Bingham, J.

1. A servant does not assume the risk of dangers that are unknown to him and of which he would not have learned by the exercise of ordinary care. Henderson v. Williams, 66 N. H. 405.

Notwithstanding the plaintiff admitted that he knew other men besides those associated with him in repairing the carrier were at work making repairs in the mill on the day of the accident, his evidence tended to prove that he did not know any of them were at work in the digester room, or that their work was of a nature calling for the use of signals which might be mistaken for his. Hence it cannot be said as a matter of law that the plaintiff assumed the risk of injury from such a cause. It was for the jury to say whether he knew, or in the exercise of ordinary care should have known and appreciated the danger, and assumed the risk of injury therefrom. Slack v. Carter. 72 N. H. 267; Kasjeta v. Company, ante, p. 22.

*151 2. A master is bound to provide sucb reasonable rules and regulations for the conduct of his business, and to give such instructions, as will enable his servants to do their work in safety. If ordinary care in the conduct of his business requires that he should provide such rules and regulations and give such instructions, then his duty arises. McLaine v. Company, 71 N. H. 294, 297.

That the work in which the plaintiff was engaged at the time he received his injuries was dangerous and of such a nature as to require reasonable rules and instructions for the guidance of the plaintiff and his associates in the performance of their duties, cannot be doubted. The defendants did not contest this question at the trial. Their contention there was that adequate instructions were gi ven the men and, had they been followed, that the accident would not have happened. The plaintiff, on the other hand, contended and introduced evidence tending to prove that no instructions were given; that the men in the course of their work made use of two methods of signaling for the carrier to start and to stop —one by calling out “ go ahead ” or “ all right,” the other by raising the hand; that the former was used by the plaintiff in signaling to the middleman, and the latter by him in signaling to the man at the clutch; that in this way the work proceeded with reasonable safety until the defendants, without the knowledge of the plaintiff and his associates, introduced a new element of danger by sending other men into the digester room to do work which required the use of signals, and who, in ignorance of the plaintiff’s dangerous situation, gave a signal that was mistaken for a signal from the plaintiff. From this evidence the jury could find that the defendants were negligent in not informing the plaintiff of this new and unknown danger and in failing to make some reasonable provision for the conduct of the work in view of this added peril.

If the evidence warranted a finding that the middleman was negligent in not first ascertaining whether the plaintiff was out of the carrier before giving the signal to start, so that the defendants’ negligence was not the sole cause of the accident, nevertheless the jury would be warranted in finding that their negligence was a cooperating cause, for which they would be responsible, the plaintiff being in the exercise of due care. “ The master is liable for an injury to his servant caused by negligence of the master cooperating with negligence of a fellow-servant, the injured servant being in no fault.” Matthews v. Clough, 70 N. H. 600.

Exceptions overruled.

All concurred.