292 PROCEEDINGS OF THE AMERICAN ACADEMY 



" When a trunk reaches down from a cloud, electrically ex- 

 cited, the discharge of electricity must resemble in character 

 that from a point. With our small machines, the electricity, 

 escaping from a pointed rod attached to the prime conductor, 

 electrifies the air, and produces a blast sufficient to turn a 

 small wheel. Yet Faraday estimates that several hundred 

 thousand, or even million, turns of such a machine, are required 

 to give the amount of electricity contained in a single flash of 

 lightning ; and the clouds from which the trunk of the tornado 

 descends may perhaps furnish many hundred such flashes. 

 On the scale of nature, therefore, this may become an intense 

 axial force, producing powerful currents of air and other con- 

 vective eff"ects. If a silent electrical discharge between a great 

 mass of clouds and the earth should be excited at a given 

 point, the formation and descent of the trunk would almost 

 necessarily follow, and a cause of permanent axial action 

 would be established, 



" The clouds, also, are huge floats, having a certain buoyancy, 

 and liable to be drawn down towards the earth by electrical 

 attraction. They must exert an equal reaction upon bodies 

 on the surface of the earth. With our small machines, light 

 bodies are raised in opposition to gravity, by an excited body 

 held at some distance above them. On the immense scale of 

 nature, this may also become a powerful cause antagonistic to 

 the gravity of bodies, especially near the axis of convective 

 discharge, where the inductive power of great masses of clouds 

 is concentrated. 



" These electrical causes are not presented as a theory of the 

 tornado, to the exclusion of other active forces. They are, 

 however, primary in their character, and based on familiar 

 facts and analogies. They should therefore be subjected to 

 mathematical calculation before they are set aside as insuf- 

 ficient to produce powerful mechanical effects." 



Mr, J. H. Abbot, in addition to the theoretical objections 

 which had been urged against the whirlwind theory, stated 

 several observed facts, and referred to various forms assumed 



