delivered the opinion of the court.

There are fifty-one assignments of error noted in the abstract. It is impossible within the limits of an ordinary opinion and, considering the nature of some of them, unprofitable, to examine all these alleged errors. The essence of plaintiffs’ grievance, as stated, is that the city *205 entirely failed to comply with part of its contract and was dilatory in what it did perform. Without going into the elaborate detail which would be necessary in a minute consideration of the plaintiff’s numerous objections, we must content ourselves with some general observations upon the construction proper to be given to the contract involved.

1. Under its terms mere delay of the city constitutes no ground for damage. It only extends the time for the plaintiff to complete the work within the discretion of the engineer, for the contract itself stipulates thus:

“The contractor shall not be entitled to damages on account of delay, but if such delay be occasioned by the city the contractor shall be entitled to an extension of time in which to complete the work, to be determined by the engineer.”

2. It is provided in the specifications as follows:

“The city of Eugene shall have the right to make any changes in the plans, grades or lines that it may deem necessary, after the contract is awarded. If the changes diminish or add to the quantity of work to be done under the contract, the contractor shall be paid at the contract price for only the actual amount of work done, as herein specified.”

This furnishes the rule for compensation of the plaintiffs for increased work done on account of the alleged changes. True enough, it is said in the complaint that the defendant and its engineers frequently changed the lines and grades of the canal, thereby causing great loss of time and extra work, and required plaintiffs to increase the height of the embankment after the same had been completed according to contract. But whether that resulted in ten yards of excavation or fifty yards increased fill on the embankments is not stated. Such data as this are necessary in order for the court to determine the amount of compensation which should have been awarded to the plaintiff on account of extra work, if any was *206 required by reason of the changes made by the direction, of the defendant’s engineer.

3. The complaint blames the defendant for not furnishing plans in sufficient detail. The language of the contract in that respect is:

“The contract prices shall include all labor and expense necessary to complete the work according to the plans and specifications on file in the office of the city recorder of the city of Eugene, and to maintain it in good condition until accepted by the engineer.

Owing to the fact that the plans are not set out in the bill of exceptions, we are unable to construe them, and, if we were thus equipped, it is a sufficient answer to the contention of plaintiffs in this respect that if the delineations were not wrought out in detail enough to meet their approval they ought not to have engaged on such drawings to build the canal. According to their contract, these plans and specifications were on file in the office of the city recorder, a matter of public record which they could consult before undertaking the work. Then was the time to object to the sketches and require them to be worked out in greater detail. It is too late, after having signed the contract, to urge that objection.

4. The complaint says “that said defendant and its engineer failed, neglected, and refused to furnish either the said Manerud or these plaintiffs with either suitable or sufficient plans of said canal, such as are usually and customarily furnished in cases of like character; that it is necessary, usual and customary for the engineer in charge of the construction of work of the character of the proposed canal to cross-section the same at every station and to mark the side lines thereof with stakes or otherwise indicate thereon the depth of the excavation or the height of the fill before the work is commenced thereon; and the performance of the contract by the plaintiffs without such work by the engineer would be impossible.”

*207 5. By Section 727, L. O. L., “evidence may be given on the trial, of the following facts: * * (12) Usage to explain the true character of an act, contract, or instrument where such true character is not otherwise plain, but usage is never admissible except as a means of interpretation.” Usage or custom may be employed to explain, but never to add to or contradict, a contract. Holmes v. Whitaker, 23 Or. 319 (31 Pac. 705). If custom is to be pleaded as an element of plaintiffs’ case, it must be shown to be, among other things, general in the business involved and that it was either known to the party or of such general notoriety as to support the presumption that it was thus understood: Hendricks v. Middlebrooks Co., 118 Ga. 131 (44 S. E. 835) ; Norwood v. Alamo Fire Insurance Co., 13 Tex. Civ. App. 475 (35 S. W. 717) ; Lindley v. First National Bank, 76 Iowa 629 (41 N. W. 381: 2 L. R. A. 709: 14 Am. St. Rep. 254) ; Mobile Fruit & Trading Co. v. Judy, 91 Ill. App. 82; Sipperly v. Stewart, 50 Barb. (N. Y.) 62; Robinson v. New York, etc., Steamship Co., 63 App. Div. 211 (71 N. Y. Supp. 424) ; Rickerson v. Hartford Fire Insurance Co., 149 N. Y. 307 (43 N. E. 856).

The record discloses no statement in the pleadings, nor, so far- as the bill of exceptions shows, any evidence of knowledge on the part of the defendant of the alleged custom or any statement that it is of such general notoriety as would authorize us to indulge the presumption that the defendant was aware of or contracted with reference to it.

6. The plaintiffs complain of the conduct of the defendant’s engineer in making the estimates at the end of each month. The provision of the contract already quoted is substantially that a partial estimate shall be issued by the engineer at the end of each calendar month for the amount due the contractor for the work done during the month, *208 and the city shall pay to the contractor eighty per cent of such estimate, retaining twenty per cent until the completion of the work and its acceptance by the engineer. A fair construction of this stipulation is that it means the engineer shall be the arbiter of how much should be paid as the work progresses. It does not mean that all the excavation or other work shall be paid for in full, or even eighty per cent of the full price at the end of each month. Only a partial estimate of the work performed was required, and even then only eighty per cent of the incomplete appraisement was imposed upon the city as a payment. Otherwise a contractor might do the easy part of the work, and abandon the other at a profit on the whole transaction, although he was deprived of the remaining twenty per cent of the estimate. Plaintiffs have shown no cause of complaint under this clause of the contract.

There were sundry instructions given by the court, of which the plaintiffs complain, all relating to what would amount to an abandonment of the work by the plaintiffs or what would excuse them from the imputation of such fault. These become unimportant in view of the fact that the jury found the issue on that subject in favor of the plaintiffs and rendered a verdict against the defendant.

There are many other unimportant assignments of error, such as asking leading questions and receiving answers thereto, all of which are largely within the discretion of the court, apparently not abused in this instance. They are not sufficient, however, in our judgment to affect the result, and hence the judgment must be affirmed. Affirmed.