In order to maintain a petition under the Gen. Sts. e. 134, § 49, to compel the bringing of an action to try title to real estate, the petitioner must have substantially and practically the exclusive possession. It is not sufficient that he has a mere formal or nominal possession, which he can without disadvantage abandon and himself bring an action against the adverse claimant. Nor is it sufficient that he might be treated as a disseisor at the election of the latter; for any person asserting a title to land may be so treated at the election of. the rightful owner; and to give such a construction to the statute would be to enable any wrongful claimant to throw upon the rightful owner the burden of establishing his title. The petitioner must prove that he has the exclusive possession, as between himself and the respondent. If, as between them, the possession appears to be mixed or doubtful, the petitioner has not made out a case for compelling the respondent, rather than himself, to institute an action to try the title. Munroe v. Ward, 4 Allen, 150. Clouston v. Shearer, 99 Mass. 209. Tompkins v. Wyman, 116 Mass. 558.
*506The question whether the petitioner has proved such a possession, as to entitle him to an order that the respondent should bring an action, is to be decided in the first instance by the judge to whom it is presented. Upon questions of fact, or of the sufficiency of evidence, his decision is conclusive. It can be revised by the full court only for error in matter of law.
The facts proved in the present case warranted the inference that the contemporaneous leases from the petitioner and the respondent to the city of Boston were parts of one transaction, intended merely to transfer to the lessee, during the term mentioned in each lease, all the rights of the two lessors; and that neither lease was intended, or could be understood, as an assertion by either lessor, as against the other, of an exclusive right of possession of the demised premises. Petition dismissed.