362 WRITINGS OF JOSEPH HENRY. [1855- 



this conductor a constant convective discharge of electricity 

 will take place, and all the phenomena described by Dr. 

 Hare will be exhibited. 



In this view of the nature of the tornado or water-spout, 

 although we adopt with Franklin and Espy, as the character- 

 istic of the commotion of the atmosphere, the rushing up- 

 ward in the form of a column (on the principles of hydro- 

 statics) of a stratum of heated and moist air which had ac- 

 cumulated at the surface of the ground, yet the phenomena 

 are modified and increased in number b}'^ the great amount 

 of electricity which must be evolved by the simple action of 

 the continued elevation of new portions of a constant stream 

 of moist air. Since the conductor in the case of the tornado 

 or water-spout, extends downward near to the earth, and 

 the discharge is continually taking place, the cloud which is 

 spread out immediately above will be negatively electrified, 

 and the upper portion of the cloud, as exhibited in Figure 

 19, will be wanting. The greater or less degree of conduc- 

 tion of the depending spout will vary the phenomena and 

 give rise to the different appearances which have been seen 

 at the surface of the water. When the conductor does not 

 quite reach to the earth visible discharges of electricity will 

 be exhibited, and the surface of water will be attracted up- 

 ward. When the conducting material of the spout touches 

 the surface of the water, the liquid will be depressed. 



That the rushing up of the air with intense violence does 

 take place in the column of a land or water-spout is abund- 

 antly proved by direct observation, and that electricity can- 

 not be the cause of this action, but is itself an effect, is 

 proved by the fact, that since the co-umn of moist air ex- 

 tends to the earth, discharges of the fluid must be made 

 through it which would soon exhaust the cloud, were it not 

 constantly renewed. In some instances the meteor has been 

 known to continue its destructive violence along a narrow 

 line of more than two hundred miles in length. To merely 

 refer this prolonged action to a whirling motion of the air, 

 without attempting to explain on known principles of science, 

 the renewed energy of the rotation, is to rest satisfied with 

 a very partial anlysis of the phenomenon. 



