638 FEDERAL BUPOBTSB. �oome in coaflict li/ith the righta of creditors and subsequent purchasers. �The continuance of the estate conveyed to the grantees, in the grant before us, was dependent upon the performance of the condition subsequent expressed in the grant. By the termsof the condition it was to be performed by the grantees "at their own oonvenience and time." As the grantors de- rived no immediate benefit in consideration of the grant, and were to receive profits only upon the performance of the con- dition, it was the duty of the grantees to perform the condi- tion subsequent in a reasonable time. What a reason- able time is the law does not accurately define, but leaves that question to be decided by the judge according to the facts and circumstances of a case, as admitted by the pleadings or as ascertained by the finding of a jury. As the evident intention and motives of the grantors, in eiecuting the grant without any present consideration, were that they might receive continuons profits from the working of the min- erais and metals in the lands, the obligation of the grantees was continuons; and if they failed to open the mines, or dis- continued to work them when opened, and did not resume operations in a reasonable time, their estate, under the grant, would be forfeited by this breach or non-performance of the condition subsequent contained in the grant. �The doctrines of estates upon condition seem to have been originally derived from the feudal law. A tenant was under obligation to render continuons service, and if he neglected to perform his service the lord could, by a wrii of cessaidt, obtain possession of the fief, as such continuons service was the consideration for the grant of the estate. �. It was insisted, on the part of the plaintiffs,^ that at the common law the breach of a condition subsequent did not absolutely determine the estate ; that a freehold could only be defeated by an entry or claim made on the part of the grantor or his heirs, and until that was done the estate lost none of its original qualities and incidents, and that this right of entry or claim could not be assigned to a sti^anger to the conveyance. It was also insisted in the argument that, ��� �
