Mileeje, J.,
delivered the opinion of the Court.
There are errors in the rulings of the Court below requiring a reversal of this judgment, and as the case is to be sent *202back for another trial, it is essential to settle the true construction of the contract for the sale of the farm, the only-matter of dispute between the parties., This contract being in writing, effected by means of letters, its construction is to be declared by the Court, and should not be submitted to the finding of the jury.
The offer contained in the letter of January 11th, 1864, from the vendee to the vendor, is in these words: “ I now offer $11,000 for said farm as it is, including the wheat in the ground * * * the farm to be paid for as follows: when the premises are cleared and the deed made and recorded, with searches of docket, and handed over to me free of cost, I will pay over $1000, and will give my due bill or surety for balance, after deducting my claim, to be paid in all, January, 1865; neither party to charge' or claim any interest,” as expressed in one part of that letter, and in another, “ that there may be no misunderstanding, I repeat the terms of payment, $11,000 purchase money, to be paid when deed is made and searches handed over free of costs and possession given, $1000 cash, the balance, after deducting my claim, to be paid during January, 1865, this to include wheat in the ground, neither party claiming or requiring interest.” The purchaser held a mortgage on the farm executed in April, 1861, for $6,500, bearing interest from the 22d of February, 1861, and the vendor was also indebted to him upon a draft for $124.64, and upon open account the items of which are undisputed. The appellee contends that all interest on the mortgage debt, the draft and the open account is relinquished, whilst the vendee insists he is entitled to interest on the whole, down to the date of the consummation of the contract, by acceptance of this offer. Neither view is correct, as will be presently shown by an examination of the whole negotiation and correspondence preceding the offer and its acceptance. The former overlooks the true meaning of the terms “after deducting my claim,” whilst the latter does violence to the stipulation that “neither party” shall “charge or claim any *203interest.” The previous letters show that the vendor, who was the step-mother of the purchaser, had been for some time anxious to sell her farm and relieve herself from debt; that as early as the spring of 1863, negotiations had been going on, and offers had then been made for it by the present vendee. On the 11th of August of that year, she wrote requesting him to let her know how much she owed him, or how much interest she must pay him, and how much he would take for his mortgage, so that she might know just what price she could afford to take for the farm, as she had heard of a party who might purchase; and also asks him to write the best he could do, as he seemed to decline doing what he had offered to do last spring. To this he replied by letter of the 24th of August, enclosing his account, in which he charges interest on the mortgage debt from the 22d of February, 1861, to the 1st of August, 1863, and interest on the draft to the same date. These are the only charges of interest, which amount to $972.50, and the whole amount of the account thus stated is $7,579.74. In the letter enclosing this account he says: “I can’t enclose you your whole account, every thing as if you were a stranger, and if you could make a good sale we might ask you for the most of. it; if you have a moderate offer we will try to be as moderate, or even more so;” expresses his disinclination to buy, but states he has not refused or declined to make good any offer of last spring, which is about the best he could do. The next letter is that of the 11th of January, 1864, containing the offer, the terms of which have already been stated. In this he states that he revokes all former offers, and now makes this his last and best, only because of the relation in which he stood to her, as he knows he was paying some $3,000 more than he believed the farm to be worth; that he would not give more than $8,000 or 9,000,to a stranger, even if he wanted to buy, and that he bought now to help her condition and not his own. After receipt of this, and before accepting the offer it contained, she again wrote by letter of *204the 14th of January, (misdated, according to the proffered testimony, the 14th of February,) in which she says she does not understand what he meant in his letter of the 11th, “ by saying neither of us shall claim any interest: when I give possession and a deed are you not then paid ? You are making the interest on the farm for the money that will be due me; you surely will not be so hard with me, unless you will throw off some of the interest due you ; ” that she had been reproved for not trying to sell sooner, and that many persons had said he intended to put her off “ until the interest eats up the farm,” &e., but “she had waited patiently as possible and trusted on, encouraged by his kind words; that one of his letters had stated he ‘would throw off a good deal of interest;’ please make the sum $7,000, then when my debts are paid I will not have $1,000 left; indeed it will be little more than poorhouse allowance,” &c. In reply to this he writes by letter of the 20th of January, in which, after acknowledging receipt of her’s of the 14th inst., he says she does not say by it whether she will or will not accept his offer; “ if you do accept it I will try to comply with my promise; if you do not accept it, and will sell to others, and I hope at better rates, I will deduct $500 from my claim on the payment of the money, which is some evidence I do not want the interest to eat up the farm; ” he then expresses his indignation at those who may have charged him with sinister motives in the matter, and tells her to sell the farm to them; that he thinks he has offered from $2,000 to $3,000 more than it is worth to him, for the sake of her and her’s only, and that much more than he would give to strangers, even if he wanted to buy, and therefore he “could make no better offer.” After this she wrote another letter, which he received on the 25th, in which she states that though she had not' accepted, she had not refused his proposal, and says: “ I only want to beg a little better bargain; the $1,000 I must pay away to my children, and pay them interest for the balance, and you know it is hard to pay interest on what