delivered the opinion of the court:
^ It is insisted by appellants that the .words, “All sales subject to strikes and accidents,” printed at the top of their letter-heads, must be considered in determining what the contract was, and that said words constituted an express condition that became a part of the contract between them and appellees. We do not so understand the case. Under date of March 1, 1889, appellees invited appellants to make them an offer of sale of a specified quantity of sheet-iron, to be delivered in certain designated months. On March 4 appellants made them an offer, as requested. On March 9, in their letter of that date, appellees declined to accept the offer received, and at the same time they submitted for consideration an offer of their own,—an offer of purchase. This offer contained all the elements and terms of a precise and complete contract, and lacked only the assent thereto of the» persons to whom it was addressed to make it such a contract. The offer was to buy a certain quantity of sheet-iron, of certain sizes, to be delivered in Chicago in specified quantities and at designated times, and to pay therefor certain prices at certain stated times, and appellees concluded their proposal by saying, “If you accept our offer you may enter us for March shipment 250 bundles,” etc. The offer was absolute and positive, and without any conditions, qualifications or exceptions whatever. On March 11, appellants wrote to appellees : “Tour favor of March 9 at hand. We accept your offer.” And they thereupon proceeded to restate in their letter the terms of the proposal made to them. These two letters made the contract between the parties. The two preceding letters seem to us to be wholly immaterial. The mere fact that appel*109lants wrote their acceptance on a blank form for letters, at the top of which were printed the words, “All sales subject to strikes and accidents,” no more made those words a part of the contract than they made the other words there printed, “Summers Bros. & Co., Manufacturers of Box-annealed Common and Refined Sheet-Iron,” a part of the contract. The offer was absolute. The written acceptance which they themselves wrote was just as absolute. ’ The printed words were not in the body of the letter or referred to therein. The fact that they were printed at the head of their letter-heads would not have the effect of preventing appellants from entering into an unconditional contract of saleN
In American Express Co. v. Pinckney, 29 Ill. 392, this court said: “In a case where the agreement is partly written and in part printed, the preference is always given to the written part. ” In that case the printed matter was in the body of the instrument, incorporated and mingled with the written matter. It would seem there is more reason and occasion for applying the principle of law there invoked in a case where, as here, the words in print are separate and apart from the writing that appears upon the paper, and in a place where one would not be likely to look for limitations upon that which is written. People ex rel. v. Dulaney, 96 Ill. 503, is to the same effect as the case above cited.
When an instrument is in part written and in part printed, and these parts are apparently inconsistent, or there is a reasonable doubt upon the sense and meaning of the whole, the words in writing will control, because they are the immediate language and terms selected by the parties themselves for the expression of their meaning. (Alsagu v. St. Katherine’s Dock Co. 14 M. & W. 796, and Bobertson&Thomasson v. French, 4 East, 360, both cases cited with approval in Express Co. case, supra.) In the case at bar it is inconsistent that the contract should be both an absolute contract and a conditional contract. The terms *110of payment in this contract were sixty days’ time or two per cent discount for cash in ten days.. Suppose the words, “All sales not paid for on delivery to draw interest,” had been printed on the letter-head; can there be any doubt that the written terms would have controlled the printed words? Here there was a written provision that the iron was to be delivered free on board the cars at Chicago. Suppose it had been printed on the letter-head that the manufacturers would not be responsible for iron after a delivery to a common carrier; would not the written provision have governed the contract?
Upon the whole, we are inclined to the opinion that the mere fact that the words in question were printed in the caption of the paper on which appellants wrote their unqualified acceptance of the contract proposed by appellees, did not have the effect of reading them into the agreement thereby consummated; and appellants understood that some sort of an agreement was brought to a completion by their act, for in their letter they wrote : “We also enter your order for 250 bundles, etc., March shipment.”
Appellants make a further claim that there was an implied condition in the contract, that would relieve them from performance if their mill plant, without any fault on their part, was so disabled as to make it impossible for them to make the iron that they contracted to deliver. The contract did not call for iron manufactured at their mill. It simply called for first-class common sheet-iron of certain specified sizes. There was nothing to prevent their filling the contract by going into- the market and buying sheet-iron manufactured at other mills. Appellees seem to have experienced no difficulty, other than that of being forced to pay a higher price, when they went on the market and bought from other parties the sheet-iron contracted for which appellants failed to supply. But even if the contract had been for sheet-iron of their own manufacture, the breakages in this mill would not have relieved them from liability. The general doctrine *111is, that where parties, by their own contract and positive undertaking, create a duty or charge upon themselves, they must abide by the contract and make the promise good, and either do the act or pay the damages. (Steele v. Buck, 61 Ill. 343; Dehler v. Held, 50 id. 491; Bunn v. Prather, 21 id. 217.) Inevitable accident affords them no relief, for they are regarded as insurers to the extent of making good the loss. There is a principle of the law that, in contracts in which the performance depends on the continued existence of a given or specified person or animal or thing, a condition is implied that the impossibility of performance arising from the perishing of the person, animal or thing shall excuse the performance. But there is no place in this case for the application of that rule.
There is no doubt of the correctness of the rule stated by appellants, that where delivery is required to be made by installments, the measure of damages will be estimated by the value at the time each delivery should be made. In the case at bar, appellees made threats to buy in at seller’s expense, but excuses rendered and promises made by appellants of frequent and large shipments deterred them from doing so. If delivery is postponed by agreement between the parties, the measure of damages is the difference between the contract price and the market price at the time the article is deliverable by the subsequent agreement, and where the time of delivery is postponed indefinitely, the measure of damages is the difference between .the contract price and the market value at a reasonable time after demanding performance. Appellees admit that they had no legal right to buy in, during the month of August, more than 3159 bundles of sheet-iron, that being the quantity then due, under the original and additional contracts, on August 1. But the uncontroverted evidence is, that the price of such iron remained firm during September and a part of October, being at no time lower than August prices. So the premature purchases worked appellants, no injury, but were *112to their benefit. Besides this, it was held in Follansbee v. Adams, 86 Ill. 13, that the vendee may charge the vendor with the difference in prices without making any purchases, the result being the same, and the vendee being entitled to the benefit of his contract.
It is urged that the trial court committed error, in that it refused to allow to go to the jury testimony tending to prove that in June, 1889, one Charles, purchasing agent of appellees, made certain admissions to one of the appellants. There was no error in this action of the court. The admission of such testimony would have been in violation of the rule that the terms of a written contract cannot be varied by parol evidence, and also in violation of another rule, that the statements of an agent are admissible only when they are part of the res gestee, and are made dum fervet opus.
The making of the written contracts being admitted at the trial, the court having construed them and held that the printed line in the caption of the letters was no part of such contracts, and having resolved, as matter of law, that there was no implied condition in them, growing out of their nature, the claimed deficit in the deliveries not being denied, and there being no conflict of testimony in respect to the state of facts upon which the damages were to be based,"there remained in the case no question that required submission to the decision of the jury, and it was not manifest error to direct a verdict for the plaintiffs, and instruct the jury at what amount to assess the damages.
Some minor points of objection are raised, but in them we find no reversible error.
The judgment of the Appellate Court is affirmed.
Judgment affirmed.