A PARTICULAR REVIEW 21 



mended, cannot by any indulgence be considered 

 musical ; yet it is pleasantly associated with ' the 

 sweet o' the year'. These three birds are all in 

 Thomson's note-book. It is the flight of the swallow, The 

 its unresting industry, that takes his eye : he stands to 

 watch it as it * sweeps the slimy pool, to build its 

 hanging house intent ' ; but it is the mysterious dis- 

 appearance of the bird in the hinder end of harvest 

 130 that engages his mind. There are the two theories, 

 hibernation and migration, to explain this disappear- 

 ance. Thomson is acquainted with both. If hiberna- 

 tion be the correct theory, he accounts for their 

 congregated play in the air among the parting gleams 

 of autumn as a kind of carnival before Lent 



Ere to their wintry slumbers they retire, 



In clusters hung, beneath the mouldering bank, 



And where, unpierced by frost, the cavern sweats ; 



but he inclines rather to the theory of migration, which 

 uo conveys the swallow people, ' with other kindred birds 

 of season/ into warmer climes where they enjoy the 

 pleasures of active life, and 



Twitter cheerful till the vernal months 

 Invite them welcome back. 



He is thus even more advanced in his scientific 

 knowledge of the subject than Gilbert White, who held 

 the opinion, a generation after Thomson's death, that 

 ' though most of the swallow kind may migrate, yet 

 some do stay behind and hide with us during the 

 150 winter '. 



Thomson's one remark about the cuckoo is on its The 

 hollow note, the sound of which (as of a horn faintly Gucjco - 

 blown from Elfland) is one of the signs that spring has 



