corporation are conclusive of the matters therein contained. The rule is that such minutes are prima facie evidence of the facts therein stated, but parol testimony is admissible to explain or supplement them: Hamill v. Supreme Council of Royal Arcanum, 152 Pa. 537. In the present case the minutes relied on are ambiguous, their meaning doubtful, and, as translated, the question can be fairly raised whether an acceptance of the work was intended, or only an expression of opinion as to the progress being made. Under the facts, however, it was a question for the jury.

The defendant is entitled to prove at the trial the items of set-off claimed in the affidavit in so far as they relate to the averment that the work has not been completed according to the conditional acceptance at the- time of dedication.

Judgment reversed and a procedendo awarded.