In Chamberlain v. Ward (1858) 62 U.S. 548 , Mr. Justice Clifford said (at page 570): "Steamers navigating in the thoroughfares of commerce must have constant and vigilant lookouts stationed in proper places on the vessel, and charged with the duty for which lookouts are required, and they must be actually employed in the performance of the duty to which they are assigned. To constitute a compliance with the requirements of law, they must be persons of suitable experience, properly stationed on the vessel, and actually and vigilantly employed in the performance of the duty; and for a failure in either of those particulars, the vessel and her owners are responsible."