after stating the case, delivered the opinion of the court.

As the libellants deemed the agreement to “ take the northern passage ” of sufficient importance to have a printed form changed, so that it might be incorporated in express words into the charter party, and this “ for the benefit of the cargo,” which Avas perishable, it is eAddent that the Avords used had some meaning Avhich indicated clearly to the minds of the contracting parties the direction the vessel Avas to take on her way from Gibraltar to Boston. It is also evident, from the fact that the vessel Avas bound to take the northern passage, that the parties understood there was more than one passage which A7essels Avere in the habit of taking in making that voyage, according as their bills of lading or their charter parties , required, or the circumstances made desirable. It implies that there Avere one or more other passages AvLick those engaged in the trade kneAV by other names or other *473 descriptions. "What “ the northern passage ” as used in this contract means, therefore, is either a question of fact or a question of construction applicable to understood facts. .

If it is, as the court below says it appears to be, a term of art, which, taken by itself, without the aid of the testimony, is unintelligible, then its meaning in “ the art ” — the trade — is one of the material ¿facts in the case on which the rights of the parties depend, and it should have been found and put into the findings of fact which the Circuit Court was required by law to make. The statement of the court, now in the record, implies that there is in fact some particular passage between Gibraltar and Boston, which those engaged in that trade know as “ the northern passage.” If there is, then that is the passage the vessel was bound to take, and it was error in the court to decide that its determination, according to the preponderance of the evidence, was immaterial, for the choice of passages was matter of obligation, not of convenience merely.

If in point of fact there is no passage to which the name or description of “the northern” has been given in the trade, then the question becomes one of construction as applied to the known facts of the business. The inquiry is, not as to which passage would be the quickest, or even the best, or which another contract would require of another vessel, but which is “ the northern passage ” Avithin the meaning of this contract. The evident purpose of the libellants Avas, to keep the vessel as far as possible in the coolest of the passages that those engaged in the trade Avere accustomed to take, because it is found as a fact in the case that a cool temperature is necessary to the preservation of the cargo,' and that the coolest Avater is north of the Gulf Stream, oAving to the fact that there is a cold current betAveen it and the American coast moving in an opposite direction.

Under these circumstances, if the testimonj^ failed to sIloav that any particular passage had acquired in the trade the name of “ the northern,” it A\ras error to rule that the vessel might voluntarily take any other of the knoAvn or accustomed passages than one which would carry it in a northerly di *474 rection through the coolest waters and into the coolest temperature. That this was the expectation of the parties is shown by the fact that the stipulation as to the passage was made “for the benefit of the cargo,” the preservation of which required that it should be kept “ in as cold a temperature as possible, short of the freezing point.” The court should have ascertained from the evidence what passages there were between Gibraltar and Boston which vessels were accustomed to take, and then determined which of them this vessel was allowed by its contract to choose as “the northern.”

The decree is reversed, and the ccmse remanded for fwther proceedings in conformity with this opinion.