Alma record. (Alma, Mich.) 1878-1928, 1886-09-03
LIGHTNING STROKES.
A Theory I'm Relation 90 the Recent
Increase in the Number of Light
ming strokes.

ming strokes.
The researches of Prof. Won Pctzojd,
Karstcn Weber, and others have prov
ed that the number of damaging
strokes of lightning has considerably
increased during thc last fifty years,
and this increase can not be explained
by tho theory that. owing to the grow
ing number Of houses, factories. etc,
the number of lightning strokes in
creased proportionately; to the con-
trary, this number ought to decrease,
as every building. even when not pro-
tccted by lightning-rod, effects an
equilibrium of the opposite ele ctric
potentials, and therefore the number of
lightning strokes ought relatively to
decrease with the relative number of
buildings. This, indeed, is proved by
the fact that in the space of one year
among one hundred thousand buildings
there occurred but thirteen cases of
lightning strokes in cities, against
twenty-thrce strokes on buildings in
the country. We. therefore, have to
take this natural phenomenon from an
other point of view, and to consider the
ratio of damaging or other strokes TO
the number of buildings in a certain
district. This ratio, called by the Ger
man naturalists 6litzgefahr danger
from lightning), increased in the king
dom of Bavaria from 1914 to 1882 three
fold according to records of insurance
companies even iivefold), and other
countries show the same increase.
As in nature each phenomenon must
have its cause the question arises: To
what cause is due the aforementioned
facts? And this question not only is of
scientific interest, but also of great
practical Importance. A great many
theories have already been advanced to
explain this phenomenon; among others
that, owing to the decrease of the wood
land, houses are more and more made
the projecting points of certain area,
and therefore attract the lightning; be-
sides. this decrease effects a greater
rise in temperature in summer, and, in
consequence, more numerous thunder
storms. Others find the cause of it in
the large increase of such constructions
"a gas and water works, wcathcr-cocks,
etc. But this theory does not explain
why. especially country houses, which
commonly lack these kind of construc-
tons, are mostly exposed to danger
from lightning. Admitting that these
causes may 10 some extent explain the
increase OF danger from lightning they
are not sufficient to fully show the sur
prising increase of strokes during so
short period. There must be more
general and fundamental cause.
Through what can the electrical intens
ity during thunderstorm be so strong
ly increased that larger number of
lightning strokes pass over to the earth
than was the case heretofore? 1t is
not so much the increasing number of
thunderstorms rs their greater force
which produces the increased danger.
As the main cause we now point out
the enormous increase during the last
fifty years of factories, railroads. steam
boats-in short, of all constructions
filing the atmosphere with smoke,
vapors. particles of dust of every de-
scription. When we consider that
every day thousands of locomotives,
thousands of steamers 90 around the
earth; that thousands of factories of all
kinds daily emit enormous quantities of
smoke, vapor, and dust into the air;
that, especially in cities. the large num-
Der of houses produce immense quaint
ties Of smoke and dust. the assertion
will not seem incrcd BILE that there is
certainly one hundred times the smoke,
dust, and gases absorbed in the atmos-
phere that was fifty years ago. Al
ready with the naked eve the impure
state of the atmosphere may be noticed.
Go through the coal districts of Man
chester England, through those of
Pennsylvania, through the city of Pitts
burgh, and you will notice layer of
vapor constantly lowering over them;
the air is filled with foul gases, and
every object Is more or less covered
with the settling particles of dust
The cond tions being established, we
have to consider their relations TO the
violence of thunder-storms. To give the
reader a better conception of this rela-
ton we will briefly discuss the theory
of the thunderstorm ald the origin of
electricity thereby developed. Friction
is now generally accepted to b. the
cause of the electricity in a thunder.
storm. Friction between air and par
ticlcs of ice according to Lavine) or
between air and molecules of water (ac-
cording to Andries) is In, main cause
of that electricity. When besides these
factors particles of dust are filling the
atmosphere the development of cleo
tricity are highly increased. Ii is the