This case comes before us on exceptions to the rulings and instructions to the jury by the presiding judge of the court of common pleas ; and the first question to be decided is, whether that court had jurisdiction of the cause. By St. 1840, c. 87, § 1, the supreme judicial court has original and exclusive jurisdiction of “ all actions respecting easements on real estate, *238but not including complaints for flowing land.” So that the question is, whether this is an action respecting an easement on real estate. The foundation of the action, as alleged in the writ, is the erection, by the defendant, of a dam in and across Charles River, below the mill and close of the plaintiff, whereby the water of said river had been prevented from flowing and passing off from the plaintiff’s water wheel, along said river, in the usual course, and as of right it ought to have flowed and passed off, and thereby causing back water on the plaintiff’s wheel.

At the trial, the defendant admitted the erection and continuance of the dam, and claimed a right thus to obstruct the watercourse, and to cause the water to flow back on the plaintiff’s land and water wheel; and the principal question at the trial was, as to the validity of the claim. But this claim of an easement over the plaintiff’s land does not affect the question of jurisdiction ; for the defendant might or might not set up such claim, and thus would have the power to oust the court of its jurisdiction, whether the action should be brought in this court or in the court of common pleas. The question, therefore, whether this court hath exclusive jurisdiction of an action respecting an easement on real estate, must depend on the declaration in the writ, by which it must appear that such an easement is claimed, and that its validity is necessarily involved in the decision of the case. And that, we think, does appear by the declaration in the present case. The right claimed by the plaintiff is that of having the waters of Charles River flow over the land of another, below his land and mill, and at the place where the obstruction was erected, in its accustomed course, and free from all artificial obstruction ; and this we consider as a claim of right to a natural easement. The right which a party has to the use of water flowing over his own land is undoubtedly identified with the realty, and is a real or corporeal hereditament, and not an easement; but the right of a party to have the water of a stream or watercourse flow to or from his lands or mill, over the land of another, is an incorporeal hereditament, and an easement, or a predial service, as defined by the civil law. And it is immaterial whether the watercourse be natural *239or artificial; or whether the right is derived ex jure natures, or Dy grant or prescription. It seems, however, that the right to receive a flow of water, and transmit it over the land of another, although a natural easement, not beginning by grant or the assent of parties, may be claimed by prescription. Gale & Whatley on Easements, (Amer. ed.) 88. Woolrych’s Law of Waters & Sewers, 118. Saunders v. Newman, 1 Barn. & Ald. 258. Hazard v. Robinson, 3 Mason, 277. 3 Kent Com. (3d ed.) 441. Wright v. Williams, 1 Mees. & Welsb. 77. Such a natural easement is not extinguished by unity of possession of the dominant and servient tenements. Shury v. Piggot, 3 Bulst. 339. S. C. Poph. 166. W. Jon. 145. Latch, 153. Noy, 84. It is not material, however, to the decision of the question of jurisdiction, to determine whether the plaintiff’s claim is well founded or not. He certainly claims an easement over the land where the obstruction was erected, and the court of common pleas are not authorized to take cognizance of such a claim. The right claimed is as clearly the claim of an easement, as would be the claim to transmit the water from the plaintiff’s mill through an artificial watercourse or canal over the servient tenement.

We are of opinion, therefore, that the court of common pleas had no jurisdiction of this case, and that it must be dismissed.

After this opinion was announced, the defendant’s counsel moved for costs. Wilkinson, for the plaintiff, resisted the motion, and cited Williams v. Blunt, 2 Mass. 207. Clark v. Rockwell, 15 Mass. 221. Osgood v. Thurston, 23 Pick. 110. Bank of Cumberland v. Willis, 3 Sumner, 472, 474. 1 U. S. Digest, Costs, 53.

The plaintiff’s counsel object to the allowance of costs, and rely on the rule laid down in Osgood v. Thurston, 23 Pick. 110. The rule is there said to be, “ that where the writ is bad on the face of it, and it is manifest that the court ha? no jurisdiction, so that the proceedings may be quashed or. motion, no costs are allowed.” However correct this rule may be, as applicable to a case where the want of jurisdiction is so manifest that the cour would quash it ex officio, without plea oz *240appearance, we are of opinion that it cannot be applied, without manifest injustice, to the present case, which depends, as to the question of jurisdiction, on the construction of a recent statute, which, in the opinion of the court of common pleas, sustained the jurisdiction of that court. And this construction, we understand, was given to the statute, on the objection of the defendant to the jurisdiction of that court. Judgment was rendered against the defendant, from which he could not be relieved, but by removing the case into this court, on exceptions, or by writ of error. Under these circumstances, we think it cannot be maintained, that the defendant is not entitled to costs, as the prevailing party. The rule, on which the plaintiff’s counsel rely, is not of universal application to all cases where the court has not jurisdiction. It must be a clear case, where no judgment would be rendered, although the defendant should not appear. In Thomas v. White, 12 Mass. 370, costs were allowed, though the court had no jurisdiction ; on the ground that the want of jurisdiction was not manifest on the face of the writ, but was ascertained by' the defendant’s plea, in which, on oyer, the condition of the bond declared on was set out. So in suits in equity, costs are generally allowed where hills are dismissed on demurrer for want of equity jurisdiction. It is therefore by no means universally true, that costs are not to be taxed for the defendant, where the suit fails for want of jurisdiction of the court over the subject matter of the suit.

In all cases where the want of jurisdiction does not manifestly £.nd clearly appear on the face of the writ, and the question of jurisdiction, as in this case, is a fair subject of discussion, and for the decision of the court, there seems to be no reason why the defendant, if he prevails by the decision of the question in his favor, should not be entitled to costs. And for these reasons, we are of opinion that judgment for costs must be entered, in this case, for the defendant.*