delivered the opinion of the court.
*5672. Contracts, § 177 * —what effect given to clear intent of parties in construction of. In construing „a contract, greater regard should be had to the clear intent of the parties than to any particular words used to express such intention.
3. Contracts, § 183 * —when evidence of circumstances leading fo execution of contract admissible to aid in construction of. "Where a contract does not state on its face sufficient facts to enable the court to determine its true intent, and the terms of such contract are uncertain, evidence is competent of the circumstances leading to the execution of such contract, not as changing or modifying it, but to enable the court to place itself as nearly as possible in the position of the parties when such contract was made so as to understand the language used in the sense intended by the parties, and thereby arrive at its true intent, and to enforce the contract accordingly.
4. Contracts, § 183 * —when contract sufficiently uncertain to authorize admission of evidence of circumstances surrounding making of contract. In an action of assumpsit on a written contract by which defendants promised to pay a sum of money to plaintiffs, “subject to the final acceptance of the work done by the plaintiffs under their contract with O. T. Dunlap Company in building the sewer on St. Clair Avenue, etc.,” contract held sufficiently uncertain in its terms to render competent evidence of the facts and circumstances surrounding the making of the contract, in aid of its construction.
5. Contracts, § 294 * —when securing approval of work by city condition precedent to action by subcontractor against contractor. "Where contractors agreed to pay subcontractors for work done on a city sewer contract, “subject to final acceptance of the work,” and the contractors’ agreement with the city required that the work be done to the satisfaction of the Board of Local Improvements, and the contractors, upon failure of the subcontractors to secure approval of the work from the board, made the proper corrections and secured approval of the work, held that approval by the city of the work done by the subcontractor was a condition precedent to a recovery in an action of assumpsit on the agreement.
6. Contracts, § 171 * —when whole instrument considered in construing. In construing contracts the whole instrument must be considered, and such construction given as to give force and meaning to every part of it, if possible.
7. Set-off and recoupment, § 18*— when contractor may recoup expense of correcting defects in action by contractor. In an action to recover on a contract whereby defendants agreed to pay plain*568tiffs a sum of money on the acceptance by a city of certain work done by plaintiffs in pursuance of a subcontract with defendants, who had a contract with such city for the work, and Where it appeared that such city refused to accept the work as done by plaintiffs and only accepted it when defects in plaintiffs’ work had been corrected by defendants, the refusal of the trial court to permit defendants to set-off or recoup against plaintiffs’ claim the expense of correcting such defects, held erroneous, such payments being in such case money laid out and expended for plaintiffs’ benefit.
8. Contracts, § 393 * —when instruction as to admissibility of evidence to show nonacceptance of work and right of set-off proper. In an action by subcontractors against contractors on a compromise agreement for the payment of a sum in settlement for work performed on a city sewer contract conditioned upon acceptance of the work performed by the city, an instruction that it was competent to show that the city refused to accept the work done by plaintiffs until defendants had expended a certain sum in doing the work as required by the agreement, and that defendants might set off such sums necessarily expended, held proper.
9. Contracts, § 393 * —when instruction as to right of set-off proper. In an action by subcontractors against contractors on a compromise agreement for the payment of a certain sum in settlement of work performed on a city sewer contract conditioned upon acceptance of the work performed by the city, an instruction that if the contractor was compelled to incur expense in completing the work originally required of the plaintiffs before the work would be accepted by the city then the defendants were entitled to set off such expenses as had been necessarily incurred, held proper.
10. Contracts, § 393 * —when instruction as to admissibility of parol evidence to show nonacceptance of work, and as to right of set-off proper. In an action by subcontractors against contractors on an agreement to pay a certain sum in settlement for work performed on a city sewer contract and conditioned upon the acceptance of the work performed by the city officials, an instruction that it was competent for defendants to offer oral testimony to show that the work done by plaintiffs had never been accepted by the city in the condition it was in on the date that the agreement sued on was made, and that defendants might recoup necessary expense in completion of the work upon proof that plaintiffs, upon request to complete the work after date of the agreement, failed to do so.