Chap. I j.] Prognqfiics of tie Weather, 497 



The atmofphere itfelfis influenced and modified by 

 the variations of its denfity ; by its humidity ; by the 

 precipitation of the aqueous particles into rain.j by 

 the wind; by the power of electricity; and by the 

 agency of heat and cold, as remarked in the preceding 

 chapter. 



Though the fcience of predicting the weather is at 

 prefent vague and imperfect, becaufe it is but lately 

 that accurate obfervations have been made on the 

 changes of the weather, yet from what we may collect 

 from the works of De Luc, De Saufifure, Marfhallj 

 and Kirwan, we are authorized to expect fome fuc- 

 cefs in thofe inquiries. But it can hardly be fuppofed 

 that their obfervations, in the prefent (late of fcience* 

 will be fufficient to form a perfect theory, till fe- 

 conded by thofe of fucceeding times. For this falu- 

 tary end it will be neceflary to make as many obfer- 

 vations on the different figns of the weather as pofii- 

 ble, fince it is only by their combination and concur- 

 rence, that uncertainty can be removed.- 



The principal means of predicting the changes of 

 weather, and particularly with refpect to rain or 

 drought, may be reduced to feven, viz. id. From 

 the preceding ftate of the weather, ad. From the 

 undulations of the atmofphere. 3d. From the baro- 

 meter. 4th. From the appearance of the clouds. 

 5th. .From the colour of the fky. 6th. From the 

 wind. 7th. From the moon. 



I. As the caufes of every change of weather muft 

 have preceded for fome time the effect, it is in general 

 by an attention to its previous ftate, that we are 

 enabled to form the moft accurate judgment of what 

 weather is to be in future expe&edj from a feries of 



Voi. I. K k obfervations 



