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star and planet, and that these are important factors in migration there can be no 

 doubt; but to what extent stars and planets act as actual guiding points we shall 

 never be able to tell, although, we know that when the sky is obscured with heavy 

 clouds, or in fogs, birds most frequently lose their way, and when the stars again 

 become visible, or the moon rises, speedily appear to find the right course again. 



For an explanation of the first causes which brought about this great periodic 

 movement across the North Sea to the shores of Great Britain, we should probably 

 have to go back to a period when the distribution of land and water in Europe was 

 very different to what it now is, and when there was no North Sea, and the western 

 coast-line of the great continent was conformable with what is now known as the 

 hundred-fathom line off the coast of Iceland — a coast, which on one hand touched 

 Scandinavia, and on the other, was linked with the Spanish Peninsula. 



There are about ninety species of plants, common alike to south-western England 

 and Ireland, and to the Pyrenean and Italian region. They represent an old flora, 

 no longer adapted to the country — a flora of warmth and sunshine— and now dying 

 out under the advance of hardier and more vigorous species. These may be regarded 

 as the last floral relics of the submerged land — a semi-tropical western land, whose 

 plants and flowers were not of Scandinavian origin, but derived from Southern Europe. 



Great as at present the contrast between the winters of England and Eastern 

 Europe, the difference would in those remote ages be much more marked — arctic 

 cold on the one hand, and semi-tropical warmth on the other. Birds, on the approach 

 of winter, would naturally draw away from the intense cold of Central and Eastern 

 Europe to seek warmth and food in the regions of the west, — a wide belt of land 

 facing the Atlantic, which would then receive the full benefit of the warm equa- 

 torial wash, and enjoy an almost perpetual summer. This habit once formed, would, 

 by the very necessities of existence and struggle for life, be continued. 



Gradually the land now occupied by the North Sea has been withdrawn from 

 beneath the migratory flocks. Year after year the middle passage becoming wider 

 and more perilous ; yet, the great periodical movement once established would be 

 continued to the present time. 



Small birds, like Regtdus cristaius and the Paridae, do not cross great breadths 

 of water from choice. They would doubtless prefer a migration overland, from field 

 to field, or bush to bush, or closely following some old established coast-line. Why 

 then, except on some such hypothesis as stated, should they cross the North Sea, 

 not only at its narrowest parts in the Straits, but also in the widest portion from 

 Elbe to Humber, or the Danish coast to the Pentland Filth and Scotch Islands? 

 What is it impels our autumn visitors to seek these shores, — the young, weeks in 

 advance of the parents, launching out westward, across what, for anything they can 

 possibly know to the contrary, might prove an Atlantic, an ocean without a 

 further shore*? 



In conclusion, we would wish to point out the present incompleteness of our 

 information and how much more remains to be done. Mr. W. Eagle Clarke, of the 

 Science and Art Museum, Edinburgh,' has undertaken the laborious task of preparing 

 a digest of the nine reports from 1879 to 1887, by an examination de novo of the 

 immense mass of schedules sent in by the light-keepers, and a systematic tabulation 

 of the facts on a method that permits the realising the importance or otherwise of 

 each separate movement. When this is completed, the results will be laid before the 

 chief promoters in the enquiry, the British Association, at their annual meeting, 

 and we trust the information may also subsequently be presented to yur august 

 Congress. — Great Cotes, IGtli March, 1891. 



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