our, as prognostic of milder weather ; moles also 

 began to heave and work, and a manifest thaw took 

 place. From the latter circumstance we may con- 

 clude that thaws often originate under ground from 

 warm vapours which arise ; else how should subter- 

 raneous 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 ten degrees : and a clear sky shall again 

 compel it to descend to its former gage. 



And here it may be proper to observe, on what 

 has been said above, that though frosts advance to 

 their utmost severity by somewhat of a regular gra- 



* The cloud of vapour indicates increased radiation of heat and con- 

 sequent evaporation where it occurs ; as the clear sky is indicative of 

 their absence. The following figures represent the temperature in the 

 open air, at one foot and at two feet under ground, the top figures repre- 

 senting the months, those below, the mean average of each during the 

 ten years. 



It thus appears that the temperature at two feet below the surface 

 is 2° 33' higher than in the air in January ; i° 7' in February ; 0° 77' in 

 March ; 0° 25' in August ; i° 57' in September ; 2° 80' in October ; 3° 

 75' in November ; and 3° 84' in December. On the other hand, the 

 temperature is higher by 0° 21' in the open air in April ; 0° 98' in 

 May ; 1° 21' in June ; and 1° 12' in July. 



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