82 THEO RT of RAIN. 



or commotion in the atmofphere that will be followed by this 

 effect ', for* though mixture of the atmofphere be a neceffary 

 condition in the caufe of rain, it is not the only condition ; 

 and, therefore, the fame appearances, in relation to the winds, 

 and to the different temperatures of the atmofphere, may be 

 obferved, while rain, as the effect, may either follow or not, 

 according as the third condition may or may not take place : 

 That is, that the mixed atmofphere be fufficiently faturated with 

 vapour or humidity ', which is a thing that cannot perhaps be 

 made the fubject of our obfervation. 



6. RAIN happens in the hotteft weather, and in every degree 

 of temperature, down to the freezing point ; it requires, there- 

 fore, much attention to obferve the changes of temperature in 

 the atmofphere that ufually attend the production of rain, in 

 all this range of the thermometer from 80. to 32. But, about 

 the freezing point, the effects of heat and cold are fo manifeft, 

 in the fluidity and congelation of water, that a perfon can 

 hardly avoid making obfervations which will tend to confirm 

 the theory. 



WHEN, after fettled froft, it begins to fnow, the cold is al- 

 ways found to relent, and the thermometer to rife to the freezing 

 point, or nearly, however low it may have been before. But 

 after the fnow has fallen, and the fky becomes clear, the cold in- 

 creafes, until it again refumes its former intenfity, or even pro- 

 ceeds to a greater degree. This is an appearance which is eafily 

 explained in the theory ; and it is an appearance which every 

 perfon, who can make an obfervation, has it frequently in his 

 power to verify. 



7. THE climate which we inhabit has, for character, tempe- 

 rance in extreme ; our winters and our fummers differ but lit- 

 tle from each other in their mean temperatures. There is, in 

 this ifland, but little fteady determination for the wind, which, 

 in general, is extremely variable. The variable nature of our 

 winds cannot be the effect of the temperance of our climate > 



but 



