The Natural History of Selborne 371 



thaws often originate under ground from warm vapours which arise ; 

 else how should subterraneous animals receive such early intimations 

 of their approach. Moreover, we have often observed that cold 

 seems to descend from above ; for when a thermometer hangs abroad 

 in a frosty night, the intervention of a cloud shall immediately raise 

 the mercury 10; and a clear sky shall again compel it to descend 

 to its former gage. 1 



And here it may be proper to observe, on what has been said 

 above, that though frosts advance to their utmost severity by some- 

 what of a regular gradation, yet thaws do not usually come on by as 

 regular a declension of cold, but often take place immediately from 

 intense freezing; as men in sickness often mend at once from a 

 paroxysm. 



To the great credit of Portugal laurels and American junipers, be 

 it remembered that they remained untouched amidst the general 

 havoc : hence men should learn to ornament chiefly with such trees 

 as are able to withstand accidental severities, and not subject them- 

 selves to the vexation of a loss which may befal them once perhaps 

 in ten years, yet may hardly be recovered through the whole course 

 of their lives. 



As it appeared afterwards, the ilexes were much injured, the 

 cypresses were half destroyed, the arbutuses lingered on, but never 

 recovered ; and the bays, laurustines, and laurels, were killed to the 

 ground ; and the very wild hollies, in hot aspects, were so much 

 affected that they cast all their leaves. 



By the 1 4th of January the snow was entirely gone ; the turnips 

 emerged not damaged at all, save in sunny places ; the wheat looked 

 delicately, and the garden plants were well preserved ; for snow is the 

 most kindly mantle that infant vegetation can be wrapped in : were 

 it not for that friendly meteor no vegetable life could exist at all in 

 northerly regions. Yet in Sweden the earth in April is not divested 

 of snow for more than a fortnight before the face of the country is 

 covered with flowers. 



1 This is a first indication of the importance of radiation, and of the value of 

 clouds as an earth-blanket, since so fully worked out by Tyndall. ED. 



