1. A considerable number of the assignments of error are based upon the contention that the court never acquired jurisdiction of the person of *391the defendant, and all of these may be considered together. At the outset it must be observed that the defendant has filed an answer upon tFe merits, which, according to a long line of decisions of this court, constitutes a voluntary appearance and a waiver of any defect in the service of summons. Among these are: Rogue River Mining Co. v. Walker, 1 Or. 341; Harker v. Fahie, 2 Or. 89; White v. North West Stage Co., 5 Or. 99, 102; Kinkade v. Myers, 17 Or. 470 (21 Pac. 557); Belknap v. Charlton, 25 Or. 41 (34 Pac. 758); Fildew v. Milner, 57 Or. 16 (109 Pac. 1092). The case of Belknap v. Charlton, 25 Or. 41 (34 Pac. 758), may be regarded as the leading case upon the subject in this jurisdiction, having been many times cited with approval, the latest being in Felts v. Boyer, 73 Or. 83 (144 Pac. 420), and Roethler v. Cummings, 84 Or. 442 (165 Pac. 355). In the case of Belknap v. Charlton, 25 Or. 41 (34 Pac. 758), Mr. Justice Bean says:
“It is claimed by the plaintiffs that while a defendant may appear specially to object to the jurisdiction of the court over him on account of the illegal service of process (Kinkade v. Myers, 17 Or. 470 (21 Pac. 557), he must keep out of court for every other purpose, and that any appearance which calls into action the power of the court for any purpose except to decide upon its own jurisdiction, is a general appearance, and waives all defects in the service of process, and many authorities are cited to sustain this position. The principle to be extracted from the decisions on this subject is, that where the defendant appears and asks. some relief which can be granted only on the hypothesis that the court has jurisdiction of the cause, and the person, it is a submission to the jurisdiction of the court as completely as if he had been regularly served with process, whether such an appearance by its terms be limited to a special purpose or not. * * This seems to be a reasonable rule, and one which will adequately protect the rights of the parties, and *392it- determines the effect of defendant’s appearance from the nature of the relief which he seeks to obtain. If he asks the court-to adjudicate upon some question affecting the merits of the controversy, or for some relief which presupposes jurisdiction of the person, and which can be granted only after jurisdiction is acquired, he will be deemed to have made a general appearance, and to have submitted himself to the jurisdiction of the court, and cannot, by any act of his, limit the appearance to'a special purpose.”
In the present case, the defendant appears to have acted upon the theory that since the amendment of Section 74, L. O. L., General Laws of Oregon for 1911, page 144, a plea in abatement, challenging the jurisdiction of the person may be joined with a plea to the merits without effecting a waiver of defects in the service of the summons.. But this does not follow. It is true, that when the defect in the service does not appear upon the face of the record, it may be called to the attention of the court by a plea in abatement, and it is also true, that in all proper cases the plea in abatement may be joined with other defenses and counterclaims in the same answer, but there is nothing in the statute which tends to neutralize the established legal effect of pleading to the merits, which is, that it is a voluntary submission to the jurisdiction of the court. From the moment that defendant filed its answer there was no further question of jurisdiction left' in the case.
Turning then, to the questions arising upon the trial upon the merits, the defendant first urges that the court erred in excluding from the consideration of the jury two letters which were identified as exhibits “0” and “D” and also the substance of a telephone conversation between the secretary of the defendant and the president of the plaintiff. These three as*393signments are here grouped together for the reason that they present the same problem. The two letters, in their order, are as follows:
Exhibit “C.”
‘'April 5,1917.
“Duncan Lumber Co.,
“Northwestern Bank Bldg.,
“Portland, Oregon.
“Gentlemen:—
“We are in receipt of yours of the 3rd inst. requesting return of blue sheet acknowledgment of your order #1400. This order came into the office' during the writer’s absence in the east. Last week he called at your office and talked with Mr. Duncan regarding date of shipment mentioned in your letter.
