3 io SUMMER 



colder, as a rule, is the hour before dawn. The pools of 

 cold air that are found in hollows on hot summer nights are 

 partly due to the descent of the coldest air to the lowest 

 ground as the temperature falls ; but partly it is due to the 

 direct power of the sun, which sucks up the moisture in the 

 ground to a greater depth than in years of less sunshine. 

 In the July nights one climbs in a few yards from the damp 

 chilly air in the hollows to the warm layers of the upper 

 slopes and the open fields. The transition corresponds to 

 the daylight boundary between grass brown and dead to the 



very root, and turf which still retains a sort of under-fur of 

 green. Often at dawn in the hottest summer weather high 

 ranges of hills are also wrapped in mist, though the lowlands 

 may be almost clear. This, too, is due to the evaporating 

 power of the sun, which fills the higher air with masses of 

 vapour which condense at night where they meet the colder 

 layers of the heights. The fog is often thick enough to drip 

 profusely from the trees ; and by midday, when the white 

 road along the hills is lapped in heat, it is curious to see the 

 dust beneath each tree thickly pitted by the drops. After 

 a light shower of rain the road outside the tree's shelter is 

 pitted ; but in the white night-fog the tree itself sheds rain, 

 while the earth around it is dry. 



