Jacob & Youngs (Jacob) (plaintiff) is a general contractor that built a country residence for Kent (defendant). The contract stated that Jacob was to be paid $77,000, and one specification in the contract was that all pipes used be manufactured in Reading, Pennsylvania. Jacob completed work in June 1914. In March 1915, Kent noticed that some of the pipe was manufactured in other places besides Reading. Kent demanded the pipe be replaced. Replacement of the pipe, however, would require substantial additional work and expense by Jacob. Additionally, the existing pipe was of the same quality as Reading pipe and was supplied based on an innocent mistake by Jacob caused by the inattention of its subcontractor. Jacob left the existing pipe untouched and asked for a certificate from Kent that the final payment of $3,483.46 was due. Kent refused to supply the certificate, and Jacob brought suit to recover damages. At trial, Jacob was not allowed to introduce evidence that the pipe installed was of the same quality as Reading pipe, and the jury entered a verdict for Kent. The appellate court reversed and granted a new trial.