. “In the first place we wish to state we cannot accept this order as it stands and complete shipment before next fall. We are willing to accept a portion of it and buy what we can from neighboring mills, making the best shipment possible, but we are not willing to go on record with a definite promise of delivery.
“We wish you would call us by phone and talk this matter over with ns or write us fully how you wish us to handle it.
“Yours very truly,
‘ ‘ Willapa Lumber Company.
“Jayne,
“Secretary.”
Exhibit “D;”
“April 9, 1917.
“File: Order #1400.
“Willapa Lumber Company,
“Raymond, Washington.
‘ ‘ Gentlemen:
“Attention Howard Jayne, Sec.
“Referring to your letter of April 5th, and confirming phone conversation, kindly let us have return acknowledgment of our order above numbered to complete our files and please do all that you possibly can toward getting this material ready for shipment. As *394soon as you have any of this material ready for loading, order car, showing on the face of your car order:
“ ‘Material for the Construction of System Cars— Order Duncan Lumber Company ’
and send us a copy of this car order and we will give the matter of having equipment placed at your plant, immediate attention.
“I hope that you will give this order the vigorous attention that it demands, and with best wishes, remain
“Yours very truly,
“Duncan Lumber Company.
“Gr. M. Duncan,
“President.
“Cars furnished as above must not be diverted to other loadings.”
In regard to the telephone conversation, which was excluded, the defendant’s secretary, Jayne, was permitted to testify as follows:
“Well, as I understood, it was practically agreed between us that we were to furnish what we could and buy from neighboring mills when we could, and Mr. Duncan was to buy the rest outside. That is the reason I signed the order.”
The order, which was signed by Jayne after the exchange of the foregoing correspondence, and after the telephone conversation above referred to, and which is the foundation of plaintiff’s action, reads as follows:
“#1400.
“Portland, Oregon, Mar. 22nd, 1917.
“To Willapa Lumber Company, Raymond, Wash.
“Ship to Duncan Lumber Company, Minnesota Transfer, Minn.
“Route-N. P.
“It is understood, unless otherwise specified, that all lumber shipped on this order will conform to the standard classification, grading and dressing rules adopted by the West Coast Lumber Manufacturers’ *395Association and is guaranteed not to exceed Association weights.
“Load all cars to capacity in accordance with railway tariffs governing, and make proper notation on Bill of Lading to protect actual weight of contents. Any excess freight charges resulting through your failure to do this will be for your account.
“Prices attached are f. o. b. cars Pullman, 111.
“Terms — Regular. (Prices include 5% commission to us.)
B. & B. tr. Spruce Refrigerator Car Lining Strips, Kiln Dried $42.00
6.500 ft. 1x6"— 6' S 2 S to 13/16", edges rough.
7.000 “ “ 9' do.
19,500“ “ 14' “
B. & B. tr. Spruce Refrigerator Car Lining, Klin Dried, $42.00.
39.000 ft. 1x6" — 5' S 2 S T & G to 13/16x5^" face.
12.500 “ “ 6'6" do.
91.000 “ “ 9' “
16.000 “ “ 12* «
128.000 “ “ 14' *•
112.000 “ “ 16' «
As per Sketch ‘C’ B/P #114-1400.
“Shipment: Commence promptly and complete by May 15th, to 30th, 1917.
“Note: When ordering cars show on requisition ‘Material for Duncan Lumber Co. for construction Northern Pacific System Refrigerator Cars — final destination Pullman, 111.,’ and send us copy of your car order. Special arrangements will be made to furnish cars promptly when so ordered.
“Confirming phone conversation with Mr. Jayne.
“This order accepted and will be shipped.
“Willapa Lumber Co.
“By Jayne.
“Our Order #1400.
“Sign and return to us at Portland.”
