SAND-MARTINS. 201 



of the Thames, in some places below London 

 Bridge. 



It is curious to observe with what different 

 degrees of architectonic skill Providence has 

 endowed birds of the same genus, and so nearly 

 correspondent in their general mode of life ; for 

 while the swallow and the house-martin discover 

 the greatest address in raising and securely fixing 

 crusts, or shells, of loam, as cunabula for their 

 young, the bank-martin terebrates a round and 

 regular hole in the sand or earth, which is ser- 

 pentine, horizontal, and about two feet deep. 

 At the inner end of this burrow does this bird 

 deposit, in a good degree of safety, her rude 

 nest, consisting of fine grasses and feathers, 

 usually goose feathers, very inartificially laid to- 

 gether. 



Perseverance will accomplish any thing ; though 

 at first one would be disinclined to believe that 

 this weak bird, with her soft and tender bill and 

 claws, should ever be able to bore the stubborn 

 sand-bank, without entirely disabling herself ; yet, 

 with these feeble instruments, have I seen a pair 

 of them make great despatch, and could remark 

 how much they had scooped that day, by the fresh 

 sand which ran down the bank, and w T as of a dif- 

 ferent colour from that which lay loose and 

 bleached in the sun. 



In what space of time these little artists are 

 able to mine and finish these cavities, I have 

 never been able to discover, for reasons given 

 above ; but it would be a matter worthy of 

 observation, where it falls in the way of any 

 naturalist to make his remarks. This I have 

 often taken notice of, that several holes of dif- 

 ferent depths are left unfinished at the end of 

 summer. To imagine that these beginnings were 



