Opinion by

The assignments in relation to the tender of releases of mechanics’ liens, as a condition precedent to plaintiffs’ recovery, cannot be sustained. The principle of law invoked is entirely sound, but it would be sticking in the bark to apply it to the facts of this case. The purpose of the clause in the contract was to protect the appellants from having to pay money a second time to mechanics or material men after having once paid *635it to plaintiffs. A lien filed, paid and receipted in full or satisfied of record is as complete a protection as a release. The only outstanding lien involved in this controversy was the subject of a bona fide dispute, and has been liquidated by judgment between the parties. Payment of it by appellants will be a good defalcation from the plaintiffs’ claim! The adjustment of this matter is entirely within the control of the court below upon execution.

The setting up by parol of a term of the contract in regard to the railroad siding, not included in the writing, raises one of the most difficult and uncertain questions in the whole range of the law. It may well be doubted whether justice would not be served by totally disallowing such evidence, and compelling parties to go into equity and have the contract reformed as an indispensable preliminary to a defence based, on such claim. But of the fact that material terms are at times omitted from even careful writings, the existence of the settled jurisdiction in equity is proof, and in the absence of a court of chancery our predecessors found it essential to justice to grant relief in such cases upon equitable principles under the forms of law, and the rule has now been too long and too firmly established for us to change it. We cannot say that the evidence in this case as to the siding was insufficient, and it was given to the jury with instructions that the burden was on the plaintiff to establish it as part of the contract “ by clear and distinct proof — such as to convince you that it was actually made as claimed by the plaintiffs.” This is the very language of defendants’ own eighth point, which was also affirmed. True it is the duty of the court, as argued by appellants, to pronounce as matter of law upon the sufficiency of the evidence, but leaving it to the jury was practically directing them that it was sufficient in law, if they believed it true in fact. That was a substantial answer to appellants’ point, and was not error. Nor can we say there was error in admitting the testimony of other parties as to the terms of the proposed contract stated to them by the defendants and their architect. It was corroborative of the direct testimony of the plaintiffs and was admitted in that view only. The letter of plaintiffs to defendants was competent on the same ground. When the case was here before, 139 Pa. 201, we were obliged to reverse on this point, because the *636plaintiffs had, no doubt inadvertently, omitted to prove that the letter was mailed or sent. That proof having been supplied the letter was admissible as prima facie notice to defendants of the plaintiffs’ claim as to the siding. Folsom v. Cook, 115 Pa. 539. Had it been post litem motam, it might have been regarded as an effort to make evidence in their own favor, but it was so nearly cotemporary with the written agreement, and so long before any appearance of delay in performance, that it cannot be held incompetent for such reason. Had it been a claim made in conversation between the parties there can be no doubt of its admissibility. Coming at the time and under the circumstances that it did, it stood upon the same ground. Its weight may have been very light, but that was for the jury.

The remarks already made as to the policy of permitting proof by parol of other terms than those in a written contract, apply with special force to that prolific source of dispute, litigation and too often of actual fraud, claims for extra work. But the rule that a written agreement may be subsequently modified or rescinded altogether by parol, is too well established to be overturned. The remedy for the abuse of it lies in the firmness of the trial courts in setting aside verdicts not founded on clear and satisfactory proof.

The fourth and sixth assignments of error are based on the view that the architect had found the value of the rosin not put under the floor. By the contract he Avas made the arbiter to decide all questions as to work omitted, etc., and undoubtedly he might have passed conclusively upon this one, of the value of the rosin not supplied. But it does not appear that he did so. His written finding on this point is an' item in the credits, “By amount retained until rosin filling is properly put under floors, or until ascertained by whose fault the rosin was not properly put under the same.” Prima facie this was not a finding of the value of the rosin, but a liquidation of defendants’ damages, and the amount of the credit they were entitled to on this item of the contract, if the failure of proper performance was not their fault. The latter question was left open, and was rightly submitted to the jury.

None of the assignments of error can be sustained.

Judgment affirmed.