212 THE NATURAL HISTORY 



put a bird occasionally ; so that you may see a goldfinch or a 

 linnet hopping as it were in the midst of the water, and the 

 fishes swimming in a circle round it. The simple exhibition of 

 the fishes is agreeable and pleasant ; but in so complicated a 

 way becomes whimsical and unnatural, and liable to the objection 

 due to him, 



" Qui variare cupit rera prodigialiter unam." l 



I am, &c. 



LETTER LV. 



TO THE SAME. 



October 10, 1781. 

 DEAR SIR, 



I THINK I have observed before that much the most considerable 

 part of the house-martins withdraw from hence about the first 

 week in October ; but that some, the latter broods I am now 

 convinced, linger on till towards the middle of that month : and 

 that at times, once perhaps in two or three years, a flight, for 

 one day only, has shown itself in the first week of November. 



Having taken notice, in October 1780, that the last flight was 

 numerous, amounting perhaps to one hundred and fifty ; and that 

 the season was soft and still ; I was resolved to pay uncommon 

 attention to these late birds ; to find, if possible, where they 

 roosted, and to determine the precise time of their retreat. 

 The mode of life of these latter hirundines is very favourable to 

 such a design ; for they spend the whole day in the sheltered 

 district, between me and the Hanger, sailing about in a placid, 

 easy manner, and feasting on those insects which love to haunt a 

 spot so secure from ruffling winds. As my principal object was 

 to discover the place of their roosting, I took care to wait on 

 them before they retired to rest, and was much pleased to find 

 that, for several evenings together, just at a quarter past five in 

 the afternoon, they all scudded away in great haste towards the 

 south-east, and darted down among the low shrubs above the 

 cottages at the end of the hill. This spot in many respects 

 seems to be well calculated for their winter residence : for in 



i [Hor., De Arte Poetica, 29.] 



