84 Notices of Tornadoes, &e. 
does not take place, founds thus an objection to electrical agency. 
I conceive that it would be unreasonable to expect a magnetic 
needle to be affected by an electrified blast of air if protected from 
its mechanical force. 
It has been shown by Faraday that without peculiar manage- 
ment, tending to prolong the reaction, the most delicately sus- 
pended needle cannot be made to diverge in obedience to the 
most powerful discharges of mechanical electricity. An electri- — 
cal spark may impart a feeble magnetism, but is too rapid and 
transient, to affect a needle. Moreover, when a needle is at right 
angles to an electric current which would be quite competent to 
influence it if parallel to it, there can be no consequent move- 
ment, since the current tends to keep it in that relative position. 
The direction of every electrical discharge inducing a tornado 
must necessarily be nearly at right angles to the needle, since it 
must be vertical, while the needle is necessarily berinontal when 
so supported as to traverse with facility 
I do not perceive any facts or ip ee in “the article by 
(Ersted, which are competent to render the phenomenon of which 
he treats more intelligible than it was rendered by the accurate sur- 
& 
es 
vey and examination of the track of the New Brunswick tornado, — 
by Pres. A. D. Bache, and Mr. Espy, in connexion with the 
accounts published by other witnesses of aes and other similar 
meteors. 
It seems to be admitted on all a ae orte Pias certain space 
there is a rarefaction of air tending to burst or unroof houses; 
that the upward blast consequent to this rarefaction, carries up all 
movable bodies to a greater or less elevation ; and that an afflux of 
air ensues from all quarters to supply the vacuity which the ver- 
tical current has a tendency to produce. Trees within the rare- 
fied area are uprooted and sometimes carried aloft, but on either 
side of it, or in front, or in the rear, are rostrata in a direction 
almost always bearing towards a point which during some patt 
of the time in which the meteor has endured has been under the 
axis of the column which it formed. 
It appears to me that all the well authenticated characteristics 
enumerated by Girsted, are referable to the view of the case thus 
presented. This distinduisheed author assumes that there is 4 
whirling motion, although between American observers, this isa 
debated question. It seems in the highest degree probable that 
