Additional Objectio7is to Redfield^s Theory of Storms. 137 



80. Onr experiments make us familiar with two processes of 

 electric discharge. In one of these electricity passes in the form 

 of sparks or flashes, in the other it may be conveyed, without 

 any perceptible evolution of light, by the alternate or successive 

 contact of intervening bodies with the excited surfaces: as for 

 instance by means of pith balls, pendala, or a blast of air. The 

 former process has lately been designated by Faraday as " disrup- 

 tive,^^ the latter as " convective'^ discharge. 



81. The disruptive process being exemplified by lightning, 

 the magnificent apparatus of nature, by means of which this aw- 

 ful phenomenon is displayed, may be supposed competent to pro- 

 duce convective discharge upon a scale of proportionable magni- 

 tude, as exhibited in tornadoes and hurricanes. 



82. As bodies oppositely electrified attract each other, a fortiori, 

 attraction must always exist between any bodies sufficiently elec- 

 trified for an electric discharge to take place between them. This 

 law may be illustrated by means of an instrument called Cull- 

 bertson's electrometer. Hence the rising of the water within the 

 track of a tornado and its subsidence on the passage of lightning, 

 as observed by Mr. Allen, near the city of Providence, R. I.,* may 

 be considered as resulting from the alternation of convective with 

 disruptive discharge. By this observation of Mr. Allen, attraction 

 is shown to have existed between an electrified stratum of air 

 coated by clouds, and the oppositely electrified water of a subja- 

 cent river. It is reasonable to infer that attraction, originating 

 in the same way, operating upon the denser stratum of the atmos- 

 phere in the vicinity of the earth, by counteracting gravitation 

 may cause that rarefaction by which houses are burst or unroof- 

 ed, and an upward current of tremendous force produced. We 



* " The most interesting appearance was exhibited when the tornado left the 

 shore and struck the surface of the adjacent river. Being within a few yards of 

 this spot I had an opportunity of accurately noting the effects produced on the sur- 

 face of the water." The circle formed bv the tornado on the foaming water, was 

 about three hundred feet in diameter. Within this circle the water appeared to be 

 in commotion, like that in a huge boiling cauldron ; and misty vapors, resembling 

 steam, rapidly arose from the surface, and entering the whirling vortex, at times 

 veiled from sight the centre of the circle, and the lower extremity of the overhang- 

 ing dark cone of vapor. Twice I noticed a gleam of lightning or of electric fluid 

 to dart through the column of vapor which served as a conductor for it to ascend, 

 from the water to the cloud. After the flash the foam of the water seemed imme- 

 diately to diminish for a moment, as if the discharge of the electric fluid had serv- 

 ed to calm the excitement on its agitated surface. 



Vol. XLiii, No. 1.— April-June, 1842. 18 



