44 KANSAS ACADEMY OF SCIENCE. 



hardness, absorbed the sun's heat to a very limited extent, and instead threw 

 it off into the surrounding atmosphere, raising its temperature proportion- 

 ately. The effect of this increased temperature was to set the air in motion. 

 Cooler air rushed in to fill the vacuum, to be again heated and kept in motion. 



There being comparatively no moisture in the ground to evaporate and 

 moisten the surrounding air, it remained dry, and being of greater density 

 than the moist currents above, a local stratum of hot air was formed between 

 this moist current and the earth's surface. Being by reason of its greater 

 weight unable to force its way through the lighter air above, its motion be- 

 came lateral instead of upward ; and on account of this lateral motion, the 

 air, in passing over a large area of heated surface, became intensely heated. 

 With the increased temperature came increased velocity, and hence the hot 

 winds so prevalent on the plains many years ago, and now occasionally ex- 

 perienced on and beyond our frontier of settlements. 



After sundown the earth, owing to its limited capacity for absorbing heat, 

 cooled rapidly, and the surrounding atmosphere changed from a hot, dry 

 stratum, to a cold one of greater density, but of diminished thickness. 



My theory is, that this stratum of hot, dry air, next the earth's surface, 

 insulates the ground from the moist aerial currents passing over. It is a bad 

 conductor of electricity. Electric communications between the earth and 

 the clouds are difficult to establish, because the earth, by reason of its dry- 

 ness and lack of vegetation, offers no attraction. When an electric discharge 

 from the clouds to the earth takes place, the resistance of the dry air makes 

 its severity and destructiveness many times greater than would be the case 

 were a good conductor provided ; for the better the conductor, the more 

 quietly and harmlessly are these discharges effected. 



The atmosphere of the plains is highly electrical, but owing to the insula- 

 tion referred to, discharges are more frequently made between cloud and 

 cloud, than between the clouds and the earth. When a breach has been 

 made in this insulation, and an electric discharge takes place between clouds 

 and earth, it is generally violent, and followed by rapid condensation and 

 heavy rainfall. 



Atmospheric electricity is now believed by many to be a force generated 

 by the liberation of latent heat, when the vapor in the air is precipitated 

 into clouds, or clouds into rain; it is therefore a result, and not a cause, of 

 such precipitation. I believe it, however, to be an important factor in the 

 precipitation of the water held in the clouds, but in what exact way it acts 

 beneficially, we can only surmise. 



When the clouds are charged with positive, and the earth with negative 

 electricity, discharges from one to the other invariably follow. The rapidity 

 of the discharge through the air creates a vacuum which sets the air in mo- 

 tion. Its equilibrium has been disturbed, and before readjustment takes 

 place, a portion of the moisture is condensed and parted with in the form 

 of rain. 



