Hill, C. J.
(After stating the foregoing facts.)
1. The main question arises on the grant of a nonsuit. Does-the evidence for the plaintiff, most favorably considered, show any evidential facts, or inference reasonably deducible from evidential facts, tending in any appreciable degree to establish his right to recover? If so, there is “proof to support the plaintiff’s allegations,” and a nonsuit is erroneous. Corcoran v. Merchants and Miners Transportation Co., 1 Ga. App. 743 (57 S. E. 962) ; Vickers v. Atlanta & W. P. R. Co., 64 Ga. 307. It is an elementary principle of law that the duty of inspection is one of the absolute duties of the master. The law commands the master to inspect, and to continue to inspect, dangerous machinery, in order that he may discover any defects in construction, or such as are likely to be caused by wear and tear of operation, and, when discovered, to promptly remedy them, ,for give timely warning of the. consequent danger to his servant. The duty of inspection is affirmative, and must be continuously fulfilled and positively performed. Southern States Cement Co. v. Helms, 2 Ga. App. 308 (58 S. E. 524); Buzzell v. Laconia M. Co., 48 Me. 113 (77 Am. Dec. 212). “It is the duty of a proprietor of a mill to inspect . . the machinery and appliances under his control, . . to anticipate and provide for the wear and tear of belts and pulleys, to test them at regular intervals and to ascertain whether they are running-true or not, . . and, in the ease of pulleys, fast or loose, to observe whether they are in good order and fit to be relied upon to perform their work properly and without unnecessary danger *321to servants.” Petrarca v. Quidnick Mfg. Co., 27 R. I. 265 (61 Atl. 648).
In the light of these legal propositions, let us briefly consider the facts of this case. The plaintiff testified, that after he had stopped the machine in the usual and customary way, by shifting the belt from the tight to the loose pulley, and that when he was in the act of doing his work on the carding machine, the machine suddenly started; that neither himself nor any coservant did anything to start the machine; that if the machine had been in good condition, it would not have started, without some human agency, with the belt on the loose pulley ; and that, with a machine in good condition, the belt, when placed on the loose pulley, would stay there until replaced on the tight pulley; that the machine was started by the automatic creeping of the belt from the loose pulley on to the tight pulley, and that this automatic creeping of the belt was due to a certain defective condition of the machinery; and that he had no knowledge of such defective-condition, and was not charged with the duty of finding it out. Could the defective condition of the machinery described by the plaintiff, and which he says caused his injury, have been discerned by reasonable inspection? If so, the law imposing the duty of inspection upon the master charges him with knowledge of such defective condition. Southern Cotton-Oil Co. v. Gladman, 1 Ga. App. 262 (58 S. E. 249). In connection with the evidence of the plaintiff on this vital issue of negligence relating to the defective condition of the machinery, an admission of the defendant corporation in its answer is not entirely without probative value. The defendant admitted that “said machine - would run on the loose pulley indefinitely, unless some unforeseen agency or condition should cause it to change.” The “unforeseen agency” in the present case, according to the evidence of the plaintiff (which was admitted to be the truth, on the motion to nonsuit), was not the agency of himself or of a fellow servant. The only agency, therefore, that could have caused the change' was the condition of the machinery itself. But the master is under a legal duty to foresee any and every defective condition of his machinery that can be ascertained by ordinary diligence, and to provide against any injury to his servant from such defective condition. He can not escape liability by saying the thing complained of happened, or was caused by “some *322unforeseen agency or condition.” The full measure of his duty is not reached by the statement that the trouble which caused an injury was “unforeseen.” It must have been “unforeseeable” by the exercise of all due diligence on his part to discover and to avoid hurtful consequences.
The doctrine of res ipsa loquitur is invoked as applicable to the facts of this case, and the learned attorney for the plaintiff in error presents a very able and interesting argument in favor of his contention. We do not think it necessary to enter into a discussion of this doctrine. The maxim has been a prolific inspiration to much useless and wasted juridic erudition. Practically, as we said in the Monahan case, 4 Ga. App. 680 (62 S. E. 127), the doctrine is simply a rule of circumstantial evidence, which permits .an inference to be drawn from proved facts. It furnishes a working basis for reasonable hypothetical conjecture, and gives scope for legitimate reasoning by the jury. The philosophy of the doctrine is stated in section 5157 of the Civil Code. “In arriving at a verdict, the jury, from facts proven, and sometimes from the absence of counter-evidence, may infer the existence of other facts reasonably and logically consequent on those proved.” Under the guidance of the law as comprehensively stated in this section of the code, we think a prima facie case of negligence in respect to the matters alleged was made out by the plaintiff, and that the ultimate question was one of fact for the jury. In a case identical on the facts with the one now under consideration, the Supreme Court of Khode Island, in a well considered and clearly reasoned decision, deduces conclusions of law so sound and so apt that we are led to quote tliem with approval. “In an action for injuries to a servant, caused by his arms being drawn into a carding machine which he was cleaning, the burden of proof imposed upon the plaintiff to show that the injury was caused by defendant’s negligence, while he himself was in the exercise of due care, was sustained by evidence that the machine started automatically without fault on the servant’s part.” “The automatic creeping of a driving belt on a carding machine from one pulley to another, so as to start the machine, affords sufficient evidence that the machine is out of order, and that the master has been negligent in failing to inspect the same, to authorize a recovery in favor of a servant *323injured by the starting of the machine without fault on his part.” Petrarca v. Quidnick Mfg. Co., supra.
