K>8 NATURAL HISTORY 



abounding, but near vast pools or rivers ; and in particular 

 it has been remarked that they swarm in the banks 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 serpentine, horizontal, and about two feet deep. 



SAND MARTINS COLONY AT OAKHANGER. 



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 inartifi- 

 cially laid together. 



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 dispatch ; and could remark how much 

 they had scooped that day by the fresh sand which ran down 



