XXXIY,] 
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 my 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. 
Selborne, April 12, 1770. 
LETTEK 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 11th 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 
nests, as soon as I cause one to be shot, the other, be it cock 
