A MONTH ON KENTISH KNOCK LIGHTSHH^ 27 



ments. These movements, I found, did not begin in 

 earnest until a decided fall in temperature took place in 

 Western Central Europe, and this important factor was 

 the precursor of each of the pronounced movements 

 observed. Before such incentives to migration were 

 experienced, unusually high temperatures had prevailed, 

 and this was undoubtedly the reason why the movements 

 prior to 8th October had been of such a straggling and 

 feeble nature. These falls In temperature were not on 

 all occasions experienced on our shores, and this again 

 demonstrates the necessity for consulting the meteoro- 

 logical data at the place where such movements have 

 their source. 



The strongest wind prevailing when migration was 

 in progress was on 13th October, when, with a westerly 

 moderate gale blowing with a velocity of from 34 to 40 

 miles an hour, Swallows were proceeding in numbers to 

 the south-south-west, and some House-Martins to the 

 north-west — no other species being on the move. 

 Under like conditions on the 9th, Martins were the only 

 migrants observed, and were moving from north-west to 

 south-east. 



The weather conditions under which the other move- 

 ments were witnessed do not call for any special remarks, 

 for my experiences were similar to those at the Eddy- 

 stone, and supported the views already expressed in that 

 " Study " on the bearing of meteorology on bird- 

 migration where the sea-passage is a short one. 



As at the Eddystone, whenever a number of 

 individuals of a species were obtained during any 

 movement, they showed a considerable range of varia- 

 tion in their wing measurements, bearing out fully what I 



