of tlie Summer and JVlnler Seasons. 215 



2. That in consequence of this circumstance the real 

 temperature of the autunmal equinox approaches much 

 nearer to the astronomical than does that of the vernal, 

 until we arrive at latitude 70" and the higher latitudes. 



3. In all latitudes above the equator a cold approaching 

 to the astronomical is scarce ever felt at sea in winter : to 

 what can this be attributed but to the ecpiatorial edkience? 

 For other causes, viz. evaporation and the frequent inter- 

 vention of clouds, or at least haze, intercept the sun's rays, 

 and consequently should cool the air even below the astro- 

 nomical ratio which supposes the incidence of all the rays : 

 in latitudes above 20° the difference is enormous. 



4. At the distance of some hundred miles from the coasts 

 of the Atlantic, in latitudes above 40°, the cold is much 

 more moderate than the mathematical ratios indicate in 

 most years ; owing to the above-mentioned cause, and to 

 the reign of w'csterly and southerly winds, which convey 

 their heat to a considerable distance before they are cooled. 



But in latitudes between 35° and 36° a degree of cold far 

 superior to the astronomical has often been observed, and 

 particularly of late, and in countries not very distant, or 

 even bordering on the Atlantic. These extraordinan/ sea- 

 sons may be attributed partly to the absence of the superior 

 effluence, or its refrigeration in connnunicating with air re- 

 plete with vapours, and partly to the pre\alencc of east- 

 north-east winds which proceed from the interior and cold- 

 est parts of our continent ; and hence the cold of the year 

 1776, so well described by Van Swinden, seems rather to 

 have followed the order of the longitudes than of the lati- 

 tudes. Wargentin, secretary to the Koyal Academy of 

 Stockholm, informs him that the cold observed that winter 

 in Stockholm was not at all extraordinary, and expresses 

 his surprise that it should have been so rigorous in Ger- 

 many, France, 'and England. (Mem. Paris, 1776, p. 129.) 

 Nay, it appears that tlve north-east wind which raged so 

 furiously in J ioUand and at Montmorcnci, latitude 49°, on 

 the 27th (see V^an Swinden, p. 40), had not been at Peters- 

 burgh on the 18th, nor any day after; for a perfect calm 

 reigned on that day, and the high winds of the remainder 

 of the month were from the north-west. (Act. Petropol. 

 p. 382.) It is therefore probable i.hat this wind proceeded 

 obliquely fronj the eastern and southern parts of Russia, 

 and may have been derived from latitude 55" and longitude 

 40°, and originated on the Atlantic, latitude 40'; and hence 

 the utinf)st rigour of this cold was sooner perceived in the 

 eoulh of France, as Tlioulouse, Marseilles, ik,c. than in the 

 O i aior« 



