Chief Justice Agnew
delivered the opinion of the court,
*302As a whole, there was no error in the charge and answers to points. The instruction substantially was, that the defendant was liable for any insufficiency of the apron or flushing raised along the plaintiff’s wall to carry off the water sent down against it by the defendant’s roof. Having pitched his roof so as to carry the rainfall against and into the wall, it was his duty to raise the apron or flushing so high as effectually to protect the plaintiff’s store from being flooded by the water thus brought down. He had no right to carry the rain-fall on his premises into and upon the premises of the plaintiff. This was a wrongful act, which he could not justify by averring the openness of the 'wall of the plaintiff. But for the rain coming through the top of the wall, and not from the defendant’s roof, he was mot answerable. Any loss from that cause belonged to the. plaintiff. Nor was the defendant liable for the flow-age of an extraordinary rain, such as no experience or prudent forethought could have expected or guarded against, provided he had erected a sufficient apron or barrier against such as might be expected: Railroad Co. v. Gilliland, 6 P. F. Smith 445.
Coming to the question of contributory negligence, it is equally plain that the openness of the wall above the apron had nothing to do with the defendant’s illegal act in casting the flowage of his roof against and into the wall. The wall was there before, and when the defendant pitched his roof against it his duty required him to protect the plaintiff against an act wholly his own. If the apron or barrier were insufficient to prevent the flow of the water through the wall into the plaintiff’s store, the injury was one for which the defendant was alone responsible. It is true, the openness of the wall above an insufficient apron would increase the damage done to the goods in the store, but it did not cause the roof to be built or the pitch to be given to it, which threw the rainfall from the roof into the wall, and it did not, therefore, contribute to the act which produced the injury. But for the water falling through the wall above, and not brought down by the defendant’s roof, the plaintiff alone was answerable, for the defendant had no part in causing it to flow there. Each cause of injury was independent of the other. Hence the instruction was proper to allow no damages for the water running into the store through the wall above, provided the apron or flushing was sufficient. True, it is difficult to apportion the damages arising from the insufficiency of the apron; but this cannot exempt the defendant from a positive injury done by casting the flowage of his roof into his neighbor’s store. The rain-fall through the wall above a sufficient apron or barrier did not contribute to produce this injury, though it did add to the damage sustained by the plaintiff’s goods. Hence it was the duty of the jury to apportion the loss according to the actual injury of the defendant, by separating it, as well as they could upon the evidence,, from the loss arising from the openness of the wall above a sufficient apron. *303The evidence is a matter for the parties to consider and to produce. The contributory negligence which prevents recovery for an injury, is that which co-operates in causing the injury — some act or omission concurring with the act or omission of the other party to produce the injury (not the loss merely), and without which the injury would not have happened. A negligence which has no operation in causing the injury, but which merely adds to the damage resulting, is no bar to the action, though it will detract from the damages as a whole. Now, it is clear the open wall of the plaintiff bore no part in causing the defendant to build his roof and give it the pitch against the wall. The building of the roof and its pitch were the sole act of the defendant, and caused the injury to the extent of the flow of water from the roof. It was against this he was bound to protect the plaintiff. The difficulty of separating the damage from each independent cause may be great, but it does not change the nature of the tortious act of the defendant or relieve him from liability : Little Schuylkill Nav. Co. v. Richards’s Adm’r, 7 P. F. Smith 146-7; Seely v. Alden, 11 Id. 302. The qualifications complained of in the answers to the points were necessary to keep before the minds of the jurors the liability of the defendant for the insufficiency of the apron of barrier put up by him along the wall.
Upon the whole, we discover no error to correct.
Judgment affirmed.