180 HOUSE-MARTINS. 



the third and sixth, after they were supposed to 

 have been gone for more than a fortnight. They, 

 therefore, withdraw with us the latest of any species. 

 Unless these birds are very short-lived, indeed, or 

 unless they do not return to the district where they 

 are bred, they must undergo vast devastation some- 

 how and somewhere ; for the birds that return yearly 

 bear no manner of proportion to the birds that retire. 

 House-martins are distinguished from their con- 

 geners by having their legs covered with soft downy 

 feathers down to their toes. They are no songsters, 

 but twitter, in a pretty, inward, soft manner, in their 

 nests. During the time of breeding, they are often 

 greatly molested with fleas. 



LETTER LVI. 



TO THE SAME. 



RINGMER, near LEWES, Decem. 9, 1773. 

 DEAR SIR, 



I RECEIVED your last favour just as I was set- 

 ting out for this place; and am pleased to find that 

 my monography met with your approbation. My 

 remarks are the result of many years' observation ; 

 and are, I trust, true on the whole ; though I do 

 not pretend to say that they are perfectly void of 

 mistake, or that a more nice observer might not 

 make many additions, since subjects of this kind are 

 inexhaustible. 



If you think my letter worthy the notice of your 

 respectable Society, you are at liberty to lay it 

 before them ; and they will consider it, I hope, as it 

 was intended, as an humble attempt to promote a 

 more minute inquiry into natural history, into the 



