268 RECREATIONS OF A NATURALIST 



printed in natural history journals are practically 

 useless. Those published under assumed names or 

 initials would be, of course, ignored by any 

 statistician taking up the subject, since they 

 neither afford evidence of the competency of the 

 reporter, nor furnish means of instituting a corre- 

 spondence should inquiries be necessary to clear up 

 doubtful statements, or elicit further information. 

 But even supposing that such reports were properly 

 authenticated, they would not serve to explain the 

 cause or causes of migration, or the faculty by 

 which it is performed ; they would at most only 

 tend to elucidate the manner in which birds 

 migrate, by fixing the line or lines of the route 

 which they take. 



In this country no one seems to have been at 

 the pains to collect and arrange the authenticated 

 records of arrival and departure with this object 

 until in 1879 ^ Committee of the British Association 

 was appointed for the purpose. But in Russia an 

 attempt of the kind was made in 1855 by Dr von 

 Middendorf, who published at St Petersburg an 

 important treatise on the subject.^ He collated 

 the records of the arrival of migratory birds through- 

 out the Russian empire, and endeavoured to trace 

 the lines of simultaneous arrival (as indicating the 

 route taken) by ascertaining the average date of 

 arrival of each species at localities where observa- 

 tions had been regularly taken, and connecting 



^ Die Isepiptesen Russlands. 7gog = equalis ; e'^i-rrrrisig = 

 advolatus, or, as we may term it, the lines of simultaneous 

 arrival. 



