¶1The ground of the plaintiff’s right of action was that he was injured in performing dangerous work that he was put to do by the defendants. The machine was dangerous only because there was danger in working upon it; and, if it was in fact dangerous, it was immaterial that the danger might have been averted by appliances protecting against it. The defendants are not liable to the plaintiff because they used a dangerous machine, but because they employed the plaintiff to use it in.ignorance of the danger. If the plaintiff undertook the work knowing the danger, the defendants are not liable, although they might have prevented the danger by guarding against it; if the plaintiff did not know of the danger, proof that the defendants could not have guarded against it would be no defence. The verdict shows that the question whether the defendants were negligent in not having a guard upon the machine was not in the case. If it was founded upon the fact that the machine was not dangerous, or on the fact that the plaintiff had knowledge of the danger, it was equally immaterial that the defendants had not provided a guard. Want of due care by the plaintiff, or knowledge of the danger by him, which the jury must have found if they found the machine to be dangerous, would have prevented a recovery, equally whether the defendants could or could not have guarded against the danger. See Ladd v. New Bedford Railroad, 119 Mass. 412, and cases cited ; Pingree v. Leyland, 135 Mass. 398; Coombs v. New Bedford Cordage Co. *605102 Mass. 572; Sullivan v. India Manuf. Co. 113 Mass. 396; Taylor v. Carew Manuf. Co. 140 Mass. 150; Rock v. Indian Orchard Mills, 142 Mass. 522; Linch v. Sagamore Manuf. Co. 143 Mass. 206.
¶2The exceptions are to the exclusion of questions put to an expert. Three of the questions related to the use of a guard, an immaterial matter, and were properly excluded. The defendants were liable on account of the actual danger, and not from the fact that they might have prevented it.
¶3The only other question, the exclusion of which was excepted to, related to the material matter of the knowledge by the plaintiff of the danger. The danger was from revolving knife blades. The machine was used to cut the nap from woollen cloth. By the action of the machine, the cloth was drawn between various rollers and then under the revolving blades, and the plaintiff’s duty was to guide the cloth in passing through the machine, and to smooth out wrinkles and folds in it with his hands. The danger of using the hands near unguarded revolving blades was apparent. The plaintiff contends that he was exposed to a peculiar and hidden danger, from the effect of the tractile power of the cloth in drawing a hand resting upon it under the knives. The witness testified as an expert, in regard to this, that it would not be safe to put the hand upon the cloth in a certain position near the knives when the cloth was moving at a certain rate. He was then asked whether the danger of the operative’s hand being drawn under the knives, if placed upon the cloth, would be obvious to an inexperienced operative; and the question was excluded. In learning what the danger was, the jury may have been aided by the opinion of those who had special knowledge in regard to it; but, having found that, the question whether it was obvious to the common mind, or required a special education and experience to see and appreciate it, was addressed to the common knowledge of the jury, and not to the special knowledge of an expert. We think the questions were all properly excluded. jExceptions overruled.