“ The provisions of the Political Code of the state of California, set forth in the certificate, do not apply to coastwise seagoing steam vessels 'not sailing under register,' and are not in conflict with the statutes of the United States. Their enforcement is simply a recognition of the limits which Congress has thus far set to the exercise of the unquestioned Federal power. The criterion is not whether the stops of registered vessels at foreign ports may be deemed en route between domestic ports, and is not to be found in the length of such stops or in the relative amount of foreign trade. ”

“ No state or municipal government shall impose upon pilots of steam vessels any obligation to procure a state or other license in addition to that issued by the United States, or any other regulation which will impede such pilots in the performance of the duties required by this title ”

“ There was no other Federal legislation upon the subject of pilots until 1852; and thus 'for more than sixty years' it was 'acted on by the states, and the systems of some of them created and of others essentially modified during that period.' Cooley v. ”