VOLENTI NON FIT INJURIA. 467 compensation. A mere duty to look out for one's self or another cannot and should not always be turned into a contract to do so.^ There are really three distinct branches of the defence of Em- ployee's Risk which have never been clearly separated by the courts, and the three lines of cases have been treated as if they all came under the principle of implied contract: (i) Cases where the plaintiff is injured by a machine or condition purely incident to the work when he enters upon it; (2) cases where the danger or defect is not incident but actually known by the plaintiff at the time of entry; (3) cases where the machine or condition becomes dangerous or defective subsequent to his entry, but where he con- tinues to work with knowledge. The first line of cases is the only one to which strictly Judge Shaw's doctrine is applicable. The other two lines come under a far more general doctrine and should never have been decided under a rule peculiar to the relation of master and servant. As to the first branch, in order that an employer may maintain the defence of implied assumption of the risk, it is laid down by the courts that (i) the risk must be incident to the employment.^ (2) It is not enough that the peril be incident, unless it so ob-r viously incident that the plaintiff knows it, or from its character and circumstances will be presumed or ought to know it.^ (3) Plain- tiff must not only know but also appreciate the extent of the risk and danger; (4) the question of the plaintiff's negligence is not at 1 Riley v. Baxendale, 6 H. & N. 445 (1861). Wilde, J. : "It does not follow that wherever a duty is cast upon a person, the law will imply a contract on his part to perform it." 2 Structure near R. R. track one of the dangers of the business, Lovejoy v. V>. & L. R. R., 125 Mass. 82 (1878); Fisk v. Fitchburg R. R., 158 Mass. 239 (1893). Broken cars, Yeaton v. B. & L. R. R., 135 Mass. 418 (1883). Location of tracks and switches. Wood V. Locke, 147 Mass. 605 (1888) ; Coombs v. Fitchburg R. R., 156 Mass. 200.(1892); Tuttle V. Milwaukee R. R., 122 U. S. 194 (1886). Slipperiness of floor, Murphy v. American Rubber Co., 159 Mass. 267 (1893) ! Wilson z/. Tremont Mills, 159 Mass. 155; Kleinest v. Kunhardt, 160 Mass. 231 (1893). Darkness of passage-way. Murphy v. Greely, 146 Mass. 200 (r888). Dangers on shipboard, Williams z/. Churchill, 137 Mass. 294 (1884) ; Anderson v. Clark, 155 Mass. 370 (1892). 3 Goldthwaite v. Haverhill R'y Co., 160 Mass. 555 (1893) ■ Connors v. Morton, id. 335; Scanlon v. B. & A. R. R., 147 Mass. 487 (1888) : "The risk of safety of machinery is not assumed by the employee unless he knows of the danger, or unless it is so obvious that he will be presumed to know it," Myers v. Hudson Iron Co., 150 Mass. p. 134 (i88g) : "or which by exercise of ordinary care he ought to know to be incident to the nature of the business in the place where and the manner in which it is carried on." Wheeler & Wilson Mfg. Co., 135 Mass. 293 (1883). Cf. O'Maley v. Boston Gas Co , 158 Mass. 138, and Ladd v. New Bedford R. R., 113 Mass. 413 {1876). VOL. VIII. — 8 62
