184 The Natural History of Se I borne 



cuckoo lays one or two eggs, or more, in a season, by opening 

 a female during the laying time. If more than one was come 

 down out of the ovary, and advanced to a good size, doubt- 

 less then she would that spring lay more than one. 1 



I will endeavour to get a hen, and to examine. 



Your supposition that there may be some natural obstruc- 

 tion in singing birds while they are mute, and that when this 

 is removed the song recommences, is new and bold ; I wish 

 you could discover some good grounds for this suspicion. 



I was glad you were pleased with my specimen of the capri- 

 mulgus, or fern-owl ; you were, I find, acquainted with the 

 bird before. 



When we meet I shall be glad to have some conversation 

 with you concerning the proposal you make of my drawing up 

 an account of the animals in this neighbourhood. Your 

 partiality towards my small abilities persuades you, I fear, 

 that I am able to do more than is in my power : for it is no 

 small undertaking for a man unsupported and alone to begin 

 a natural history from his own autopsia ! Though there is 

 endless room for observation in the field of nature, which is 

 boundless, yet investigation (where a man endeavours to be 

 sure of his facts) can make but slow progress ; and all that 

 one could collect in many years would go into a very narrow 

 compass. 



Some extracts from your ingenious " Investigations of the 

 Difference between the Present Temperature of the Air in 

 Italy," &c., have fallen in my way ; and gave me great satisfac- 

 tion : they have removed the objections that always arose in 

 my mind whenever I came to the passages which you quote. 

 Surely the judicious Virgil, when writing a didactic poem for 

 the region of Italy, could never think of describing freezing 

 rivers, unless such severity of weather pretty frequently 

 occurred. 



P.S. Swallows appear amidst snows and frost. 



1 This is physiologically incorrect. Only one ovum is contained in 

 the oviduct of any bird at one time ; but the cuckoo, as already noted, 

 does lay several eggs in each season. Ep. 