2. It is the contention of = the defendant, as disclosed in its answer and in the argument upon this appeal, that the time contract between the parties is to be found in the two letters and the foregoing order. Neither fraud nor mistake is alleged. An inspection *396of the order discloses that it is, on its face, a complete contract. It does not appear that any necessary detail is omitted which should be supplied, nor is it contended by the defendant that the letters and telephone conversation supply additional details, but that they modify the terms thereof. In other words, defendant seeks, by these offers, to establish, by evidence dehors the contract, that prior to its execution there .were negotiations wherein it was agreed that the terms of the contract, both as to quantity of material and as to time of delivery, should be different from those expressed in the instrument subsequently signed by the defendant. That' this cannot be done, is so clearly taug’ht in Sund & Co. v. Flagg & Standifer Co., 86 Or. 289 (168 Pac. 300), that it requires no further comment. The evidence was properly excluded.
3, 4. It is then urged that error resulted from the action of the court in admitting evidence of the expense incurred by the plaintiff in purchasing lumber elsewhere, after plaintiff’s failure to deliver the same. It is the settled law of this state, as conceded by the parties hereto, that the measure of damages for failure to deliver merchandise, in accordance with a contract of purchase, if the articles have a market value, is the difference between the contract price and the market value at the time and place of delivery. But there is another doctrine, equally well founded, to the effect that while the purchaser is not required.to go into the market and purchase the goods elsewhere before bringing his action, he may, if he see fit, do so, and if, in a successful effort to minimize the damage, he incurs expense, he is entitled to recover such expenditures as an element of damages, so long ag the total recovery does not exceed the difference between ■the contract price and the market price of the mer*397chandise which the defendant failed to deliver in accordance with the terms of his agreement: 8 B>. C. L. 450. In the present case the trial court submitted such evidence to the jury under the following instruction:
“Yon are further instructed, however, that if you also find that plaintiff in this case was able to buy some or all of the lumber not delivered under the contract at less than the market value, then you are to allow the plaintiff as damages only the amount of its actual loss; that is, the difference between the contract price and the price plaintiff had to pay to replace the order; * # but in that case you must also take into consideration and compensate plaintiff for the necessary and reasonable expenses plaintiff was obliged to incur for salaries and railroad fares of employees, and telegrams and telephone charges in connection with replacing the order, as alleged in plaintiff’s complaint, and not to exceed the amount stated in said complaint. But you must bear in mind that the total damages which you may allow in any event for any lumber not delivered under the contract must not exceed the difference between the contract price and the market value at the time of the breach at the place of delivery, * * nor shall such damages exceed the amount demanded in the complaint.”
There was evidence submitted to the jury to the effect that the market value at the time of the breach, at the place of delivery was $75 per thousand feet, but that plaintiff purchased some of it at $61 and $66 and that the total loss to plaintiff, exclusive of his expenses, was reduced to $7,520.27, while at the market value, it would have amounted to $11,928.18. In this state of the record, it was not error to admit the evidence of which complaint is made.
It is urged that it was error to permit two of plaintiff’s witnesses to testify that at the time of the alleged *398breach, which according to plaintiff’s contention, was August 17, 1917, airplane spruce had a market value of $105 per thousand feet; that the spruce which plaintiff purchased was not airplane spruce, but was an inferior and cheaper grade of material. The answer of the witness Duncan upon this subject was:
“The prevailing market at that time on airplane spruce was established at $105 per thousand feet, and naturally in establishing the price for airplane spruce, that had something to do in establishing the market on all spruce.”
The witness Shaw testified thus:
“Q. Mr. Shaw, I will ask you if you boys had difficulty to purchase spruce? •
“A. Yes, sir. On my first trip to the Harbor I took this spruce up with every mill whose manager wan at home at that time, and was unable to buy any of it at any price. The answer that I got to my request for shipment of the spruce was that they could not cut it without going into their airplane stock; consequently they couldn’t furnish it except at practically airplane prices.
“Q. And what were those prices?”
“A. The price at that time was $105 for airplane material. ’ ’
5. Defendant moved to strike this out, as immaterial and irrelevant, which was denied. The manifest effect of this evidence went no further than to explain the prevailing high price of all grades of spruce, and therefore could have worked no harm to defendant.
