XXXIV.] OF SELBORNE. 103 



Some extracts from your ingenious " Investigations of the 

 difference between the present temperature of the air in 

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

 faction ; 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 ! 



Two swallows have appeared amidst snows and frost. 



SKLBORNE, April 12, 1770. 



LETTER XXXIV. 



TO THOMAS PENNANT, ESQ. 



LAST month we had such a series of cold turbulent weather, 

 such a constant succession of frost, and snow, and hail, and 

 tempest, that the regular migration or appearance of the summer 

 birds was much interrupted. Some, as the blackcap and white- 

 throat, did not show themselves (at least were not heard) till 

 weeks after their usual time ; and some, as the grasshopper-lark 

 and largest willow-wren, have not been heard yet. As to the 

 fly-catcher, I have not seen it ; it is indeed one of the latest, 

 but should appear about this time : and yet, amidst all this 

 meteorous strife and war of the elements, two swallows dis- 

 covered themselves as long ago as the llth of April, in frost 

 and snow ; but they withdrew quickly, and were not visible 

 again for many days. House-martins, which are always more 

 backward than swallows, were not observed till May came in. 



Among the monogamous birds several are to be found single 

 after pairing-time, and of each sex : but whether this state of 

 celibacy is matter of choice or necessity, is not so easily discover- 

 able. When the house-sparrows deprive my martins of their 

 uests, as soon as I cause one to be shot, the other, be it cock 



