Opinion by
Henderson, J.,The plaintiff charged the defendant with negligence in three respects: failure to provide its stone cars with appliances to keep them in place during the.process of loading; in omitting to instruct the plaintiff, an inexperienced employee, of danger not obvious in the exercise of ordinary care, and in failing to provide the plaintiff with a safe place in which to work; and *268evidence was offered tending to support each of these allegations. The defendant was engaged in the manufacture of cement and this included the operating of a quarry out of which quantities of rock were elevated by a derrick hoist and dumped onto small cars in use to transport the rock to the mill. The cars were backed by hand into the derrick and the rock lifted from the quarry was conveyed to an elevation about two feet above the car and dumped at an angle of about forty-five degrees into the car. The momentum of this load of stone forced the car forward and the plaintiff was caught between it and one of the derrick posts thereby receiving a serious injury. He had been in the service of the company about ten years and at the time of the accident and for a long time before served in the capacity of water boy, carrying water to the quarries. lie had never before worked at this derrick and as claimed by him was not familiar with the operations there carried on. On the day of the accident he was removing from the track where the cars were loaded a lot of loose stone which had fallen from the cars in the process of loading. He had been engaged at this work for about fifteen minutes when he was hurt. The derrick hoist stood on the brink of the quarry where there was a sheer descent of about thirty-six feet to the bottom. The plaintiff’s evidence was to the effect that when the car was backed into the loading place he was standing on the ledge outside of the derrick where there was a space of two or three feet next to the quarry; that he was about to step across the track to get away from the car because of the risk he ran of being hit by stones from the derrick bucket and had gone about four feet toward the other side of the track when the foreman who was present directed him to pick up a large stone which had fallen from the car and throw it over into the quarry, at the same time assuring him that there was plenty of time. The plaintiff obeyed this instruction and immediately thereafter started to cross the track when the bucket of stone was dumped into the car, forcing the car against him and injuring him. Evidence was offered to show that the method of loading the car, with reference to its stability, was not the same as that used in other *269quarries and that it was more dangerous. The defense was that the defendant was not negligent in providing suitable appliances; that the method adopted was a usual and ordinary one in the business; that the plaintiff was not acting under the direction of the foreman in clearing the stone away from the track and that he was guilty of contributory negligence.. The assignments of error relate to the subject of contributory negligence, the competency of the evidence of experts on the manner of loading and some portions of the charge of the court. Giving credit to the plaintiff’s evidence, there is little basis for the contention that the plaintiff was chargeable with contributory negligence. It is true that six or seven cars had been brought to the derrick and taken away while he was employed about it that morning, but there is no evidence that he observed the effect of the discharge of the stone into the car or that he had reason to apprehend the danger which overtook him. Moreover, if he worked under the express order of the foreman and remained on the ledge to throw over the stone with the assurance that there was plenty of time for him to get away he had a" right to rely on the advice of his superior unless the danger was apparent. The servant is not required to act on his own judgment against that of his employer, and if the latter give him positive instructions to go on with a particular task he may recover for any injury received if the work was not imminently dangerous: Reese v. Clark, 198 Pa. 312; Maines v. Harbison-Walker Co., 213 Pa. 145; Levy v. Rosenblatt, 21 Pa. Superior Ct. 543. The plaintiff, then, not only had this assurance of sufficient time to get away but he was also as he supposed in danger of being struck by stone discharged from the bucket and knocked into the quarry below if he remained where he was. If in the emergency the choice of means of protection which he made proved to be least safe he is not to be charged with negligence on that account. It may be taken for granted'that in accepting the service imposed upon him he assumed such risks as were incident to its performance from causes which were so obvious that he had an opportunity to ascertain them, but as to special danger of the employment of which he had no knowledge and which was *270not apparent he was entitled to notice and his employer became liable if he failed to advise him of the risk. It is due to him that the dangers of the situation be pointed out and that he be instructed in the things he should know in order that he may provide for his own safety: Rummel v. Dilworth, Porter & Co., 131 Pa. 509; Lillie v. American Car & Foundry Co., 209 Pa. 161; DeGrazia v. Piccardo, 15 Pa. Superior Ct. 107. Many other authorities are to the same effect. The learned trial judge left to the jury the question whether the forward movement of the car was an obvious one which the plaintiff knew or should have known, and also the question whether the plaintiff was specialty instructed to throw the stone into the quarry and whether he was told that there was plenty of time to do that and to get away and the instructions on these points were clear and full and in strict accordance with the authorities cited and many others. The action of the court on the admission of the expert evidence showing the manner in which cars were loaded at other quarries and cement works accorded with the ruling in Bardsley v. Gill, 218 Pa. 56, and Cunningham v. Bridge Works, 197 Pa. 625. The plaintiff’s allegation was that the defendant failed to adopt the usual safeguards to secure the stability of the car when loaded. The witnesses called had had large experience in the manufacture of cement and a considerable observation of the methods adopted at cement quarries in that region. It would have been competent to prove the method adopted in the particular quarries at which the witnesses worked. As was said in Bardsley v. Gill, 218 Pa. 56: “No single instance is sufficient to prove a custom, but custom is certainty made up of an aggregation of different instances. It was a question of fact for the jury to say what the general custom was after the evidence of the methods in use in various concerns was before them.” The evidence certainty tended to show the usage at similar establishments, and its value was to be estimated by the jury after the witnesses had shown familiarity with the subject. It is not enough to prove that the method adopted at the defendant’s quarry was not the samé as generally used. If the evidence stopped there the inference might be that it was a newer *271and better method. The plaintiff must go further and show that it was not as well adapted to securing the safety of the operatives as the plan in use elsewhere. The charge of the court adequately and clearly covered the, questions of law involved and guarded the rights of the defendant to the extent to which it was entitled under the evidence. We do not find any sufficient reason to justify the reversal of the judgment.
The judgment is affirmed.