6, 7. Our attention is also directed to the fact that the alleged contract upon which plaintiff stands, fixes May 30th as the final date of delivery, and it is insisted that there is a total failure of proof of any agreement to extend the time of performance, and that therefore it was error to admit evidence of the market *399value of the material at any other date. The only evidence upon this subject is that of the witness Duncan, who says that after shipments under the order should have been moving, but were not moving, he was in frequent communication with defendant in regard to the delays and urging delivery, receiving promises which were not fulfilled, and finally on August 18, 1917, he received a letter from defendant notifying plaintiff that no more material would be delivered. It also appears that the last delivery was made on July 9th. While the testimony of Duncan is somewhat vague and general in its nature, when it is. taken in connection with the fact that a delivery was made on July 9th, and accepted, we are obliged to conclude that there is evidence, in the acts of the parties, of an agreement to extend the time of delivery, and the fact that a letter was written by defendant on August 17th, declining to make further deliveries was properly submitted to the jury in fixing the date of the breach.
Complaint is made that the court erred in permitting the plaintiff, upon rebuttal, to introduce evidence of three individual sales of similar lumber to other parties, in the months of April, August and December respectively, at the price of $75 per thousand feet. It is urged that this evidence was not properly evidence in rebuttal, and that the dates do not correspond with the date of the alleged breach of the contract, and that such evidence was therefore incompetent.
8, 9. An examination of the record discloses that the defendant offered evidence of individual sales over a period of time ranging from June 11th to September 1st, and the evidence referred to in the assignment of error was offered to meet the same. It is true that the evidence was designed to prove the original cause *400of action, and was not properly in -rebuttal, and so the action of the court amounted to a reopening of the case for plaintiff. This is a procedure regulated by the sound discretion of the trial court, and not reviewable here in the absence of manifest abuse, which we do not discover. The evidence upon the subject of market value was allowed to take a wide range upon the part of both litigants, but throughout the entire trial the value at the date of the breach was emphasized, so that we think the jury was not misled thereby. Indeed, the verdict is for a sum slightly less than the amount which witnesses for plaintiff testified was actually paid for the material in replacing the order in August.
It is also contended that the court erred in permitting the plaintiff, during the trial, to amend its complaint by adding thereto a demand for interest, and submitting to the jury the question of interest. This question is settled beyond further discussion in this state, in favor of defendant’s position. The subject is very fully discussed in Sargent v. American Bank & Trust Co., 80 Or. 16, 42 (154 Pac. 759, 156 Pac. 431).
Our attention is called to what defendant insists is an erroneous instruction given by-the court as follows:
“Now, the first question for you to determine is whether or not there was a breach of the alleged agreement between the parties. If you find that there was a breach, then the next question for you to determine would be the amount which you would allow, if any, would be such as you would agree upon according to the evidence introduced in this case.
“Now, it will be impossible for you to arrive at the amount, if you have occasion to estimate it, with mathematical accuracy. Simply do the best you can, according to all the evidence that has been introduced, and allow some sum,' anywhere from one cent up to the *401full amount claimed by the plaintiff, if you allow anything. ” ,Messrs. Welsh & Welsh and Messrs. Angelí & Fisher, for the petition. Mr. J. G. Arnold, contra.
• Defendant argues that it assumes that there is a contract to be breached, and that this is one of the crucial questions in the case. This contention is disposed of already, in the consideration of defendant’s offer of evidence relating to negotiations prior to signing the order upon which plaintiff relies.
11. It is also urged that this instruction permits the jury to indulge in speculation in reaching the verdict, but in directing the jury to do the best they can, ‘£ according to all the evidence that has been introduced,” the charge clearly limits their consideration to the evidence submitted and is not vulnerable to the criticism aimed thereat.
The error in submitting the allowance of interest to the consideration of the jury, is simplified by the fact that the verdict segregates the interest, fixing it in the sum of $185. The judgment will therefore be modified by eliminating the sum of $185, awarded as interest, and the judgment is otherwise affirmed.
Modified.
McBride, C. J., and Burnett and Harris, JJ., concur.