468 HARVARD LAW REVIEW. issue ^ until it is first decided whether he has impliedly assumed the risk. In short, a master owes no duty to take care and is guilty of no negligence towards a servant who either actually or presumptively knows, or ought to know, the danger to which he will be exposed. Such a doctrine, however, is not peculiar to ser- vants. If the plaintiff knows the danger, then the defence is purely Volenti nonfit. If the danger is so obviously incident that he ought to know, and if he chooses to enter upon the work without ascertaining the extent of the risk,^ then the defence is the same absence of duty to warn against obvious dangers that exists in the case of any occupier of premises towards one entering upon them. Now, while a servant is held impliedly to contract to accept risks incident, the courts also hold that he does not thereby neces- sarily assume the risk of all unsafe and dangerous machinery.^ A master owes a duty towards his servant to supply reasonably safe machinery, so as not to expose hira to unnecessary risks,^ and a breach of this duty will give rise to an action against him, unless he has some defence in the special case. The defence usually set up is that treated by the courts as the second and third branches of the defence of Employee's Risk. In reality, however, it is not the defence of implied contract, but a more general one. When the danger or defect is not incident, but is contemporaneous with or subsequent to the servant's entry, the courts hold that in order that a plaintiff servant should be barred, (i) the servant must be capable of choosing, and of sufficient capacity to under- stand the risk.^ (2) He must know the danger.^ (3) He must not only know of the defect, but must appreciate the probability and ^ Joyce V. Worcester, 140 Mass. 248 (1885). 2 Cf. O'Maley v. Boston Gas Light Co., 158 Mass. p. 138 (1893). 8 Snow V. Housatonic R. K., 8 Allen, 445 (1864).
- Hutchinson v. York, N. & B. Ry, 5 Exch. 351 (1856); Bartonsheil Coal Co. v.
McGuire, 3 Macq. 307 (1856), H. of L. "The law justifies a servant in assuming that proper and sufficient appliances will be furnished him ; " . . . "an employee assumes the risk of such dangers as without the fault of the master naturally and ordinarily attend the employment." Buswell on Law of Personal Injuries, § 207 : Hough v. R. R., 100 U. S. 217 (1879); Northern Pacific R. R. v. Herbert, 116 U. S. 647 (1885). ° Coombs V. New Bedford, 102 Mass. 572 ; Pingree v. Leland, 135 Mass. 401 (1883) ; Richstain v. Washington Mills, 157 Mass. 541 (1892). ^ Russell V. Tileston, 140 Mass. 20 {1885) ; Gilbert v. Guild, 144 Mass. 604 (1887) ; Boyle V. N. Y. & N. E. R. R., 151 Mass. 103 (1890) ; Foley v. Pettee Machine Works, 151 Mass. 297 ; Rood v. Lawrence Mfg. Co., 155 Mass. 593 (1892) ; McCarthy v. Fos- ter, 156 Mass. 514 (1892); Downey v. Sawyer, 157 Mass. 420 (1892) : Patnode v. War- ren Mills, 157 Mass. 284, giving review of cases; Washington R. R. Co. v. McDade, ^ZZ U- S. 570 (1889).
