after making the foregoing statement of the case, delivered the opinion of the court.

It is settled law in the federal courts that the master owes the duty of using proper diligence in the employment of competent men to perform the duties for which they are engaged, and that he cannot escape this responsibility by delegating his duty to an agent who is a fellow servant of the injured employé; and after the employment of the servant it is the duty of the master to keep himself advised as to his fitness, so that an incompetent person may not continue in the service to endanger the lives and limbs of his fellow servants. Railroad Co. v. Henthorne, 19 C. C. A. 623, 73 Fed. 634, and the large number of cases cited in that opinion by Judge Taft. The evidence in this case, however, does' not show that the negligence of this jackman caused the injury. The plaintiff testified that he had given no signal before the wire was pulled by the jackman. But it appears that the jackman should receive the signal from the lineman nearest to him, who occupied the pole between the plaintiff and the jackman. There is no evidence showing that the-lineman next to the jackman had not transmitted the signal, although the evidence is clear that he had not received the signal from the plaintiff. It is possible that the jackman did not receive this signal, but it was necessary to show that he did nqt before the-plaintiff could recover. If he did receive the signal, it was his duty to tighten the wire, as he did, and the defendant could not be charged' with negligence. It is not sufficient to show that an accident has occurred, and that it may have been caused by the negligence of an incompetent servant, for whose employment and retention in his service the master is liable, but the fact must be shown. In this case the court would not have been justified in allowing the jury to infer the absence of a signal when it could have been shown by positive proof if the signal had not been given. In Patton v. Railway Co., 179 U. S. 658-663, 21 Sup. Ct. 275, 277, 45 L. Ed. 361, the court says:

“The fact of accident carries with it no presumption of negligence on the-part of the employer, and it is .an affirmative fact for the injured employé to establish that the employer has been guilty of negligence. Railway Co. v. Barrett, 166 U. S. 617, 17 Sup. Ct. 707, 41 L. Ed. 1136. * * * It is not sufficient for the employé to show that the employer may have been guilty of negligence, — the evidence must point to the fact that he was. And where the testimony leaves the matter uncertain, and shows that any one of half a dozen things may have brought about the injury, for some of which the employer is responsible, and for some of which he is not, it is not for the-jury to guess between these half a, dozen causes, and find that the negligence of the employer was .the real cause, when there is no satisfactory foundation in the testimony for that conclusion. If the employé is unable to adduce sufficient evidence to show negligence on the part of the employer, it is -only one of the; many cases in whjch the plaintiff fails in his testimony, and no mere sympathy for the unfortunate victim of an accident justifies any departure from settled rules of proof resting upon all plaintiffs.”' •

. In the absence .of proof, pf the tightening of this wire before receiving the proper signal, which was a necessary fact, the court would not have been justified in submitting the case to the jury, and it is *911not necessary to notice the other questions discussed by counsel at the hearing.

The judgment is affirmed,