Opinion by

In the original affidavit of defence the defendants averred that they had a just and full defence for the whole of the plaintiffs’ claim, “ except the sum of $13,253.82, for which they tender judgment to the plaintiff in this action.” In the supplemental affidavit the defendants allege that they “ do not owe the plaintiffs on the bark peeled a sum in excess of $13,253.82, and this sum is payable only under the terms of the contract when plaintiffs shall convey all the bark on the lands aforesaid, at the cost price thereof, to the defendant, and this the defendants are now ready to do on the conditions aforesaid, and defendants are entitled to an abatement on said sum by way of damages arising from plaintiffs’ failure to perform his contract as aforesaid, in a sum exceeding two thousand dollars. The defendants have heretofore agreed and do now agree to pay the said sum of $13,253.82 on conveyance to them by the plaintiffs of the bark on the lands aforesaid at the cost price thereof.”

It will be seen that in both the affidavits the defendants admit that they owe the plaintiffs the distinct sum of $13,253.82 for bark delivered under the contract, and only claim to set off a sum exceeding two thousand dollars as damages for the non-conveyance by the plaintiff, Samuel Baugh, to them of all the bark on the plaintiffs’ other lands than the twelve acres which *638lie sold them. In support of the supplemental affidavit they contend that the expression in the contract, “ all bark is to be sold to the party of the second part at the cost price thereof,” means all the bark on all the other lands of the vendor in the neighborhood of the tannery and the twelve acres sold to the defendants. The contract between these parties is in writing and under seal. It contains no provision in reference to any other land than the piece sold. There is no stipulation in it for the sale of any bark on any lands other than the piece sold, and the bark on that piece which was still on the trees would necessarily pass with the fee simple of the land.

Moreover a sale of bark “at the cost price thereof,” implies that a cost price had already been incurred, and therefore the only bark to which such an expression could be applicable would be bark which had already been peeled. We can readily understand how there would naturally be a quantity of bark on a tannery property at all times, and as the purchaser of the property would necessarily require the bark for use in his tanning operations he would need some stipulation as to its price in his contract of purchase. We see no occasion for extending, by construction merely, this natural and proper meaning of the contract in this case so as to embrace bark on other lands to which no reference whatever is made in the contract, and which had never been peeled. The affidavits of defence contain no averments which would suffice even to raise a question as to any alteration or change in the written terms of the contract. No allegation of fraud, accident or mistake, in its preparation or execution, is made, and without such allegations there is no question to be submitted to a jury touching the terms of the contract. These are in writing and must be interpreted exclusively by the court. Upon the reading of the contract we are clearly of opinion that it must be adjudged by its own expressed terms, and also that these do not include any other bark than such as had already been peeled and was then on the premises sold. It is not by any means sufficient for one party to a contract to aver that it was understood to embrace matters which are not expressed in its language. The rule which permits written contracts to be changed by parol is far more strict than any such loose method of impeachment would imply. The conditions upon which such changes may be made have been *639frequently expressed, and carefully defined, by decisions of this court. It is sufficient to say that in the present case not one of them appears in either affidavit. We consider that upon these affidavits of defence the plaintiffs were entitled to have judgment entered in their favor for the full sum admitted to be due, to wit, $18,258.82, and when they entered judgment for only $11,000 they were clearly within their legal right. It follows that the learned court below was in error in striking off the judgment entered in favor of the plaintiffs and in staying the execution issued thereunder.

The order of the court below is reversed, and the judgment for eleven thousand dollars entered in favor of the plaintiffs and the execution issued thereon are reinstated at the cost of the appellees, and the record is remitted for further proceedings.