Mr. Justice Mercur

delivered the opinion of the court,

This was a suit to recover back certain commissions, claimed by, and allowed to, the plaintiffs in error on a previous settlement between the parties. It was a settlement of the business enterprise, generally, in which the parties were jointly interested; and also of the particular transaction in which the plaintiff in error claimed to have paid the commissions. On that settlement the defendant in error was found to be indebted in a sum exceeding $20,000. At this time the defendant paid a portion of the sum in which it was found to be indebted, and gave drafts for the residue, payable in a few months thereafter. More than two years after the settlement, and after the payment of the drafts, this suit was brought. On the trial the objection does not appear to have been taken that the settlement could be overthrown only on proof of fraud, mistake or ignorance of legal rights in making it; but the merits of the claim, made by the plaintiffs in error for the commissions, were inquired into, as if no settlement thereof had previously been made. The actual payment of the commissions by the plaintiffs in error was not strongly questioned; but whether they had been paid in good faith, or in a heedless and improvident manner, was the contention. They had been paid to Shoemaker & McIntyre, who were coal brokers. The plaintiffs in error sought to prove a faithful and careful performance of their agency. In furtherance of this object it was clearly evidence of good faith and prudence for them to show that they had sold according “to the usual and customary method of the Philadelphia coal trade,” and that such method was to sell “ through the agency of brokers, to whom a commission was paid.” It was here the office of the parties was kept and their business transacted. It is urged that the offer is insufficient, inasmuch as it does not propose to prove a usage based upon a custom “which was established, uniform and general.” It is true the offer is not in these precise words, yet we think the language imports substantially the same meaning. “ Usual and customary ” clearly import something more than casual or exceptional cases. They indicate such a fixed and established usage as to be declared general by the trade. Besides, it is not necessary to prove all the elements of a custom necessary to make a law; the object here is to interpret a contract. The usages of a particular trade or business are presumed to be known to those engaged *291therein. These may, therefore, in the absence of any. express stipulation inconsistent therewith, be supposed to have entered into the understanding of the parties in making the contract. They furnish a most valuable aid in arriving at the mutual assent of the parties, and when not contrary to law are admissible in evidence: Lewis v. Marshall, 7 M. & G. 744; United States v. Duval, 1 Gilpin 372; 2 Greenl. Evid., § 251; Finness v. Howe, 8 Wend. 247; Outwater v. Nelson, 20 Barb. 29; Girard Fire and Marine Insurance Co. v. Stephenson, 1 Wright 293; Helme v. The Philadelphia Life Insurance Co., 11 P. F. Smith 107 ; McMasters v. The Pennsylvania Railroad Co., 19 Id. 374. The evidence shows the Reading Railroad Company purchased the largest quantity of the coal. Such a purchaser may well have been considered very desirable. If so, it was certainly pertinent to show that those sales could only be made through Shoemaker & McIntyre. We think, therefore, the evidence covered by the third and fifth assignments should have been received. The seventh assignment is to that portion of the charge of the court wherein it is said, “ the defendants held a large majority of the stock of the company, therefore, the control of the company was entirely in their hands.” It is true Carter & Co. did hold a majority of the stock, but they had accepted it under an arrangement by which they were to have a minority of the directors. The board consisted of five directors. Carter & Co. were to have, and in fact did have, only two of them. All the coal in question was sold within one-year. No change'of directors was made within that time. The controlling management was therefore in the other three directors. Under the circumstances, and for the time in question, a majority of the stock did not put “ the control of the company entirely in the hands of Carter & Co.,” and, in so charging, the learned judge erred.

Inasmuch as the reason given for the removal of the secretary was not made known to the plaintiffs in error, they ought not to be affected thereby. It therefore follows that the evidence covered by the first assignment ought not to have been received.

Judgment reversed and a venire facias de novo awarded.