In order to show negligence on the part of the defendant, the plaintiff relies on the omission to give him suitable *190instructions in reference to the dangers to which he would he exposed in the course of his employment. His injury arose from coming in contact with the revolving cog wheels of a machine; and the instructions which he was entitled to receive must therefore have been concerning the danger from that cause. But it seems to us that it must fairly be assumed that the plaintiff had all such knowledge as it was the duty of the defendant to impart to him. There was no peculiar or secret source of danger. Anybody seeing the machine in motion must soon become aware of the danger which would arise from coming in contact with it. The duty of the defendant would be sufficiently discharged by pointing out to the plaintiff the situation of the machine, and the rapid revolution of the wheels when in operation, and explaining the probable effect of touching them under these circumstances. Certainly the duty of the defendant did not extend so far as to require the giving of a special caution on every occasion when he might be called upon to pass near the machine. The master is only bound to give such instructions as are reasonably necessary in order to enable the servant to understand the perils to which he is exposed by reason of his employment. A servant is held to take the risk of such dangers as are known and understood.
In the present case, the duty of the defendant to the plaintiff would not require an explanation of anything which he already sufficiently understood. In order to show actionable negligence on the defendant’s part, it was incumbent on the plaintiff to show an omission to inform him of something which he needed to know in order to be safe. Sullivan v. India Manufacturing Co. 113 Mass. 396. In the absence of anything to show the contrary, the plaintiff must be assumed to have had the intelligence and understanding which are usual with boys of his age. There is nothing to show that he did not know the danger of coming in contact with the revolving wheels of the machine. It must be assumed that he was well aware of it. The accident happened in consequence of his omitting to guard against a known peril. He had been employed in the same room for a period of nearly two months. There is no reason to suppose that explicit instructions, if given to him at the beginning of his employment, in reference to the danger of touching these wheels when in motion, would *191have added anything to what he must fairly be presumed to have known at the time of the accident.
It would be carrying the doctrine of holding employers to the duty of giving reasonable instructions to their servants quite too far, to require a special caution every time a boy is sent on an errand, under circumstances like those disclosed in the present case. The injury appears to have arisen from a lack of sufficient precaution on his part, and not from the negligence of the defendant. Russell v. Tillotson, 140 Mass. 201. Williams v. Churchill, 137 Mass. 243. Wheeler v. Wason Manufacturing Co. 135 Mass. 294.
In Coombs v. New Bedford Cordage Co. 102 Mass. 572, 598, which is chiefly relied on by the plaintiff, the plaintiff had been at work for the defendant only one day, and under these circumstances the evidence of the nature of the work, and of the position in which he was to do it, were considered to warrant the jury in finding that the plaintiff was manifestly incapable of understanding and appreciating the dangers to which he was exposed by the gearings, or manifestly incapable of performing the work there with safety.
In the present case, we are of the opinion that there was no sufficient evidence of negligence on the part of the defendant.
Exceptions sustained.