1. There can be no doubt that the defendants were liable in this action on the facts which must have been found by the jury in rendering a verdict for the plaintiff under the instructions given to them by the court. It is now the well settled rule of law in this commonwealth that in all cases wher a highway, turnpike, bridge, town way or other way is laid across a natural stream of water, it is the duty of those who use such franchise or privilege to make provision by open bridges, culverts or other means for the free current of the water, so that it shall not be obstructed and pent up to flow back on lands belonging to the riparian proprietors. And it is their duty not only to *358make such bridge, culvert or passage for water, but to keep it in such condition that it shall not obstruct the stream; Rowe v. Granite Bridge, 21 Pick. 344. Anthony v. Adams, 1 Met. 284. Lawrence v. Fairhaven, 5 Gray, 116. Perry v. Worcester, 6 Gray, 544.
2. Evidence tending to show an adjustment of damages with the plaintiff, and a satisfaction thereof in whole or in part, was rightly excluded. No such ground of defence was set forth in the answer, and as it was clearly matter in discharge of the action, it was necessary to plead it in order to render proof of it admissible. St. 1852, c. 312, § 18.
3. The case was submitted to the jury under instructions which embodied so much of the defendants’ prayers as was consistent with the rules of law. The damage caused to the plaintiff’s property was found by the jury to have been occasioned solely by the negligence of the defendants, to which no improper or careless act or omission of the plaintiff in any degree contributed.
4. The loss of rents, suffered by the plaintiff, cannot be recovered in this action. This was in the nature of special damages, not necessarily resulting from the careless or negligent act of the defendants, which should have been specially set forth in the declaration, in order that the defendants might have notice of this claim and be prepared to meet it. Baldwin v. Western Railroad, 4 Gray, 333. But as this item of damages was assessed separately by the jury, the plaintiff can remit so much of the amount of the whole verdict as is equivalent to the sum of the rents thus found to have been lost, and thereupon the entry will be Judgment on the verdict.