174 THE NATURAL HISTORY 



dormitory ; and, what is most to my present purpose, many 

 house-swallows appeared and were very alert in many places, and 

 particularly at Cobham, in Surrey. 



But as that short warm period was succeeded as well as preceded 

 by harsh severe weather, with frequent frosts and ice, and cutting 

 winds, the insects withdrew, the tortoise retired again into the 

 ground, and the swallows were seen no more until the tenth of 

 April, when, the 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 not 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 them- 

 selves again in the first week of November, and often on the fourth 

 day of that month only for one day ; and that not as if they were 

 in actual migration, but playing about at their leisure and feeding 

 calmly, as if no enterprize of moment at all agitated their spirits. 1 

 And this was the case in the beginning of this very month ; for, 

 on the fourth of November, more than twenty house-martins, which, 

 in appearance, had all departed about the seventh 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 fourth was dark and mild, and soft, the wind at south- 

 west, and the thermometer at 58'i ; 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. 2 



From 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 



1 [This description well suits the swallow kind on their autumnal migration, which 

 is always leisurely. It needs an attentive observer to discover that they are actually 

 travelling, so much do they seem to dally on the way. White had apparently never 

 seen them thus travelling in sufficient numbers to attract his attention ; hence the 

 erroneous conclusion in the last paragraph of this letter. See Introduction, p. xxxv.] 



2 [I have seen the Pipistrelle, the commonest of our bats, flying in every month 

 in the year ; and whenever gnats are tempted to come forth, the bat is sure to 

 follow for a meal. Bell.} 



