212 
[LETT. 
into tlie ground, and the swallows w^ere seen no more until the 
loth of April, when tlie rigour of the spring abating, a softer 
season began to prevail. 
Again, it appears by my journals for many years past, that 
house-martins retire, to a bird, about the beginning of October ; 
so that a person very observant of such matters would conclude 
that they had taken their last farewell : but then, it may be 
seen in my diaries also that considerable flocks have discovered 
themselves again in the first week of N"ovember, and often on 
the fourth day of that month only for oue day ; and that not as 
if they were in actual migration, but playing about at their 
leisure and feeding calmly, as if no enterprise of moment at all 
agitated their spirits. And this was the case in the beginning 
of this very month ; for, on the 4th of N'ovember, more than 
twenty house-martins, which, in appearance, had all departed 
about the 7th of October, were seen again, for that one 
morning only, sporting between my fields and the Hanger, and 
feasting on insects which swarmed in that sheltered district. 
The preceding day was wet and blustering, but the 4th was 
dark and mild, and soft, the wind at south-west, and the ther- 
mometer at 58J°; a pitch not common at that season of the 
year. Moreover, it may not be amiss to add in this place, 
that whenever the thermometer is above 50*^ the bat comes 
flitting out in every autumnal and winter month. 
Trom all these circumstances laid together, it is obvious that 
torpid insects, reptiles, and quadrupeds, are awakened from 
their profoundest slumbers by a little untimely warmth; and 
therefore that nothing so much promotes this death-like stupor 
as a defect of heat. And farther, it is reasonable to suppose 
that two whole species, or at least many individuals of those 
two species, of British hirundines, do never leave this island at 
all, but partake of the same benumbed state : for we cannot 
suppose that, after a month's absence, house-martins can return 
from southern regions to appear for one morning in ISTovember, 
or that house-swallows should leave the districts of Africa to 
enjoy in March the transient summer of a couple of days. 
Selborin^e, Nov. 22, 1777. 
