Now the boy had a tin of blanks at the right-hand side of the table. At its nearest point the plate or shield came to rest seven inches from the die, which means that from the edge of the shield the die was little more than a foot away. On the assumption that the pedal was detached, he was bringing down the shield with his left hand. There is nothing to my mind unnatural or improbable in supposing that he tended to move to the right corner of the table. Nor is it at all unlikely that, in attempting to gain speed at a new and not yet familiar task, he did not preserve proper and precisely regular sequence in the movements of his two hands. If he failed to do so and brought down the shield with his left hand before he had withdrawn his right hand, it might well be, if he was standing to the right, that his right hand would not be under the shield as it descended, but to the right of it, where there would be nothing above his forearm except the bar by which the shield was attached to the rod connected with the clutch. To say that this happened would be speculative, but to say that it might have happened shows that the shield did not form a secure fence or safeguard. A further consequence follows, however, from the conclusion that the imperative requirement of the statute that a dangerous part of the machinery should be securely fenced or guarded was not fulfilled. In Vyner v. Waldenberg Bros. Ltd.[6], an accident had occurred to an employee working at a circular saw, but how it really happened no one knew. It appeared, however, that the riving knife at the back of the saw did not conform with the statutory regulations for safety. Scott L.J., in delivering the judgment of himself, Mackinnon and Morton L.JJ., laid down the rule as follows: - "If there is a definite breach of a safety provision imposed on the occupier of a factory, and a workman is injured in a way which could result from the breach, the onus of proof shifts on to the employer to show that the breach was not the cause. We think that that principle lies at the very basis of statutory rules of absolute duty."[7]. It is not necessary to inquire whether their Lordships meant more than that the breach of duty coupled with an accident of the kind that might thereby be caused is enough to justify an inference, in the absence of any sufficient reason to the contrary, that in fact the accident did occur owing to the act or omission amounting to the breach of statutory duty. In the circumstances of this case that proposition is enough. For, in my opinion, the facts warrant no other inference inconsistent with liability on the part of the defendant. Napier C.J., having rejected the boy's account of the accident, said that he was left to conjecture how the accident happened. Having examined various theories, and being of opinion that the shield was a sufficient guard, he felt forced to the conclusion that, difficult as it was to accept the explanation advanced by the defence, it was less improbable than the other solutions he had considered. That explanation, as I understand it, was that the boy must have put his hand around and behind the guard whilst it was still down and the plunger or ram was striking at the rate of one hundred strokes a minute. This explanation appears to me to be a priori extremely improbable. It is not clear whether the hypothesis is that the boy did this owing to confusion or inadvertence or as a deliberate course of conduct. Positive proof of contributory negligence lies upon the defendant, and confusion and inadvertence would not justify a finding upon that issue against the boy (Piro v. W. Foster & Co. Ltd.[8]). It is not for the plaintiffs to prove that the accident took place otherwise than by some intentional act: Cf. per Greene M.R., Stimpson v. Standard Telephones & Cables Ltd.[9]. If, however, the meaning is that, owing to confusion or the like, and inadvertently, the plaintiff so acted, the question would again arise whether the shield was a sufficient safeguard or should have been more extensive. But, in any case, these do not appear to me to exhaust the possible explanations of the accident. There is one other that I would not be prepared to exclude, but it is one that implies liability on the part of the defendant. There was strong evidence that on other occasions the ram or plunger of the press in question had come down, notwithstanding that the treadle and guard had been up and had not been depressed (Transcript, Dunstan, pp. 107-108, 110; Coombs, 112-113; Jean Kraft, 116, 117, 118, 120; Walter Kraft, 122, 123, 124; Fry, 125-128, 130, 131, 132) and, although it was answered, it does not appear to me to have been answered very satisfactorily. Nor do I think that the attempt to exclude the mechanical hypotheses put forward to explain the happening of such a thing is completely convincing. The coming down of the ram in this fashion was called "repeating," and more than one hypothetical explanation was suggested. It is enough to mention one of them. It is the possible failure of the brake owing to its having been unscrewed to aid the movement by hand of the ram for inserting dies or else through lubrication. His Honour thought that for the machine to repeat, even so, would be impossible, but his conclusion could not but be affected by the mis-apprehension concerning the existence of a check or stop preventing the die falling when the clutch is not engaged. To suppose that the machine did repeat appears to me to be on the evidence a much more reasonable hypothesis than that the boy held down the guard and, notwithstanding the obstruction it afforded and the rapidly repeated strokes of the ram, either worked or experimented at the dies.