(The material of the following post predates the 1300 century, when the dry compass came into use in European sea navigation. Here the writer uses the word ‘Crow’ for the more modern, Raven.)
Amgrin Jonas tells us, that when FLOK, a famous Norwegian Navigator, was going to set out from Shetland for Iceland, then call Gardarsholm, he took on board some Crows, because the Mariner’s Compass was not yet in Use. When he thought he had made a considerable progress, he threw up one of his Crows, which, seeing Land astern, flew to it; whence FLOK, concluding that he was nearer to Shetland (perhaps rather Faroe) then any other Land, kept on his Course for some time, and then sent out another Crow, which, seeing no Land at all, returned to the Vessel. At last, having run the greatest part of his Way, a third Crow was sent out, which, seeing Land a-head, immediately flew for it; and FLOK, following his Guide, fell in with the East and of the Island. Such was the simple mode of steering their Course, practiced by these bold Navigators of the stormy Northern Ocean.
―The ancient Natives of Taprobané (Ceylon) used the same expedient when skimming along the tranquil surface of the Indian Ocean.
―‘Rural Sports.’ Volumes III. by Thomas Davison, Whitfriars, 1812.