46 BRITISH BIRDS. 



conditions at the northern side of the Levant from August 

 to October, 1906 (Figures IV. and V.), may reasonably 

 be considered to provide an explanation of the irregu- 

 larity of migration arrival at Port Said during that 

 period ; an irregularity which, with the continuously 

 favourable weather conditions at the latter place, seemed 

 so illogical. 



In the diagrams (Figures IV. and V.), I have chosen 

 the Constantinople district, merely because it is the only 

 place near the north side of the Levant whose meteoro- 

 logical data I have been able to obtain. I should have 

 wished to get the same for Cyprus and several points in 

 Asia Minor as well ; however, I think the Constantinople 

 weather may fairly be assumed to represent more or less 

 the weather which a large proportion of the migrants 

 arriving at Port Said actually experienced at the point 

 of departure for their flight across the Mediterranean. 



Referring to the diagrams, it will be seen that even at 

 the end of August the Constantinople weather showed 

 signs of breaking up, in September about nine of the 

 days were unfavourable to migration, and in October 

 the weather became very unsettled, whereas at Port 

 Said there was not a single day unfavourable to migra- 

 tion the whole of this time. At Constantinople the 

 atmosphere was much moister than at Port Said, and 

 the temperature much lower, in August averaging about 

 10 degrees lower, in September 15 degrees, and in 

 October as much as 20 degrees. 



Figure IV. gives, side by side with the weather chart, 

 a graphic representation of the progress of migration 

 through Port Said between the same dates, but I am 

 afraid that the notes and observations are not full enough 

 to make this as satisfactory as I could wish, and I would 

 ask therefore that this part of the diagram be taken 

 merely as suggestive of what more extended and complete 

 observations might have made conclusive. 



I would draw attention in Figure IV. to the short 

 " hitches " very noticeable at the time in migration 



