68 NATURAL HISTORY 



clear and pleasant they all were on the wing at once ; and, by 

 a placid and easy flight, proceeded on southward towards the 

 sea : after this I did not see any more flocks, only now and 

 then a straggler. 



I cannot agree with those persons that assert that the swal- 

 low kind disappear some and some gradually, as they come, 

 for the bulk of them seem to withdraw at once : only some 

 stragglers stay behind a long while, and do never, there 

 is the greatest reason to believe, leave this island. Swallows 

 seem to lay themselves up, and to come forth in a warm day, 

 as bats do continually of a warm evening, after they have dis- 

 appeared for weeks. For a very respectable gentleman assured 

 me that, as he was walking with some friends under Merton- 

 wall on a remarkably hot noon, either in the last week in 

 December or the first week in January, he espied three or four 

 swallows huddled together on the moulding of one of the 

 windows of that college. I have frequently remarked that 

 swallows are seen later at Oxford than elsewhere : is it owing 

 to the vast massy buildings of that place, to the many waters 

 round it, or to what else? 



When I used to rise in a morning last autumn, and see the 

 swallows and martins clustering on the chimneys and thatch 

 of the neighbouring cottages, I could not help being touched 

 with a secret delight, mixed with some degree of mortification: 

 with delight to observe with how much ardour and punctuality 

 those poor little birds obeyed the strong impulse towards mi- 

 gration, or hiding, imprinted on their minds by their great 

 Creator ; and with some degree of mortification, when I re- 

 flected that, after all our pains and inquiries, we are yet not 

 quite certain to what regions they do migrate ; and are still 

 farther embarrassed to find that some do not actually migrate 

 at all. 



These reflections made so strong an impression on my ima- 

 gination, that they became productive of a composition that 

 may perhaps amuse you for a quarter of an hour when next I 

 . have the honour of writing to you. 



