his lingering flight, at so late a season of the year, never departed
from the island. Had they indulged me that autumn with a November visit,
as I much desired, I presume that, with proper assistants, I should have
settled the matter past all doubt; but though the 3rd November was a
sweet day, and in appearance exactly suited to my wishes, yet not a
martin was to be seen; and so I was forced, reluctantly, to give up the
pursuit.

I have only to add that were the bushes, which cover some acres, and are
not my own property, to be grubbed and carefully examined, probably those
late broods, and perhaps the whole aggregate body of the house-martins of
this district, might be found there, in different secret dormitories; and
that, so far from withdrawing into warmer climes, it would appear that
they never depart three hundred yards from the village.

LETTER LVI.

They who write on natural history cannot too frequently advert to
instinct, that wonderful limited faculty, which in some instances raises
the brute creation, as it were, above reason, and in others leaves them
so far below it. Philosophers have defined instinct to be that secret
influence by which every species is compelled naturally to pursue, at all
times, the same way or track, without any teaching or example; whereas
reason, without instruction, would often vary and do that by many methods
which instinct effects by one alone. Now this maxim must be taken in a
qualified sense; for there are instances in which instinct does vary and
conform to the circumstances of place and convenience.

It has been remarked that every species of bird has a mode of
nidification peculiar to itself, so that a schoolboy would at once
pronounce on the sort of nest before him. This is the case among fields
and woods, and wilds, but, in the villages round London, where mosses and
gossamer, and cotton from vegetables, are hardly to be found, the nest of
the chaffinch has not that elegant finished appearance, nor is it so
beautifully studded with lichens, as in a more rural district; and the
wren is obliged to construct its house with straws and dry grasses, which
do not give it that rotundity and compactness so remarkable in the
edifices of that little architect. Again, the regular nest of the house-
martin is hemispheric; but where a rafter, or a joist, or a cornice, may
happen to stand in the way, the nest is so contrived as to conform to the
obstruction, and becomes fla