204 Mr. W. Eagle Clarke—^ Month 



quite close to the tower; ami thus from my elevated and 

 fixed point of observation on the gallery I was enabled to 

 gauge the height from which these birds dived with a degree of 

 accuracy not usually attainable. I witnessed many thousands 

 of dives, bvit in no case did the drops exceed a height of 

 from 130 to 140 feet. About one-fourth of the Gannets 

 seen were in immature dress, all stages being represented 

 except that of the year — a fact which is worthy of note. 



The Eddystone was an excellent station for studying the 

 weather conditions and their bearing upon bird-migration. 



Birds when performing long flights not unfrequently pass 

 from the zone of favourable weather, which is conducive to 

 their departure, to an area in which the conditions are more 

 or less unfavourable; and they are consequently recorded as 

 arriving on our coasts in the autumn under adverse circum- 

 stances. Such inauspicious instances of immigration as 

 these are apt to mislead those interested in the subject, for 

 it is not always borne in mind that it is the state of the 

 weather at the point of departure which affords the only 

 indication of the actual conditions controlling the move- 

 ments. 



At the Eddystone, owing to its contiguity to the mainland, 

 one witnessed simultaneously the movements and the meteoro- 

 logical conditions under which the birds elected to set out 

 on their passage southwards ; or if no movements took 

 place, either by day or by night, one was able, it being the 

 height of the emigratory season, to determine, in some 

 measure at least, what the weather-barriers were which 

 arrested such migrations. Thus this station was singularly 

 favourably situated — probably none more so — for observing 

 the meteorological conditions which made for or against 

 emigration. 



No movements were witnessed, either by day or night, on 

 the part of land-birds under weather conditions which could 

 be described as in the least degree unfavourable for crossing 

 the Channel. 



The wind is certainly the main factor in migration- 



