172 NATURAL HISTORY OF SELBORNE. 
Here are in this parish, in the sand-pits and banks of the lakes 
of Woolmer forest, several colonies of these birds, and yet they 
are never seen in the village; nor do they at all frequent the 
cottages that are scattered about in that wild district. The only 
instance I ever remember where this species haunts any building 
is at the town of Bishop’s Waltham, in this county, where many 
sand-martins nestle and breed in the scaffold-holes of the back- 
wall of William of Wykeham’s stables ; but then this wall stands 
in a very sequestered and retired enclosure, and faces upon a large 
and beautiful lake. 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 architec- 
tonic 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. 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 anything ; 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 seena 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 be- 
ginnings were intentionally 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 
