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TRANSACTIONS OF THE ILLINOIS 



their contents over the wettest areas of soil, and leaving the driest still 

 unblest, even when the storm-center passes directly over them, that the 

 people of one State or county under a deluge cannot be sure that their 

 friends in a near-by State or county are receiving even a Dives' drop. 



Hence our present general announcements, even from the highest 

 authorities, so invaluable to the sailor, are of no practical use to the 

 farmer, except as they lead him personally to observe more closely and 

 successfully the common and ordinary signs of storms, and the periods 

 of their probable approach. 



This condition of things is certain to continue until both our sphere 

 and our methods of observation are greatly enlarged and improved. 



It is evident that the causes which really determine the changes in 

 the weather are not simple and homogeneous, but exceedingly manifold 

 and various. They are in general Astronomic, Telluric, Oceanic and 

 Aerial in their manifestations. 



(i) Astronomic , as evolving the greater and lesser periodic cycles, 

 years and seasons, such as the great cycle in the ecliptic of about 22,000 

 years ; of the sun's spots of eleven or twelve years ; the reputed seven years 

 of alternating floods and drouths, and our regularly returning seasons, 

 summer and winter, day and night, etc. 



(2) Telluric, or the earth as affected by the seasons : summer and 

 winter, spring and fall ; its forests, denudations, mountains, hills and 

 plains ; its snow-lines from time to time ; its great areas of greatest wet 

 and greatest drouth, as indicated by the stages of the waters in the 

 great rivers ; the antecedent rains or snow-falls over given areas ; its 

 changing reciprocal electric condition over given areas, as related to the 

 clouds in the air; its great constant and variable electric circuits, or 

 changes of electrical conditions within itself and upon its surface ; its 

 internal and surface heat, over given areas, etc. 



(3) Oceanic, as supplying water for evaporation, and through its 

 varying temperature and its currents generating or varying the course of 

 storms and changing the temperature of all lands from the Equator to the 

 Poles. 



(4) Aerial, or the movements, temperature, moisture and pressure 

 of the air. 



But we should bear in mind that none of these exhibitions of mere 

 phenomena are real causes, but all alike are only phenomenal effects or 

 the mere antecedents, the mere playthings, of some unseen power or 

 powers, called forces, that lie behind them and eternally invert, control, 

 dandle and play with them, as the viewless winds do with the dust in 

 the air. These unseen causal forces or powers we call heat, light, elec- 

 tricity, magnetism, attraction, etc., according to the phenomena they 

 produce. 



Now, whether the causal power or force which we call heat or elec- 

 tricity, or both together, or some other mode of force wholly unknown to 

 us, is the dominant and controlling influence in storms, it seems certain to 

 me that the condition of the earth's surface, as wet or dry, cold or hot, 

 covered with snow or bare, must exert a great influence on these causal 



