the severe cold of December, 1784, the thermometer 

 fell many degrees lower in the valley bottoms than 

 on the hills. He had not observed that the very 

 cold air on such occasions settles down into the val- 

 leys and fills them like water, marking the height to 

 which it rises by a level line upon the trees or foliage. 

 It is a wonder that his sharp eye did not detect the 

 true source of heavy dew, but it did not. He 

 thought it proceeded from the effluvia of flowers, 

 which, being drawn up into the sky by the warmth 

 of the sun by day, descended again as dew by night. 



When a French anatomist announced that he had 

 discovered why the cuckoo did not hatch its own 

 eggs — namely, because the crop or craw of the bird 

 was placed back of the sternum, so as to make a pro- 

 tuberance on the belly — White dissected a cuckoo 

 for himself, and, finding the fact as stated, proceeded 

 to dissect other birds that he knew did incubate, as 

 the fern-owl and a hawk; and finding the craw situ- 

 ated the same as in the cuckoo, justly charged the 

 Frenchman with having reached an unscientific con- 

 clusion. 



In his seventv-seventh letter White clearly antici- 

 pates Darwin as to the beneficial functions of earth- 

 worms in the soil, and tells farmers and gardeners 

 that the little creatures which they look upon as their 

 enemy is really their best friend. 



Chanofes are slow in Engrland. All the essential 

 features of Selborne remain about as they were in 



xxi 



