sky? Indeed he again and again declares that migration passes unseen yet calculates the numbers observed on the darkest nights; the illumination of the lighthouse could not be sufficient to enable him to even guess at the numbers he mentions. After stating that "the whole vault of heaven was literally filled to a height of several thousand feet with these visitors from the regions of the for North," and that a certain east to west passage extended from the Faroes to Hanover, he concludes that "the view—that migrants follow the direction of ocean coasts, the drainage areas of rivers, or depressions of valleys as fixed routes of migration can hardly be maintained."
As emphatically he maintains that most observable migration over Heligoland is due east to west or west to east, though the birdstuffer Aeuckens, who supplied him with much of his information, told Seebohm that it was north-east in spring and south~west in autumn (45). Is it not perfectly evident that the geographical position of Heligoland makes it a convenient resting place for large numbers of migrants, for it is certainly true that large numbers are observed there, which pass southward and westward along the Baltic, crossing Sehleswig-Holstein and the mouth of the Elbe, or coast south along Denmark, and cross the Elbe diagonally, en route for the Dutch and French coasts and
