NATURAL HISTORY OF SELBORNE. 63 



themselves very well, but never bred. Whether this 

 circumstance will prove anything either way I shall not 

 pretend to say. 



I return you thanks for your account of Oressi Hall ; but 

 recollect, not without regret, that in June 1746 I was 

 visiting for a week together at Spalding, without ever 

 being told that such a curiosity was just at hand. Pray 

 send me word in your next what sort of tree it is that 

 contains such a quantity of herons' nests ; and whether the 

 heronry consists of a whole grove of wood, or only of a few 

 trees. 



It gave me satisfaction to find we accorded so well about 

 the caprimulgus ; all I contended for was to prove that it 

 often chatters sitting as well as flying ; and therefore the 

 noise was voluntary, and from organic impulse, and not 

 from the resistance of the air against the hollow of its 

 mouth and throat. 



If ever I saw anything like actual migration, it was last 

 Michaelmas Day. I was travelling, and out early in the 

 morning : at first there was a vast fog ; but, by the time 

 that I was got seven or eight miles from home towards the 

 coast, the sun broke out into a delicate warm day. We 

 were then on a large heath or common, and I could discern, 

 as the mist began to break away, great numbers of swallows 

 (Hirundines rusticce) clustering on the stunted shrubs and 

 bushes, as if they had roosted there all night. As soon as 

 the air became clear and pleasant they were all on the 

 wing at once ; and, by a placid and easy flight, proceeded 

 011 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 

 swallow kind disappear some and some gradually, as they 

 come, for the bulk of them seem to withdraw at once ; 



