Temperature of the Summer a7id JVinter Seasons. 213 



I call the mathemntical temperature. But in most cases 

 this temperature is far from agreeing with the temperature 

 really ohserved, and which 1 therefore call the real tempe- 

 rature ; this I take at a mean, and not at its maxhmim, 

 which I could not always discover, and is more fugitive 

 and contingent. These temperatures I exhibit in two sepa- 

 rate tables, the first indicating those of the vernal equinox 

 and of the northern tropic or m.dsummer, and the second 

 those of the autumnal equinox and the southern tropic or 

 midwinter^ over the Atlantic or standard ocean in our he- 

 misphere. 



Tahle the First. 



In this table we see, 1 . That during the vernal equinox 

 the heat differs but little from the mean heat really observed 

 in all latitudes, and perhaps still less from the maximum of 

 real heat ; yet, except in latitude 80°, it is alwa\s higher, 

 both from the quantity of rays lost in passing through the 

 air, and from the quantity reflected by water and the fre- 

 quent interposition of clouds, &c, 



9. We see that the astronomical heat constantly in- 

 creases with the height of the latitudes, as the duration of 

 the solar rays more than compensates for their obliquity 

 when the sun is in the northern tropic ; but the real heat; 

 decreases as the latitudes increase, because this theoretic 

 compensation docs not take place from the inlcrjxjsition of 

 clouds and the access of cooler winds, and the increased re- 

 flgction from the surface of the water. 



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The 



