after making the foregoing statement, delivered the following opinion of the court:

The pivotal question in the case before us is this:

1. Had the dangerous condition of the instrumentality —the pork barrel—at the time of the injury to the plaintiff — (all set forth in the above statement of the facts)—existed for so long a time and under such circumstances that the defendant had constructive knowledge thereof a sufficient length of time prior to the accident for it to have removed such condition by the exercise of reasonable care?

The case involves an instrumentality in itself safe for the purpose for which it was provided by the master to be used and for which.it was used by the injured servant in the due course of the discharge ox the duties of his employment; but which was converted into an unsafe and dangerous instrumentality by the position in which it was placed for such use.

[1-6] The general rule is well settled, that the master is under an absolute obligation—is charged with a nonassignable duty—to use due care in providing and maintaining a reasonably safe environment for his servants while engaged in their work; and since, although the instrumentalities which are provided by the master are in themselves safe if properly placed and used, delinquencies *436of co-servants in the discharge of the duties entrusted to them may render the environment or place of work unsafe, it is, in such case, a continuing non-assignable duty of the master to exercise reasonable care, “* * by proper supervision and superintendence, to keep himself informed as to the manner in which the duties entrusted to them” (the-co-servants) “are performed.” N. & W. Ry. Co. v. Nuckols” Admr., 91 Va. 193, 207-8, 21 S. E. 342, 347, 2 Labatt on Master and Servant, sec 585. But it is also well settled, that there are limits to the master’s obligation of supervision and superintendence just stated. For instance, “he is not bound to supervise the merely executive details of the work to be done by his servants,” during the very progress of the work. 2 Labatt on Master and Servant, sec. 586. He is not bound to protect the servant from transitory-perils due to “no fault of plan or construction or lack of repair and to no permanent defect or want of safety in the. defendant’s works, or in the manner in which they had been ordinarily used.” Idem. sec. 587. Nor from dangers caused by the frequent changes in the progress of the work.. Idem. sec. 588. Nor from dangers due to the preparation oreare of the instrumentality, where such preparation and care of the instrumentality are a part of the work which the injured servant or his co-employee undertook to do.. Idem, sec 589. Nor “where the delinquent co-servant may have handled or placed a safe instrumentality so carelessly as to convert it, for the time being, into an injurious agency.. Idem. sec. 590 sub-sec. (a.) There is of course, as is also •well settled, a further limitation upon the non-assignable-duty of the master of supervision and superintendence, and-that is that such duty does not exist where the danger in question is known to the injured servant or is so open and obvious that he is presumed to have knowledge of it,, under the settled rules of law on that subject, and is taken to have assumed the risk of such danger. But when the-*437danger is not known or open and obvious, the other limitations above mentioned merely suspend the continuing duty of supervision and superintendence aforesaid resting upon the master during such time as such an abnormal condition may be reasonably anticipated by the injured servant to exist without the knowledge of the master. During such time the injured servant assumes the risk of the result of the negligence of his co-servants in the discharge of their executive duties in the premises. Idem. sec. 591. Such duty of the master, however, cannot be permanently abrogated or discontinued by his entrusting executive details of the work to his servants. He owes a duty to his servants, as aforesaid, to exercise reasonable care to keep himself informed how the executive duties entrusted to them have been performed by their co-servants. Hence, if such an abnormal condition, which causes the injury to a servant, is not merely temporary, but has continued for such a length of time that the master has actual or constructive knowledge of it and he has, nevertheless, allowed it to remain in that condition without taking reasonable steps for the protection of his servants from the danger attendant upon such condition, he is liable. And this is true also in other cases, independently of the cause of the abnormal condition, as when it is the result of an act of a stranger, or of a fellow-servant who is not a vice-principal, or of the operation of extraordinary physical force, or to some circumstance which is left wholly unexplained. 1 Labatt on Master and Servant, sec. 129; 2 Idem. sec. 568.

[7] The duty of inspection of such an instrumentality which is incumbent on the master, rests upon precisely the same principles and exists under the same circumstances as does the duty of supervision and superintendence, as aforesaid. 1 Idem. sec. 155.

[8] Now in the instant case the question of fact as to *438whether the danger in question was open and obvious was submitted to the jury under instruction No. 4 given at the request of the defendant (which is quoted in the statement preceding this opinion). There was ample evidence to sustain a finding of the jury that the danger was not open and obvious, so that that question was concluded in favor of the plaintiff'by the verdict of the jury.

[9] The question whether the dangerous condition of the barrel had existed for such a length of time that the master had constructive knowledge of it, was submitted to the jury under instruction No. 1 given at the request of the plaintiff (also quoted in the above statement). There was ample evidence to sustain an affirmative finding of the jury on that question. If the barrel was originally properly placed, and was subsequently misplaced by some co-servant of the plaintiff by a negligent discharge of executive duties touching the details of the work—the possibility of which is suggested in the testimony of Mr. Whit-ten for the defendant—still, according to Whitten’s own testimony it was his duty “to put it báck.” It was a question for the jury whether if he had gone about the discharging of that duty in a reasonable time he would have ascertained the dangerous position of the barrel—and also whether if the assistant superintendent had discharged his reasonable duty in the premises he would have ascertained the position of the barrel. Hence that question of fact also was concluded in favor of the plaintiff by the verdict of the jury.

