226 HARVARD LAW REVIEW. undertakings as those of telegraph companies 1 and passenger carriers, 2 which concern intangible rights, have been enforced apart from contract. It is to be noticed at the outset that there are two classes of undertakers: private undertakers, who assume a duty /re hac vice, and public or " common " undertakers, 3 whose business it is to as- sume the duty. It might be said that the latter undertake a duty to all the world at the time they enter into their public calling; and that a breach of such a duty as that sounds rather in tort than in undertaking, if I may use the phrase. But this seeming duty to all the world is of limited application. Generally, it re- quires a special relationship to give rise to a right of action. A railroad company is under no different obligation as to the world at large from that of the private owner of a carriage who invites his friend to ride. There is only one exception to this statement ; that of the public duty of an innkeeper, common carrier, and anciently a common farrier, to receive every applicant that can be served. But this duty differs entirely from the duty toward the customer after the relation between them is actually undertaken. It depends upon the so-called " custom of England," is grounded on public policy, and a breach of it does indeed sound only in tort. 4 If we except this duty, and the anomalous liability of a common carrier " as an insurer," the obligations of both public and private undertakers are governed by the same rules. II. From a practical point of view, the theory here advanced is an important aid in the exceedingly difficult and delicate matter of ascertaining the degree of care required of one who undertakes a duty. This matter has caused much difficulty. On the one hand, the mooted distinction between gross and ordinary negligence in cases of bailment is involved ; on the other, the question, What i N. Y. & W. P. Tel. Co. v. Dryburg, 35 Pa. 298; contra, Playford v. U. K. Tel. Co., L. R. 4 Q. B. 706. 2 Foulkes v. Met. Dist. Ry., 5 C. P. Div. 157 ; contra, Alton v. Midland Ry., 19 C. B. N. s. 213. 3 The word " common," now restricted to carriers, was formerly applied to all who exercised a public profession : common innkeeper, 11 H. IV. 45 ; common surgeon or farrier, 19 H. VI. 49; common hoyman, 2 Ld. Raym. 909, 918; common hackney-coach- man, 2 Show. 127. 4 Jackson v. Rogers, 2 Show. 327 ; Heirn v. McCaughan, 32 Miss. 17.
