Opinion by
Mr. Justice O’Brien,This action of trespass was brought by appellant, Barber, to recover damages for injuries sustained by plaintiff in an accident on September 16, 1964. Defendant-appellee’s preliminary objections were sustained and judgment entered in favor of defendant. The case is before us on appeal.
Plaintiff’s complaint alleges that on September 16, 1964, while working upon a scaffold approximately three feet above ground level, he fell from the scaffold into an open hole which was in excess of sixteen feet in depth. Plaintiff alleges that defendant was negligent in failing to cover the hole so as to prevent persons, such as plaintiff, from falling into it. It is stipulated that plaintiff was caused to fall when, while removing a metal brace from the scaffold, the brace slipped suddenly, and plaintiff fell backward from the scaffold.
Defendant demurred by way of preliminary objection. The preliminary objection was sustained by the *221court below on the ground that even if defendant’s act of leaving the sixteen foot deep hole uncovered was negligent, that negligence was not the proximate cause of the plaintiff’s injury.
The court below was entirely correct in sustaining the preliminary objection. Assuming arguendo, as appellant contends, that appellant was a business visitor to whom appellee owed a duty, and assuming also that appellee violated its duty and was negligent, there can still be no recovery. For appellant’s injury resulted not from appellee’s negligence, but from the slipping of the brace. Two cases of this court are particularly in point. In Frisch v. Texas Co., 363 Pa. 619, 70 A. 2d 290 (1950), plaintiff slipped on a public sidewalk and fell into a grease pit on the property of defendants. Plaintiff contended that defendants were negligent in failing to cover the grease pit. This court, after stating that the sole issue in the case was whether the uncovered grease pit was the proximate cause of plaintiff’s injury, held that it was not: “The grease pit was in no way the cause of plaintiff’s injury and recovery cannot be predicated upon the mere conjecture that his injuries might have been less serious had the grease pit not been there.” The other case particularly in point is Zlates v. Nasim, 340 Pa. 157, 16 A. 2d 381 (1940). In that case, plaintiff fell on a porch by virtue of her own negligence, but because defendant had negligently left the entrance to the cellar unguarded, plaintiff fell all the way to the cellar. We said there, at p. 159: “While [plaintiff] may have sustained greater injuries by falling down the cellar steps than she would have received had she dropped to the cement floor of the porch, that makes no difference in searching out the cause of her fall. With that the unguarded stair opening had nothing to do.” Similarly, in the instant case, while appellant may have sustained greater injuries by falling to the bottom of the hole than *222he would have received had the hole been covered, that has no bearing on the cause of the fall. Whether the fall was caused by appellant’s own negligence, as in the cases cited, or by a third party’s negligence with regard to the scaffold cannot and need not be determined here. The same result obtains either way, for it is clear that appellee was not the cause of the fall.
Nor is appellant’s contention apt that appellee’s negligence was the proximate cause of his injuries because without appellee’s negligence, appellant would have fallen merely three feet rather than nineteen feet. The two cases described above, Frisch v. Texas Co., supra, and Zlates v. Nasim, supra, both indicate that the extent of the injuries is irrelevant to a determination of the cause of the accident. Moreover, a long line of eases in this court has held that the determination of the extent, if any, of incremental injury resulting from defendant’s negligence is impossible to determine. This court has continually stated that, in a case like the instant one, a lessening of injury, absent defendant’s negligence, is pure conjecture. Frisch v. Texas Co., supra; Zlates v. Nasim, supra; Quinn v. Philadelphia, 224 Pa. 176, 73 A. 318 (1909); Elliott v. Allegheny L. Co., 204 Pa. 568, 54 A. 278 (1903).
Appellee’s alleged negligence was not the proximate cause of appellant’s injuries. The judgment of the court below is therefore affirmed.