Reynolds

Mr. Chief Justice Murray concurred.

1. Where the entire performance of a special contract has been prevented by one of the parties, or where its terms have been afterwards varied by the agreement of both parties, the action for the amount due for work and labor should be in the form of indebitatis assumpsit, and not upon the contract. In such ease the contract may be introduced in evidence by either party as an admission of the standard of value, or as proof of any other fact necessary to the recovery, and should be allowed . to go to the jury whenever it can aid them in attaining a sound conclusion.

2. There was enough evidence on the part of the plaintiff to be submitted to the jury, and the Court below was correct in refusing the non-suit.

3. The Court correctly ruled out the portion of BushnelPs testimony which was excepted to because he was not a mechanic, and not such an expert as to make evidence of his opinions about the masonry of the building.

4. The question to Carlisle might have been properly allowed, but its refusal has done no harm. It was asked upon the theory that the work *112 of plaintiff was unskillfully done. The jury have found against this theory…