Elmore bulletin. [volume] (Rocky Bar, Idaho) 1889-1906, 1891-12-19


duotiag Currents--High Houses.
Now, as charge OF electricity has the
property OF inducing another charge of
electricity Of an opposite kind to itself ON
any conducting matter near 1t, and as
the earth Is composed Of what is called
conducting matter, II follows that
charged cloud sailing over the surface OF
the earth induces an opposite charge on
the ground below. These two opposite
charges one OF positive" the other of
negative electricity, tend. by another
well known property of electricity, to rush
toward each other and combine. Hence
when they are able 10 overcome the resist
ance of the air between, which keeps
them apart, they leap together with fash
and crack, producing the familiar phe-
nonena 1T thunder and Lightning
Sometimes another cloud floating near
the first one takes the place OF the earth,
aud then the lightning dash takes place
between them. Lightning Of this kind
does not strike the earth; but IL might
have a destructive effect on the latter for
all that, because It might give rise To the
hack stroke" which Ii sometimes fatal
To life. The back stroke" Is not due TO
the direct fash and discharge. IL is
rather the reaction after the direct dis
charge has taken place elsewhere. Sup
Z
country, a rural district with trees farms,
and here and here church dotting IL, is
covered by u thunder cloud which induces
a charge of electricity upon IL. In order
that the charge upon the earth may get
nearer TO that upon the cloud, 30 as to
combine with II, the electricity, by another
well known property, will heap itself on
the most prominent and pointed objects OF
the landscape That is TO say, IL will ac-
cumulate on the trees, barns, chimney
tops aud spires of the district.
The whole atmosphere Ut tho region In
IN a state ef tension and suspense. The
bolt il trembling IN the balance, but 70
man knows where ii will fall, Presently
there is binding flash OF light, the sky
l. rent with lurid stream of fire, and in
stnntly the tension II relieved. The dis.
charge has taken place at one point, the
point which offers the puth of least resist
ance through the air, and at which the
electric tension was most critical. At
every other place where the electricity
hal seriously accumulated, there is con-
sequently a sudden fall Of electric poten-
tial, or n collapse To its old condition, or,
as il is called, "A return stroke" This
instantaneous change is sometimes as
fatal n the direct discharge, and IL may
ruin a building or destroy life several
return stroke IL therefore more mysterious
and unexpected than the Hash. but fatal
effects are comparatively rare from 1t,
Nevertheless since the latter have been
attributed Ia this cause, person cannot
feel quite safe, although II thunder storm
with lightning is still several miles from
him; the number III miles heing estimated
by counting the seconds which elapse be-
, tween the flash aud the peal, and allow
ing distance of four miles for every
second counted. lie may feel safer than
II IT were cluse upon hiin, but there Is still
some room for fear.
In fact there Is no real safety except
within the aren properly protected by a
: lightning conductor, or In building
| which Ii itself protector, for instance a
! sheet iron house. Every building, then,
should be protected in order to be safe
: In the country, where these are often
isolated, a lightning rod would be required
D for each: but in towns one rod would
r sometimes project more than one house
I around 1t, according To its height and CON
ductiyity.
The flash takes place at the point oi
least resistance, because IL is here that the
: two opposite electrieities can easiest rush
a together. But the cagerness with which
: they tend To rush together is another
thing to be considered. These two thing,
4 taken together determine the discharge
There may be less resistance To the fiast
q al one house or tree than at another, bu
4 IL the attraction between the opposite
: electricities IL less at the former, the ilasl
1 may traverse the latter house. Hence
4 one cannot exactly say If one tree o.
a building will be safer than another. Their
Il Ii great uncertainty, and this is reasol
for the instinct of awe and uneasines
| which most animals feel ON the approach
Il OF thunder storm.
4 In general, however, we can say tina
!. high houses. or those perched on higi
: ground, are more likely IA suffer from tn
"a discharge than small low Lying houses
: The former are therefore all the more eli
a gihle for projections; and they are to b
= avoided in seeking shelter from storm
y So are houses surrounded 10y trees, an
!. with ponds or pools OF water close besid
= them. For trees act rs imperfect lighi
= ming rods, having n good earth connection
5 and especially II they are wet the di,
!. charge may strike the house in order
!. reach the ground through them, or, In I'll
= case Of the pond, through the water. On
: should not shelter under trees OF an
: kind but more especially tall. soft tres
!, like poplars. Many deaths have been IL
Il CURED from sheltering under poplar tres
= In France
Thunder storms are said to be MOI
frequent in open, treeless countries, sue
as the Transyaal or the Scottish hills, an
q the fact has been attributed to the III
M checked ascent Of electrical yapors; bI
4 ON the other hand they are probably les
m destructive In such countries.
) Ghimneys, by creating currents Of war
smoke and by their lining Of coaductin
SCOT, are dangerous parts OF houses, an
there are many instances of the diseharl
taking that road. II were better, then,
avoid sitting near a fire in storm. Il
deed, the safest place in the house on sue
an occasion would seem to be in the eellr
and basement rooms or upon an iron bes
stead. In the open air there cannot be
safer place than dry hole or ditch, for
places the body below the surface of II
ground, and therefore not exposed on
prominent place Bni IL should be a DIR
hollow, else the wafer IN il may invite Oh
discharge; for water being a conductor
good connection with the earth, lower
the resistance 10 the discharge. .-Engineel
ing.