Before the invention of the mariner's compass, the Phoenician, the Greek, and the early Italian navigators were compelled to creep from headland to headland, without venturing to quit the shore—except when an island, so near as to be distinctly seen from the continent, offered them an equally secure retreat from the violence of an accidental tempest. Yet, the bolder Norwegians, though exposed to far greater perils, from the habitual inclemency of a high northern latitude, and from the frequent cloudiness of their atmosphere, were in the habit of attempting, and often with success, a voyage of some length upon the ocean. It may be supposed that a patient observation of natural phenomena, attention to the flight of migratory birds and to the direction of currents, and some few simple devices which, being no longer necessary, are now forgotten, served as substitutes for the more valuable guides of modern navigation. Of one of the devices here enumerated, it is related that when Flok, a famous Norwegian navigator, was about to set out from Shetland for Iceland, then called 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 part of his way, he threw up one of his crows, which, seeing land astern, flew to it; whence Flok, concluding that he was nearer to Shetland (or perhaps FaroË) than 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 greater part of his way, another crow was sent out by him, which, seeing land ahead, immediately flew for it; and Flok, following his guide, fell in with the east end of the island. Such was the simple mode of steering their course, practised by those bold navigators of the stormy northern ocean. This story at once and strikingly recalls the use made of birds by the first sea captain of whom we read—Noah; but such expedients evidently could not be supposed to have inspired the old northern navigators with the courage and confidence that enabled them, as there is reason to believe, to discover America before Columbus.