As the supposed interest of the juror depends

solely upon facts, the decision of that question belongs exclusively to the judge, on the trial, if the challenge be then made; but if not then known, and a motion for a new trial be made on that ground in the court of common pleas, the same rule must apply, and the decision of the judge is conclusive. Rev. Sts. c. 95, § 27; Borden v. Borden, 5 Mass. 79, 80. The same rule applies when the competency of a witness depends on questions of fact. The decision of the judge is conclusive, unless he prefers to reserve the question. Dole v. Thurlow, 12 Met. 159.

The court are also inclined to the opinion, that any motion for a new trial in the court of common pleas is an application to the discretion of that court, and that then- decision is conclusive; but we do not place our decision of this case on that ground, the other being decisive. Gray v. Bridge, 11 Pick. 189. Exceptions overruled.