delivered the opinion of the Court.
Every legal contract is to be carried into effect according to the intention of the parties thereto. In this case, the contract, on the part of the plaintiff was to furnish a quantity of mill-logs, cut and hauled x>n the banks of Kennebec river near the forks ; — on the part of the defendants, it was to pay three dollars for each and every thousand feet of merchantable boards, which said logs may be estimated to make. No mode is prescribed, in the written contract, by which this estimate is to be made; and it is understood that, from the nature of the article' to be delivered, the exact contents could not be ascertained until after the logs had been taken down *35the river and converted into boards. — But it- is alleged, on the part of the plaintiff, that this contract was entered into in reference to a usage or custom prevailing among log dealers on the Kennebec river, to ascertain the quantity of boards which may be made from a log or lot of logs by a scale called the Brunswick scale 5 — and it was submitted to the jury to determine, whether, at the time of making the contract, that scale was in such general and exclusive use, as that the parties in making their contract, must be presumed to have had reference to it, and would expect to ascertain the number of feet of boards, which the logs would make by that scale, and they have found in the affirmative.
This usage explains the intent of the parties, and not being in opposition to established principles of law, or in contradiction to the express terms of the written instrument, is deemed to form a part of the contract, as much as though actually incorporated into it, or expressly referred to. Williams v. Gilman, 3 Greenl. 267; 2 Stark. Ev. 453. Every instrument is presumed in its general terms to refer to the known and established usage respecting the subject to which it relates, and should be construed accordingly. 2 Ev. Both. 214. We are then to construe this contract as if it read “ The said Coopers, on their part, agree to pay the said Ileald three dollars for each and every thousand feet of merchantable boards that the above named logs may be estimated to make, such estimate to be made by the Brunswick scale.” Considering that the jury have found the usage, and that the parties contracted in reference to such usage, they are bound by it, and the plaintiff is entitled to three dollars per thousand according to that scale, unless the defendants entered into the contract under such circumstances as will absolve them from the whole or any part of it. They contend that the estimate by the Brunswick scale is erroneous ; — that its application to logs of the size of those delivered under this contract gives a larger quantity of boards than can be actually produced ; and that the plaintiff is, therefore, not entitled to the benefit of that part of the contract growing out of the usage, but must be holden to the strict quantity, or at farthest, to the estimate made by the Beamed scale, which is understood to be more exact in giving the quantity *36of boards to be produced from logs of tlie size of these, than the. Brunswick scale, in viewing this objection we must consider the situation of the parties at the time they made the contract, and the circumstances under which it was made. It was made between individuals residing on the Kennebec river, and engaged in the lum-. ber business. — It specified the situation from which the logs were to be taken, and where to be deposited, with such exactness as to leave no room for doubt but the defendants knew, or with reasonable diligence might have known, the description and general size of the logs for which they contracted. The Brunswick scale had been in use for many years, was printed and extensively circulated, and, being more convenient, bad come into very general use 5 and before and since the contract had entirely superseded the Learned scale.
The presumption is, from these facts, that the defendants knew the general size and quality of the logs..they purchased, and also the character of the scale by which they were to be estimated; and if they did not, that it was in consequence of a want of such diligence as the law presumes every man, having a due regard to his own inter-, est, would be likely to use.
It is said that the Brunswick scale is erroneous in favor of the vender, when applied to logs of a diameter insufficient to make five hundred feet, but that when applied to logs of a larger size,, it is em roneous in favor of the purchaser.
It is evident that a scale founded on general principles cannot, in its application, be equally exact in ail cases, If a given per cent. is to be deducted, as waste, from the contents of the log, it is apparent that if the deduction be correct in a large log, it cannot be so in a small one. But it is not found, and certainly it is not to be presumed, that the defendants, dealers in lumber as they are, could be ignorant of a fact so apparent and important to the interests of -all persons engaged in the lumber business. If they knew the character of the Brunswick scale, and they are to be presumed to have known it; if they knew, or with reasonable diligence might have known, the size and description of the logs they purchased, and of this there can be no doubt 5 and if they agreed that the amount of these logs should be estimated by the Brunswick scale, which the *37jury have found to be tbe fact, how can they escape from the fulfilment of their contract ? If the defendants’ engagement had been to pay three dollars for every thousand feet of merchantable boards that the logs would actually make, as the exact quantity could not be ascertained by cither scale, but only by actual admeasurement after the logs had been sawed, perhaps the evidence of custom establishing the Brunswick scale would have been irrelevant, as the extent of the defendants’ liability would depend upon the actual, not the estimated quantity. Such, however, is not the contract. The jury have settled the fact that the quantity was to be estimated by the application of the Brunswick scale. Whether that scale gave more or less, the parties are to be bound by their agreement.
But the defendants contend that the allowance made by the plaintiff to reader the contents of the logs equal to merchantable was insufficient. It appears that sixty feet on a thousand was allowed for this purpose, and the defendants contend that the additional allowance, which they claim as necessary to make the lumber equal to merchantable, would be more than tbe difference between the Brunswick and Learned scales, and that this constitutes a defence to the action. How stands the case relative to the allowance ? At the time that was made, the logs were open for examination, and were, examined by both parties ; and upon such examination, the defendants themselves proposed six per cent, as the proper allowance, winch was acceded to by the plaintiff and accordingly the allowance was made and accepted.
There is no pretence of any concealment of facts, or that the plaintiff had any greater or better means of ascertaining the quality of the logs than the defendant had. The parties stood on equal ground, and having settled that question themselves, it is not open for re-examination j certainly not in the absence of all suggestion of fraud or mistake. If there was any error in the estimate, it arose from defect of judgment, and as well might a party to any contract of exchange or purchase of property allege such a cause for anuuliug Ills contract as could the defendants in this case. But the mistake in estimating the quantity of lumber which the logs would make arose in a very different manner.
*38The case finds that the defendants used the Learned' scale in. making this estimate, when they should have used the Brunswick scale; — that the plaintiff complained of it, at the time, and repeated-; ly inquired of the defendants whether it was correct, to which they replied in the affirmative, and further stated that it was disputed up the river until it was compared with the Brunswick scale. The error arising from the application of the Learned, instead -of the Brunswick scale, in estimating the quantity of boards the logs would make, is, therefore, attributable wholly to the misrepresentation of the defendants, and if, in consequence thereof, the settlement made and receipt given were upon the payment of a sum less than was actually due upon an estimate according to the Brunswick scale, the defendants are bound in equity and in law to make up the deficiency, and this action will well lie to recover it.
We are of opinion that the ruling and instructions of the Judge were correct, and- that there must be Judgment on the verdict.