Opinion by
Mr. Justice Fell,The admission of the opinion of a witness to supplement his description is a subject that has been considered in a number of recent cases, in the last of which (Auberle v. McKeesport, 179 Pa. 321), it was said by our Brother Mitchell : “ The rule on this subject is that where mere descriptive language is inadequate to convey to the jury the precise facts or their bearing on the issue, the description by the witness must of necessity be allowed to be supplemented by his opinion, in order to put the jury in a position to make the final decision of the facts. But where the circumstances can be fully and adequately described to the jury, and are such that their bearing on the issue can be estimated by all men, without special knowledge or training, opinions of -witnesses, expert or other, are not admissible. The rule in this form was settled in Graham v. Penna. Co., 139 Pa. 149.”
The fact in issue which the testimony objected to tended to establish was the danger of cleaning the machine while the roller was in motion. This was not a danger which was obvious, or which came within the range of common experience. The description of the machine and its operation tended to establish the fact of clangor by establishing other facts from which it might be inferred, but the inference was to be based on special knowledge and experience in the use of such machines. As it was bjr no means clear that the descriptive language was adequate to convey to the jury the facts in relation to the operation of the machine or their bearing on the issue, there was ground for the evidence of opinion.
The statement in the charge that the plaintiff had given two *118weeks’ labor for the purpose of being properly instructed was not fully justified by the testimony, as the fact appears to be thát he was permitted to go about the mill with an employee for the purpose of being instructed. But we do not understand the instruction complained of to have been based on a supposed contractual relation, but on the general duty of an employer to instruct a boy in the use of dangerous machinery, and the fact that the defendants had recognized the necessity of instruction, and had undertaken to give it. The charge as a whole fairly presented the question at issue to the jury, and we find no error which calls for a reversal of the judgment.
The judgment is affirmed.