“Any seaman who shall suffer personal injury in the course of his employment may, at his election, maintain an action for damages at law, with the right of trial by jury, and in such action all statutes of the United States modifying or extending the common-law right or remedy in cases of personal injury to railway employees shall apply; and in case of the death of any seaman as a result of any such personal injury the personal representative of such seaman may maintain an action for damages at law with the right of trial by jury, and in such action all statutes of the United States conferring or regulating the right of action for death in the case of railway employees shall be applicable. Jurisdiction in such actions shall be under the court of the district in which the defendant employer resides or in which his principal office is located.” 46 U. S. C. § 688.

“. . . the decisional process of arriving at a conclusion on the subject of the application of the Jones Act involves the ascertainment of the facts or groups of facts which constitute contacts between the transaction involved in the case and the United States, and then deciding whether or not they are substantial. Thus each factor is to be ‘weighed’ and ‘evaluated’ only to the end that, after each factor has been given consideration, a rational and satisfactory conclusion may be arrived at on the question of whether all the factors present add up to the necessary substantiality. Moreover, each factor, or contact, or group of facts must be tested in the light of the underlying objective, which is to effectuate the liberal purposes of the Jones Act. Bartholomew v. Universe Tankships, Inc., 263 F. 2d 437, 441.