(According to the evidence in the case it was a concessum that the defendant allowed the dangerous condition to remain without taking any steps for the protection of Its servants therefrom.)

[10] It is true that said instruction No. 1 also predicated the liability of the defendant upon the alternate fact, if the jury should so find, that the barrel in question was *439originally placed in the unsafe position aforesaid. Accurately speaking this would not have rendered the defendant liable in damages in the premises if this had been but a temporary peril due to the negligence of some co-servant in the discharge of executive duties in the progress of the work, which peril did not remain in existence long enough to affect the defendant with constructive knowledge thereof; but no objection is made before us to the instruction on this ground by the assignments of. error, and doubtless none such was made in the court below, where the trial seems to have been had upon the view, concededly regarded as correct, that if the barrel was misplaced when it was originally stored, the defendant was affected with constructive knowledge of its dangerous condition for such a length of time before the accident that it was liable. Doubtless the point under consideration was of no practical value in view of the testimony in the case and hence was not raised in the trial court. At any rate it is not raised and the question is not presented before us for decision whether there was error in such feature of such instruction.

2. We come now to the consideration of the action of the trial court in refusing to give instructions Nos. 5 and 6 asked for by the defendant.

These instructions could properly be given in a case in which the non-assignable duty of the master with respect to providing reasonably safe and suitable instrumentalities or a reasonably safe place for the work of its servants is suspended, because of the danger being open and obvious, or because of the existence of other limitations upon that duty, such as are above mentioned, where the peril is transitory and due to causes such as are above referred to. In such cases the master owes no duty to the injured servant with respect to dangers which are open and obvious, or which are discoverable only by inspection. He, in such cases, is not chargeable with any duty of immediate inspec*440tion .or with any constructive knowledge of the condition of the immediate environment of the servant; whereas the servant, is charged with the duty of being watchful for the dangers likely to arise as a result of the ever changing conditions. Va. Coal & Coke Co. v. Asbury’s Adm'r, 117 Va. 683, 86 S. E. 148.

[11] But where the dangerous condition of the environment, to whatever cause it may be due, is not open and obvious, but has existed for so long a time that the master’s non-assignable duty in the premises aforesaid is no longer suspended, but exists, then the situation of the master and servant respectively, touching the duty of discovery of the dangerous condition is very different. There is then a present duty on the part of the master to exercise due care by inspection, supervision and superintendence to inform himself, as above set forth, and he is affected with constructive knowledge of all the information which the exercise of such care would bring to him. Whereas, the injured servant, in such case, has no duty resting upon him of affirmative action to discover latent dangers; he may rely upon the assumption that the master has exercised reasonable care in that direction for him; for, as to the servant, in such case, “* * the test is, not the exercise of care to discover dangers, but whether the defect is known or plainly discemable by the employee,” in the exercise of reasonable care to avoid open and obvious dangers. Choctaw, etc., R. v. McDade, 191 U. S. 68, 24 Sup. Ct. 24, 48 L. Ed. 96. To the same effect, Robinson v. Dininny, 96 Va. 41, 30 S. E. 442; Richlands Iron Co. v. Elkins, 90 Va. 249, 17 S. E. 890. Almost innumerable other authorities so holding might be cited. Hence we see that the giving of the instruction under consideration in such a case would be improper. They would, indeed, nullify the existence of 'the non-assignable duty of the master aforesaid in the premises.

*441It is urged by the defendant that the McDade and Elkins cases just cited, respectively, involve defective appliances and defective construction. The principle involved, however, is the same as in a case of an unsafe place to work due to a dangerous condition, which is not open and obvious, for which the master is responsible.

The following cases are cited for defendant and urged upon our consideration as sustaining the position that said instructions Nos. 5 and 6 should have been given by the trial court, namely: Honaker Lumber Co., Inc., v. Call, 119 Va. 374, 89 S. E. 506; Russell Creek Coal Co. v. Wells, 96 Va. 416, 31 S. E. 614; Va. Iron Coal & Coke Co. v. Asbury’s Adm’r, 117 Va. 683, 86 S. E. 148; Lynchburg Foundry Co. v. Dalton, 121 Va. 480, 93 S. E. 587; Darracott v. C. & O. Ry. Co., 83 Va. 288, 294, 2 S. E. 511, 5 Am. St. Rep. 266. But these were all eases, either of open or obvious danger, or of transitory perils attendant upon the executive details of the work to be done by the servants, with an absence of any element of permanency of the dangerous condition sufficient to impute constructive knowledge thereof to the master.

[12] 3. A number of cases from other States are cited for defendant upon its position that the danger incident to the tipping over of the barrel was a risk which was assumed by the plaintiff and one Virginia authority not above referred to, is included among them.

The Virginia case cited is that of Wilson v. So. Ry. Co., 108 Va. 822, 62 S. E. 972, where the servant was injured, while assisting in unloading 85-pound rails from a railroad car, in consequence of the turning of one of the rails under his foot from some unexplained cause, while the work was being done in the usual manner. Here the danger was a transitory peril and arose from the mere executive details of the work being done by the co-servants and it was, besides, as was held, the result of an accident for which no one could be held responsible.