I owe and not get any on what *205is coming to me, nor will I have one dollar to live on for one year, whatever may befall me; you did not bind me to any set time, I consider you have made the offer in the way that allows a reasonable time to make up my mind; please allow me a week or a little more, and I will send it in; my case is desperate and my doom is sealed, and only waits for you to sign my death warrant; for God’s sake answer this as soon as possible and say just what your claim shall be if I accept your terms. I appeal to your mercy, yon that have given away so much money, and to many that were less deserving than I. I hope this may be the last time I shall ever ask mercy from any but God. I repeat, please answer this immediately and do not keep me in suspense, for it has almost broke my heart.” Before receiving any reply to this she directed Mr. Archer to write the letter of the 26th of January, substantially accepting the offer, and on the 28th of January, also wrote herself fully accepting that offer, in case he had not received the letter of Mr. Archer to the same effect. On the same day, the 28th, he wrote to Mr. Archer acknowledging receipt of his of the 26th, admitting it to be an acceptance of the offer.
This correspondence removes all obscurity and uncertainty that may have hung over the controverted clauses in the letter of the 11th of January, 1864. In our opinion, it is perfectly clear the “claim” to be deducted is the claim of $7,579.74, sent to the vendor in August, 1863, and in her possession when the offer in question was made, and the clause, “neither party to charge or claim any interest,” means that no interest should be charged on that claim, and that the vendor was to have none on the deferred instalment of the purchase money. By this construction, effect is given to every clause and word of the offer, and a fair and reasonable interpretation given to the contract. The vendee relinquishes interest on his mortgage debt and on the draft beyond the 1st of August, 1863, and agrees to charge none on the other items of his account, and the vendor consents to claim none on the balance due her to be paid in Jan*206uary, 1865. The whole tenor of the correspondence clearly discloses this to have been the intention of the parties at the time the contract was made. That the vendee never supposed he had waived all interest on his mortgage debt, is too plain to admit of question, and however much our feelings and sympathies may be enlisted in behalf of the vendor by her distressed condition and pathetic appeals to him from whom she thought herself entitled to ask and receive more favorable terms, we cannot convince our judgments that she, at any time before the offer was accepted, ever interpreted it as going to the extent she now insists upon. These very appeals themselves constrain us to this conclusion, for if she had understood the offer as abandoning all claim to any interest on this large mortgage debt, they show she would have accepted it without hesitation, because that gave her more than the utmost she afterwards vainly implored from the mercy of her creditor.
No rule of evidence is infringed by resorting, as we have done in our construction of this contract, to all the written correspondence, as well that which preceded the offer as that which preceded its acceptance. The terms, limitations and conditions of the contract must, it is true, be found in the letter of the 11th of January, and these are perfectly intelligible, as stated on the face of that letter. One of the essential conditions, however, there found is, that the vendee’s claim shall be deducted from the purchase money, but as to what that claim is in amount, and of what items it consists, the latter itself is silent; and this must, of necessity, be ascertained by evidence de hors. The case, therefore, on this point, falls within the general rule that, as to the parties or 'subject-matter of a contract, extrinsic evidence may and must be received and used to make them certain, if necessary for that purpose. The contract must be applied to its subject-matter by evidence from without. Looking to this evidence, (which, in this case, is in writing,) we clearly discover that claim to be in amount and items that which had been *207sent to the vendor in August, 1863, and this being settled, the meaning of the clause relating to interest is at once removed from every shadow of uncertainty; the whole contract becomes entirely plain in force and application, and substantial effect is given to every clause and word. The rule that parol or extrinsic evidence will never be permitted to contradict or vary the terms of a written contract, is certainly a cardinal one, resting upon the fundamental principle that the law will not allow a contract to be made for parties different from that which they have made for themselves, but it is equally a certain and indisputable rule that such evidence is admissible to ascertain and make certain the parties and subject-matter of an agreement, to apply the contract to its subject, to prove any collateral, independent fact about which the written agreement is silent, to remove what are termed (and often inaccurately termed) latent ambiguities, and as this) Court has said in McCreary vs. McCreary, 5 G. & J., 157, quoting from Phillips on Evidence, “though an ambiguity, apparent on the face of a written instrument, cannot be explained by extrinsic evidence, yet, when a question arises as to the general intention of the parties concerning which the instrument is not decisive, it has been held that proof of independent facts, collateral to the instrument, may bo properly admitted.” In all cases of this kind, such evidence is used, not to contradict or vary the written instrument, but to aid, uphold and enforce it as it stands. Authorities, of which a multitude exists, need not be cited to sustain propositions so wrnll settled and familiar as these. We cannot, however^ forbear a reference to 2 Parson’s on Cont., 548, where an illustration, peculiarly apposite to the case before us, of the application of these rules, is thus put: “ If a negotiation be conducted in writing, and even if there be a distinct proposition in a letter and a distinct assent making a contract, and then the parties reduce this contract to writing, and both execute the instrument, this instrument controls the letters, and they are not permitted to vary the force and effect of the in*208strument, although they may be sometimes of use in explaining its terms.”