2. Another ground of negligence relied upon by plaintiff is that there was no guard on the belt to prevent it from creeping; and it is insisted that if there had been a belt guard, it would have prevented the defective condition of the belts and pulleys from causing the accident. The absence of a belt guard was not disputed. Whether the master, in the exercise of due care, should have had one on the belt to prevent injury to his servant was purely a question of fact. And it is .equally clear that whether it was contributory negligence of the servant to work, with knowledge that there was no belt guard, was a question for the jury. To determine these questions, others would have to be considered. Was it usual and customary to have belt guards on similar machinery? Did the absence of a belt guard indicate that the machine was in •a good or a defective condition? Would a belt guard have prevented the injury? None of these issues could be determined as matter of law. “Whether an employee is guilty of contributory negligence because he remains in the service of his employer after he has knowledge of defects in the machinery with which he is required to work is a question for the jury,” Farley v. Charleston Basket Co., 50 S. C. 222 (28 S. E. 193). Knowledge of defects, ■on the part of the servant, is not conclusive of negligence. It must depend upon the facts of the particular case. Labatt on Master and Servant, §§322, 323, 439; Roach v. Haile Gold Mining Co., 71 S. C. 79 (50 S. E. 543). In the Earley case, supra, it was distinctly held not to be contribiitory negligence as matter of law for the servant to operate a machine xipon which there was no guard. The question was for the jury.
3. It is insisted by the defendant that the plaintiff not only had equal opportunity with the defendant of knowing of the defects, if they existed, but he was the very person through whom the defendant performed the duties required of it under the law, of inspecting its machinery and keeping it in proper shape. If these facts are affirmatively shown by the testimony, then the plaintiff would have no right to recover damages, even if there was ■evidence of negligence on the part of the defendant. On this point the plaintiff testified that he did not know of the defective condition of the belt or pulleys, and had no opportunity of dis*324covering their condition, as his sole duty pertained to the card-grinding. Whether the plaintiff had the same opportunity as the defendant, of knowing of the defects alleged and proved, would depend upon the character of such defects, — whether they were latent or patent. Where the defect is superficially discernible of plainly apparent to the eye, the servant has the same opportunity of seeing it and knowing of it as the master. But if the defect is latent, the master would be held bound to discover the fact sooner than the servant, because the duty of inspection rests on the master, and not on the servant. In a case of latent defects,— those which are only discoverable by proper inspection, — the master is necessarily held to a higher standard of conduct than the servant, since the master owes to the servant the duty of inspection. Hubbard, v. Macon Ry. & Light Co., ante, 223 (62 S. E. 1018) ; Cedartown Cotton Co. v. Miles, 2 Ga. App. 83 (58 S. E. 289); Union Pac. Ry. Co. v. Jarvi, 3 C. C. A. 433 (53 Fed. 65). In the strong and terse language of the attorney for the plaintiff in error, “the master’s duty of knowing the danger is antecedent, and the servant’s subsequent. The master must anticipate danger and prevent it before it arises; the servant need only observe and avoid it after it has come. The master is the sentinel, the servant only a guard. The master says to the servant, ‘You are to work, I will watch.’ The servant replies, ‘My eyes are intent upon your work; when danger draws nigh, warn me that I may escape.’” Therefore, if the plaintiff in error was- under no duty to inspect the belts and pulleys, he can not be held impliedly to have known of their defective condition and to have assumed the risk. It is true the plaintiff testified that it was his duty to repair any part of the machinery when he found it out of repair-, or when it was reported to him as being out of repair, if he was able to do so. But the duty of repair, under these circumstances, does not embrace the duty of inspection. Green v. Babcock Lumber Co., 130 Ga. 469 (60 S. E. 1042); Hubbard v. Macon Ry. & Light Co., supra. The plaintiff, according to his testimony, was only called upon to repair apparent defects and those which were reported to him. It would still be the defendant’s duty to warn him of any hidden or latent dangers in some parts of the machinery separate from those which he was called upon to repair. We do not think, therefore, that it can be held in this ease, as matter of law, under the *325evidence, that the plaintiff assumed the danger arising from defective belts or pulleys, if such defects were found by the jury to have been latent. Martineau v. Nat. Blank Book Co., 166 Mass. 4 (43 N. E. 515).
4. The testimony set out in the two special assignments of error, and which was excluded by the court, we think should have been admitted. A portion of this testimony, it seems to us, falls clearly within the classification of expert testimony. One of the main questions in the case was as to the cause of the sudden and unexpected starting of the machine after the belt had been taken off the tight pulley and put onto the loose pulley. Plaintiff testified that the sudden movement of the machine was. not caused by himself or any coservant. What would cause machinery of this character to start automatically? Certainly one not familiar with machinery of like kind could have no reliable opinion on the subject. It was a question to be elucidated by the testimony of one familiar with the movement of machinery of a similar character under similar conditions. Eor this reason, we think the testimony was clearly admissible. Civil Code, §5287; 1 Wig. Ev. §451, on page 542, and eases in the notes. The objection to a consideration of these exceptions, on the ground that it does not appear that it was made known to the court below what would have been the answers to the questions propounded, we think is only well taken as applicable to a small portion of the testimony offered; as to a large portion of the testimony offered the exceptions are sufficiently specific. We, therefore, hold that the court erred in excluding the testimony as set out in these two exceptions, and also- erred in granting the nonsuit! Judgment reversed.