held that the tug did not become an insurer by the contract of towing, but was simply bound to perform its contract with ordinary skill and diligence, and as the captain and mate of the tug, and the mate, who was in command of the schooner, thought the berth above Polk street bridge safe from the approaching fire, therefore the contract of towage was executed. No action would, therefore, lie on the alleged promise to return, as that was a promise without consideration, and also was on the condition that the tug should not be otherwise employed. The evidence also showed that when it became apparent that the Fontanelle was in danger, the tug.used every reasonable effort to rescue her; consequently the tug was not liable. In support of his views, Judge Blodgett cited [The Webb] 14 Wall. [81 U. S.] 414, in which the court says: “It must be conceded that an engagement to tow does not impose an obligation to insure or the liability of common carriers. The burden is always upon him who alleges the breach of such a contract to show either that there has been no attempt at performance, or that there has been negligence or unskillfulness to his injury in the performance. * * * The contract requires no more than that he who undertakes to tow shall carry out his undertaking with that degree of caution and skill which prudent navigators usually employ in similar services.” Also, Caton v. Rumney, 13 Wend. 387; Pennsylvania D. & M. S. Nav. Co. v. Dandridge, 8 Gill. & J. 240; Wells v. Steam Nav. Co., 2 Comst. [N. Y.] 204, where it is held that “whenever steamboats are employed in towing they are bound to no more than ordinary care and skill in management; they are not quo ad hoc common carriers, and the law of common carriers is not applicable to them.” The libel was then dismissed at the cost of the libelant.