The Superior times. [volume] (Superior, Wis.) 1870-1912, 1878-08-03
LIGHTNING.
Conditions Favorable for it's Attraction
Safeguards Against Injury from
Electric Bolts,

Conditions Favorable for it's Attraction
Safeguards Against Injury from
Electric Bolts.
Under what conditions is damage from
lightning possible, and what are the
means by which the risk may be lessen
ed or avoided? An isolated tree, stand
ing either upon a wide plain or upon an
emneince, is obviously likely to determine
lightning discharge, to Z" attract the
lightning" TO use a common expression.
The top of the tree is the nearest point
to the cloud, and since the tree is a
better conductor than the air, line
drawn vertically through it to the cloud
marks the shortest and easiest course
along which the electricities may pass.
If, when the charged cloud arrives di-
rectly over this point, the tension is suf-
| fcient to overcome the resistance along
that line, a discharge Will take place,
| and the tree will be struck But If the
| tension be not sufficient, the cloud will
pass harmlessly over. Hence it appears
| that person standing during a thunder
storm beneath a tree so situated Is ex-
posed to some risk. On no account,
| therefore, should the Traveller take refuge
under an isolated tree; generally he will
| do well to avoid It's neighborhood alto
gether; but should he be Overtaken by
| the storm when on a plain with no
| shelter near, the tree may still be made
to afford him some protection. If he
| take up a position near it, but not under
its branches, he will probably escape
unhurt should the lightning descend
upon it, The safest distance from the
tree is that which is equal to its height.
To approach much nearer than this is to
incur the risk of being within the in
| tluence of the stroke; to remain at a
much greater distance away is to place
ones self in the same conditions of iSola-
! ton as the tree itself. 1t will have been re-
marked by all observers of the phe-
nomenon that whenever tree has been
struck by lightning it has generally
occupied an isolted position. In de,
scrlbIng the position as one of isolation,
! however, it is not meant that the tree
is necessarily standing alone, but that il
is not one of numerous group. When
| there are many trees together, their col
lective conductivity is often sufficient tc
cause an indestructive discharge of the
electricity. This is especially likely tc
! happen when the trees are wet with
rain, for then their surfaces are covered
with a film of water, which is n good
conductor. For this reason, the danger
| from lightning is much less after rain
has begun to fall, than before, wher
everything is dry. Itappears, therefore
that the safest situation during thun
| der-storm is in the midst of a wood, par
| ticularly if the neighborhood of the
| tallest tress be avoided. In such place
of shelter, the traveller may take refuge
in full assurance that he will there be
effectually shielded from harm. tn,
greatest risk of injury from lightning il
undoubtedly incurred by persons travel
! ing across Il wide and very fiat plain
| because in such situation they are the
only elevated objects. TO lessen the
risk, which may here be somewhat
serious, advantage should be taken of
whatever fluctuations of surface may
exist, to keep upon the lowest ground
No doubt the PROSTATE position would
in these circumstances afford greater
security than the erect. 1t happens not
unfrequently that animals are killed
by lightning under a tree to which they
had betaken themselves for shelter. In
these cases the tree is struck partly in
consequence of its isolation, and partly
on account of the presence OF the animals
beneath it. Usually there are several,
and often many of them assembled to-
gether, huddled probably by terror into
contact one with another. The air,
heated by their bodies, rises above them
laden with moisture derived mainly
from their breath. Who has not noticed
the cloud of vapor that in the early
morning and IN certain states of the
weather hangs over flock of sheep or a
herd of kline? The column of moist air
ascending through the branches of the
tree toward the cloud, offers, in conse-
quence Of the comparative high conduc-
tlyity of water, a favorable passage for
the electricity. A herd of cattle under
an isolated tree is thus exposed to a
double risk; also it is evident that these
animals are in the open country less Sc
cure from injury than human beings,
who cannoe affect the atmosphere in a
like degree Chambers Journal.