SAND-MARTENS. 159 



And, indeed, this species seems so to delight in large waters, 

 that no instance occurs of their 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-marten discover the 

 greatest address in raising and securely fixing crusts, or shells, 

 of loam, as cunabula for their young, the bank-marten terebrates 

 a round and regular hole in the sand or earth, which is serpen- 

 tine, 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 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 despatch, and could remark how much they had scooped 

 that day, by the fresh sand which ran down the bank, and was 

 of a different 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 different depths are left unfinished at the end 

 of summer. To imagine that these beginnings were inten- 

 tionally made, in order to be in the greater forwardness for 

 next spring, is allowing, perhaps, too much foresight and 

 rerum prudentia to a simple bird. May not the cause of these 

 latebraz being left unfinished arise from their meeting in those 

 places with strata too harsh, hard, and solid for their purpose, 

 which they relinquish, and go to a fresh spot that works more 

 freely ? or may they not in other places fall in with a soil as 

 much too loose and mouldering, liable to founder, and threaten- 

 ing to overwhelm them and their labours ? 



* The bill is rather hard and sharp, well adapted for digging ; and its 

 shortness adds greatly to its strength. ED. 



