35o THE STRUCTURE AND LIFE OF BIRDS chap. 



The occasional occurrence of a rather wild theory 

 does not much detract from the merit of the book. 



In 1880 the British Association appointed a com- 

 mittee to investigate the migration of birds, and with 

 the help of the keepers of lighthouses, against which 

 the migrants often dash themselves, the committee 

 have accumulated a vast body of facts, some of which 

 have already been published. But the work of 

 analysing the facts has not yet been completed. 

 When it is, our knowledge of the subject will, probably, 

 be much advanced. Even then it must be very defec- 

 tive, if only for this reason, that nearly all the 

 observations are made in the northern hemisphere. 

 Observers are wanted in North and South Africa, and 

 owing to the absence, or the great paucity, of them, it 

 is probable that there will long be a great blank in our 

 knowledge of migration. 



Ordinary people, who have no special opportunities, 

 who do not live in Heligoland, or Malta, or the Ber- 

 mudas, or keep a lighthouse, and who cannot travel to 

 particularly favoured spots, can yet see a good deal of 

 migrant birds. They can watch for the coming of the 

 Swallow, the Nightingale, the Cuckoo, the ChiffcharT, 

 and a host of others in spring. When the woods 

 have long been almost silent save for the song of the 

 Thrush and the Robin, there comes a chorus of voices 

 resounding on all sides and most of the singers are 

 migratory birds. It is difficult to see their coming, 

 for it is usually at night. You get up in the morning 

 and you find the Swallow comfortably catching the 

 flies of his northern home and the Blackcap pro- 

 claiming his arrival in his favourite covert. In autumn 



