In truth, there were two sets of duties,--one not peculiar to bailees, arising from the assumpsit or public calling of the defendant, as just explained; the other, the ancient obligation, peculiar to them as such, of which Southcote's Case was an example. But any obligation of a bailee might be conceived of as part of a contract of bailment, after assumpsit had become appropriated to contract, the doctrine of consideration had been developed, (both of which had happened in Lord Coke's time,) it seemed unnecessary to distinguish nicely between the two sets of duties just mentioned, provided a consideration and special promise could be alleged. Furthermore, as formerly the defendant's public calling had the same effect as an assumpsit for the purpose of charging him in tort, it seems now to have been thought an equally good substitute for a special promise, in order to charge him in assumpsit. In Rogers v. Head, /1/ the argument was, that to charge one in assumpsit you must show either his public calling at the time of the delivery, or a special promise on sufficient consideration. This argument assumes that a bailee who received goods in the course of a public employment, [186] for instance as a common carrier, could be charged in this form of action for a breach of either of the above sets of duties, by alleging either his public calling or his reward and a special promise. It seems to have been admitted, as was repeatedly decided before and since that case, that one who was not a common carrier could have been charged for non-delivery in a special action; that is, in case as distinguished from assumpsit.