The opinion of the court was delivered by
Garrison, J.
It was error to direct a verdict; the issues should have been submitted to the jury under proper instructions. The certificate of the engineer was not conclusive. Under the thirty-seventh clause of the contract payment is to be made upon the completion of the work, the certificate of the engineer and upon the said work being accepted by *236the mayor' and council. The certificate was not conclusive under this clause. Under the twenty-seventh clause “all material and workmanship shall be subject at all times to the inspection and supervision of engineer and supervisor, whose decision shall be final.” The certificate of the engineer was not conclusive under this clause, which called ■ for a joint certificate of engineer and supervisor. The circumstance that the supervisor had resigned and that his resignation had been accepted by the defendant and no new supervisor appointed does not operate to give conclusive effect to the sole certificate of the engineer. Where a power was given by will to be exercised by two executors or trustees, it required a statute to enable the survivor to execute the power. The parties to this contract had set up a tribunal the constitution of which could not be altered in invitum by either party. The supervisor could resign from his relation to the defendant alone, but he continued to be an essential factor of the joint tribunal. There was, therefore, no conclusive testimony to support a direction of a verdict. The, judgment is reversed and a venire de novo awarded.