54 NATURAL HISTORY 
thern opinion (strange as it is) of their retiring 
under water. A Swedish naturalist is so much 
persuaded of that fact, that he talks, in his Calen- 
dar of Flora, as familiarly of the swallow’s going 
under water in the beginning of September, as he 
would of his poultry going to roost a little before 
sunset. . 
An observing gentleman in London writes me 
word that he saw a house-martin, on the 23d of 
last October, flying in and out of its nest in the 
Borough; and I myself, on the 29th of last Octo- 
ber (as I was travelling through Oxford), saw four 
or five swallows hovering round and settling on 
the roof of the County Hospital. 
Now is it likely that these poor little birds 
(which, perhaps, had not been hatched but a few 
weeks) should, at that late season of the year, and 
from so midland a county, attempt a voyage to 
Goree or Senegal, almost as far as the equator ?* 
I acquiesce entirely in your opinion, that, though 
most of the swallow kind may migrate, yet some 
do stay behind and hide with us during the winter. 
As to the short-winged, soft-billed birds, which 
come trooping in such numbers in the spring, I am 
at a loss even what to suspect about them. I 
watched them narrowly this year, and saw them 
abound till about Michaelmas, when they appeared 
no longer. Subsist they cannot openly among us, 
and yet elude the eyes of the inquisitive; and as 
to their hiding, no man pretends to have found any 
of them in a torpid state in the winter. But with 
regard to their migration, what difficulties attend 
* See Adamson’s Voyage to Senegal. 