*442In Manley v. Minneapolis Paint Co., 76 Minn. 169, 78 N. W. 1050, cited, the plaintiff was injured in assisting in unloading a barrel of ocher from a railroad car by rolling it down a skid 2 feet wide and 18 inches long, extending on an incline of 10 inches, to a platform 4 feet above the ground. The plaintiff stood on the skid in front of the barrel with his hand on the top and sides of it to ease it down. It came faster than he expected and he stepped aside, but too far and fell off an unguarded side of the platform and was injured by the fall. The peril arose in the mere executive details of the work, and besides it was open and obvious. See Richmond Locomotive Works v. Ford, 94 Va. 627, 27 S. E. 509.

In the case of Mathis v. Kansas City, etc., Co., 185 Mo. 484, S. W. 66, cited, the plaintiff was himself charged with the duty of placing the plank in position to stand upon in doing his work. That was a part of the work the plaintiff undertook to do.

The same principle is involved in the ladder case of Borden v. Daisy Roller Mill Co., 98 Wis. 407, 74 N. W. 91, 67 Am. St. Rep. 816, cited. And as to the alleged defect in the ladder, it consisted in the lack of spikes to prevent its slipping on the floor, which was held to have been an open and obvious danger.

In Langley v. Wheelock, 181 Mass. 474, 63 N. E. 944, the plaintiff was injured by the falling of one of a number of metal bars of different lengths which stood on end on the floor and rested against the wall of the store, being held in place by pins in planks about four feet up from the floor on the side of the wall. There was nothing to obstruct the view of these pins four feet up from the floor, or of the position of the bars as the plaintiff occasionally worked in a few feet of them and passed to and fro about his work. The court held that the danger was open and obvious, and besides that there was no evidence in the case to show *443what caused the bar to fall which injured the plaintiff; although there was an hypothesis that it might have fallen because of the fact that two bars were placed against one of the pins and the thickness of the bars was such that the bar which fell and injured the plaintiff laying on top of another bar projected beyond the end of the pin and, hence, was insecure and from that cause slid and toppled over.

In Bradley v. Forbes Tea & Coffee Co., 213 Mo. 320, 111 S. W. 919, cited, the plaintiff knew the tendency of the piles of sacks of coffee to settle and bulge out and hence was held to have assumed the risk of the sacks falling.

In Hofnauer v. White Co., 186 Mass. 47, 70 N. E. 1038. the plaintiff, a salesman in defendant’s store, was injured by the falling of a medicine chest from a shelf above her. There was no evidence in the case disclosing from what cause the chest fell, except- that the shelf was not level. But other chests upon the shelf were not affected by the inclination of it. The court, it is true, said that “for aught that appears its fall may have been attributable to carelessness of an employee in not replacing it securely after it had been taken down and shown to customers.” However, there was nothing to obstruct the view¡ of plaintiff of such a position of the chest on the shelf, and she was held to have assumed the risk of the danger, on the ground that it was open and obvious.

In the trap-door cases of Clough v. Hoffman, 132 Pa. 626, 19 Atl. 299, 19 Am. St. Rep. 620, and The Theresina (D. C.) 31 Fed. 90, cited, the cause of the displacement of the cover of the openings in question did not appear and the displacement was but temporary, in each case, not continuing for a sufficient length of time to affect the defendant with constructive knowledge of the dangerous condition. In the case of Kupp v. Rummell, 199 Pa. 90, 48 Atl. 679, cited, the trap-door was opened immediately before the accident by a co-servant after notice to and as*444sent of plaintiff. The latter, therefore, knew of the dangerous condition and it was not a continuing one for a time sufficient to impute constructive knowledge of it to the defendant.

None of such authorities, therefore, have any controlling bearing on the case at bar.

But one other position of the defendant remains for om consideration, and that is this—

[13] 4. That the plaintiff might have ascertained from the foreman Whitten, Who was in charge of the goods on the floor on which the glycerine was stored, where it was, instead of himself searching for it, as he did-and the rule is invoked that where two methods are open for the performance of a duty, one dangerous and the other safe for the operator, one who chooses the dangerous rather than the safe method is precluded from recovery.

We do not think that the rule invoked is applicable to the instant case.

It is true that Whitten testifies that he knew where the glycerine was stored and could have given the plaintiff that information, if called upon to do so. But he was not out on the floor of the room but back in the cooling room at the time and did not see the plaintiff, nor did the plaintiff see him, when the plaintiff came upon the floor in search for the glycerine. Besides, there is no evidence in the case that it was the duty of the plaintiff to make such inquiry of the foreman, or that such was the custom at any time. On the contrary the plaintiff testified expressly that in searching for the glycerine himself, as he did, he acted in accordance with the custom which had been followed in that regard during the whole period that he had been in the employment of the. defendant prior to the accident (three years and nine months).

For the foregoing reasons we find no error in the action of the trial court or in the judgment under review, and the cause will be affirmed.

Affirmed.