a, 
- Sedes lightning by affording a conducting communication between - 
wee 
Notices of Tornadoes, §c. 81 
for a continual discharge of electricity from those above, and that 
the difference between an ordinary thunder storm and one ac- 
companied by a tornado, consists in the presence of a conductor 
of clouds, which seem to maintain the combat between the up- 
per portion of the tornado and the ground beneath. At Chatenay 
this conductor was formed by the influence of an upper thunder 
cloud, which forced the lower portion of an inferior thunder cloud 
to descend and come into contact with the terrestrial surface.” 
Peltier concurs with me in the opinion that the tornado super- 
the terrestrial surface and thunder cloud: but he conceives that 
the cloud by its descent becomes the conductor through which 
the electric discharge is accomplished: whereas agreeably to the 
explanation which I suggested, a vertical blast of air and every 
body carried aloft contributes to form the means of communication. 
Agreeably to this suggestion the electric fluid does not pass 
conduction, but “convection,” as explained in my letter of the 
26th ult. That the idea of the Parisian savant that the cloud 
acts as a conductor is untenable, must be evident, since the light 
matter of which a cloud is constituted could not be stationary be- 
tween the earth and sky in opposition to that upward aerial cur- 
rent of which the violence is proved to be sufficient to elevate 
not only water, but other bodies specifically much heavier than 
this liquid. 
So much of the narrative of Peltier as relates to the repulsion 
between the thunder clouds, is inconsistent with any other facts 
on record respecting tornadoes which have come within my 
knowledge. It should be recollected that this part of the story 
does not depend upon the observation of the author, and may be 
due to the imagination of the witnesses whom he examined. 
The most important part of his evidence is that respecting the 
effect upon the trees, which appears to me to. demonstrate that 
they were the medium of a tremendous electrical current. 
In my memoir I noticed the injury done to the leaves of trees, 
and stated my conviction that “(as it was inconceivable that me- 
chanical laceration could have thus extended itself equally among 
the foliage, a surmise may be warranted that the change was 
effected by electricity associated with the tornado.” 
Vol. xxxyur, No. 1.—Oct.-Dec. 1839. 11 
Ye 