We now,, proceed briefly to dispose of the questions presented by the several rulings to which exceptions were taken:
1st. The parol proof in the first exception, to the effect that the farm was worth $15,000 or $16,000 at the date of the purchase, is clearly inadmissible. The price to be paid for the land is definitely fixed by the contract at $11,000, and if this testimony does not directly contradict the agreement in this respect, it is for every other purpose entirely irrelevant. It furnishes no aid in explaining or interpreting any part of the contract, even if it should for a moment be conceded to be admissible for that purpose. It should have been rejected.
2d. The letter from the vendor, excluded in the second exception, ought to have been admitted in evidence upon proof that it was written on the 14th of January, was received by the vendee on the 20th of that month, and by mistake was dated the 14th of February. It is one of the series of letters written, as is apparent on its face, and from the letter of the purchaser in reply thereto before acceptance of the offer, and, as we have already decided, is to be considered in the construction of the contract. There is no difficulty in allowing the mistake as to its date to be established and corrected by parol proof. Deakins vs. Hollis, 7 G. & J., 311; 2 Parson’s on Cont., 554.
3d. The ruling in the third exception is correct. Where an offer is made by letter, an acceptance by written communication takes effect from the time when the letter containing the acceptance is mailed, and not from the time when it is received by the other party. Such is now the settled doctrine of both the English and American authorities, and was so decided by this Court in the case of Wheat vs. Cross, 31 Md., 103. See, also, Adams vs. Lindsell, 1 Barn. & Ald., 681; Dunlop vs. Higgins, 1 House of Lords Cases, 381; 1 Parsons on Cont., 406, note (h.) This contract was, therefore, closed as early, at least, as the 28th of January, and the *209excluded account, charging interest on the claim for $7,579.74 from the 1st of August, 1863, down to the 31st of January, 1864, was not rendered and sent to the vendor until the last-named day, and, consequently, after the contract was completed. It is well settled that a Court cannot be aided in the construction of any agreement by the acts which the parties may have done under it, nor is a party bound by any construction which he may have put on the instrument, (Ringgold vs. Ringgold, 1 H. & G., 74; Hutchins vs. Dixon, 11 Md., 40; and, a fortiori, the acts done by one party after the completion of the contract in furtherance of his understanding of it, cannot bind the other party, or be admissible in aid of its construction.
4th. The defendant’s prayer was properly rejected, if for no other reason, because it failed to instruct the jury down to what period they should allow interest on the mortgage debt. As we have shown, interest is to be allowed on this debt only to the 1st of August, 1863, as stated in the account sent to the vendor in that month.
The two instructions given by the Court, as well as that granted at the instance of the plaintiff, were open to the objection that they left to the jury the construction of the contract, which was a question of law to be decided by the Court; but it does not appear from the record that any such objection was taken at the trial, and in such case this Court cannot, since the Act of 1862, ch. 154, consider the instructions defective for that reason. But, whether construed by Court or jury, the contract must be interpreted upon the same evidence and by the same rules, and, as we have before said, it was error to tell the jury that, in considering its terms, they must confine themselves to the letter of the 11th of January, and its acceptance by the letter of Mr. Archer, and to allow them to find that the offer contained a waiver of all interest on the debt due the defendant, as was done by the' instructions which the Court gave. The rule that the offer is to be construed most strongly against the party making it is one of strictness and *210rigor, to be resorted to only when all other rules of exposition fail.- We have shown there is no necessity in this case for its application, and the plaintiff’s prayer, which adopts it as applicable to this contract is, for that reason; erroneous, and should have been rejected.
(Decided 4th March, 1870.)
Judgment reversed, and, new trial awarded.