Whether impossibility arising without the fault of the promisor, after a contract has been entered into, discharges the promisor from liability for failure to perforin, depends, in the first instance, upon whether his liability to perform is an implied obligation imposed by rules of law, or is created by an' express promise. If the surrounding facts and circumstances in connection with rules of law, impose the liability in question, a subsequent impossibility arising without the fault of the promisor, discharges him from liability.1 Thus, a common carrier, whose liability to transport and deliver is implied from the circumstances of his accepting goods for transportation, is discharged by subsequent impossibility, which amounts to an act of God,2 or an act of the public enemy. Thus an unexpected freezing of a river,3 or an unexpected flood,4 is an act of God. To effect a discharge of liability in such cases, the direct and sole cause of the loss must be the act of God.5 If the negligence of the carrier contributes to the loss, the fact that an act of God is in part the operating cause of the loss does not discharge his liability.6 Thus if a flood (such as the Johnstown flood) causes a wreck, and the carrier neglects to protect the goods, which are plundered, the negligence of the carrier to guard the goods contributes to the loss and the carrier is liable.7 Since these are cases in which the liability is imposed by law and not created by contract, further discussion here is unnecessary.

1Hiek v. Rodocanachi (1891), 2 Q. B. 626.

2Wald v. Ry., 162 I11. 545; 53 Am. St. Rep. 332; 35 L. R. A. 356; 44 N. E. 888.

3 Crosby v. Fitch. 12 Conn. 410; 31 Am. Dee. 745.

* Smith v. Ry.. 91 Ala. 455; 24 Am. St. Rep. 929; 11 L. R. A. 619; 8 So. 754: Ryan v. Rogers. 96 Cal.

349; 31 Pac. 244; Libby v. Ry.. 85 Me. 34; 20 L. R. A. 812; 26 Atl. 943.

5 Michigan Central Ry. v. Burrows, 33 Mich. 6; Davis v. Ry., 89 Mo. 340; Daniels v. Ballentine, 23 O. S. 532; 13 Am. Rep. 264.

6 Smith v. Trading Co.. 20 Wash. 580; 44 L. R. A. 557; 56 Pac. 372.