Chap. 1 2.] Caujes of unufual Cold. 4 gj 



From the whole of what has been ftated, it will 

 follow, that a wet fummer will generally be fucceeded 

 by afevere winter, becaufe the cloudinefs of the feafon 

 will prevent the earth from receiving a due portion of 

 heat, and becaufe the increafed evaporation will con- 

 tribute to leffen the quantity already lodged there. 

 Much will, however, depend upon other circumftances, 

 and particularly upon the courfe of the wind. 



Unufual cold in fummer is produced ift. From 

 the long continuance of eafterly or northerly winds. 



adly. From frequent and heavy rains, which are fol- 

 lowed by a confiderable evaporation. 



jdly, JFronva long continuance of cloudy weather, 

 which prevents the earth from receiving a proper por- 

 tion of heat from the fun. 



Unufual cold in winter commonly happens 



i ft. From unufual cold or wet in the preceding 

 fummer. In January 1709, the weather was uncom- 

 monly cold, and it was remarked, that in the preceding 

 June the thermometer was near the freezing point, 

 and the ruin confiderable *. 



adly. From the immediate effect of heavy rains, 

 followed by eafterly or northern winds. This ftate 

 of things produces cold in any feafon from the increafed 

 evaporation. 



jdly. From wefterly or foutherly currents in the 

 \*pper regions of the atmofphere, while eaft or north 

 winds prevail nearer the furface of the earth. 



4thly. From the arrival of Siberian or North Ame- 

 rican winds. It has been calculated, that wefterly 

 winds may arrive in a few days from America ; and if 

 the ocean has been previoufly cooled by northern gales, 

 even thefe will feem cold to us. The Siberian winds 



Derham's Phyfic. Theol. L L c. 3. 



I i 2 will, 



