214 Of the Fhiiations of the Temperature 



The different temperatures of diffcrenl summers are olti- 

 inately resolvable into the different direction of the winds 

 during those seasons and the different electrical sl.iles of the 

 atmosphere, the south oi south-east producing not only 

 clouds which intercept the sun's ravs, but also copious 

 rains or hail, which, descending from great heights and 

 occasioning a copious evaporation, cool the air to a great 

 degree. The north and north-cast, on the contrary, unless 

 immediately succeeding great rains (for then they increase 

 the evaporation), disperse the clouds, and, proceeding from 

 countries then somewhat heated, allow the sun's rays their 

 natural calefactive effect. But why winds from opposite 

 points should prevail in different years cannot be known 

 until the contemporaneous states of the atmosphere between 

 the northern tropic and the equator are known. It is pos- 

 sible that frequent hurricanes and tornadoes, during which 

 a quantity of air may be destroyed and converted into wa- 

 ter, may demand an annual supply from the north, and 

 thus occasion our north and east winds ; and the absence of 

 these phaenoracna may occasion an influx from the south, 

 if the north and cast arc summoned to a different quarter, 

 by similar causes. 



Talile the Second. 



On this table we may remark, 1. That though the ma- 

 thematical temperature of the autumnal equinox be exactly 

 the tame as that of the vernal, vet tire real is much higher, 

 as the aorthern hemisphere being cooled during the winter 

 is slowly heatedj and being heated during the summer is 

 slowly cooled. 



2. That 



