112 THE NATURAL HISTORY 



by opening a female during the laylng-time. If more than 

 one was come down out of the ovary, and advanced to 

 a good size, doubtless then she would that spring lay more 

 than one. 



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



Your supposition that there may be some natural 

 obstruction 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 

 caprimulgus, or fern-fowl ; you were, I find, acquainted with 

 the bird before. 



When we meet, I shall be glad to have some conversa- 

 tion with you concerning the proposal you make of my 

 drawing up an account of the animals in this neighbour- 

 hood. 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 unsup- 

 ported 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," etc. have fallen in my way; and gave me 

 great satisfaction : they have removed the objections that 

 always rose 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. 



