THESES FROM LITERATURE. 



provided with day-data, contain a great treasure of ornithophaenological 

 facts which, when brought to light, will throw light upon territories 

 which could give us new fixed points, as Emin Pacha's series from Lado. 



No doubt a very big work, especially at the outset, and a hard 

 trial for the patience of the workers, but the very first results will 

 produce a magic effect, gradually growing with the discovery of more 

 and more interesting facts. 



With regard to the aeronautical observations published by VON 

 LUCANUS, 1 am inclined to believe that the relative altitude of 1000 

 Metres is calculated rathertoo low. We know that Birds migrate also 

 in day time, but in clear weather they are invisible, which even with 

 smaller Birds could not be the case, if they did not wander much higher. 

 On the other hand in dull weather, when the clouds are low, migrating 

 Birds may be seen at once, a fact observed by myself and others (among 

 them TiTUS Csorgey). We leave it undecided whether this low-flying 

 serves for orientation, but generally in dull weather Migration stops. 

 When the weather clears up again, even large masses of Migrants 

 disappear as if blown away. 



es 54 129 



