128 
NATURAL HISTORY OF SELBORNE. 
seen in tlie 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 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. 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 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 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 latebrce 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 flounder, and 
threatening to overwhelm them and their labours ? 
One thing is remarkable — that, after some years, the old holes are 
forsaken and new ones bored ; perhaps because the old habitations 
grow foul and fetid from long use, or because they may so abound with 
fleas as to become untenantable. This species of swallow moreover is 
strangely annoyed with fleas ; and we have seen fleas, bed-fleas {pidex 
irritans), swarming at the mouths of these holes, like bees on the stools 
of their hives. 
