The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1901-08-25
ABOUT LIGHTNING.
Popular misconceptions Concerning
Its and Nature.

Electrical Review.
Without doubt lightning was the first
electrical phenomenon that was ever OBJ
served by human beings. To this day it
remains the least known and least under
stood OF natural electrical manifestations,
except, perhaps, the aurora.
There is a vast deal OF popular miscon-
ception concerning the danger of lightning
and the nature Of it. The lightning flash
Is a discharge from a cloud at a high po-
tential with reference 10 the earth. When
the atmosphere is charged with water va
por ana some eddy or current In its colder
upper strata is DETECTED downward, caus-
ing condensation, exceedingly minute drops
OF water are formed, each bearing an cleo
into larger drops results in a very great
increment or the potential of the charge,
since the capacity OF the drop varies with
It's diameter and the volume of the drop
with the cube of the diameter.
The consequence of this is that IL takes,
for example. eight drops consolidated to
make one OF twice the diameter of the
constituent drops, and the charge on the
surface or the consolidated drop will be
four times as great as that upon the sur
face or its elements. In this way, as the
small water particles unite to form drops
which fall as rain, the potential Of the
charge they carry increases until it. at
tains enormous values and the lightning
nasn leapS 10 the earth, which may De re-
garded simply as a body OF very great
oAt1NA oNdll capacity. MS loOild -
which is called lightning, is apt to be more
or less destructive, although the energy OF
an individual flash is perhaps not very
great.
Often the conditions are such that the
discharge takes on an ~oscillating charac-
ter, producing violent surgings OF current.
No very accurate measurements have been
made upon the currents involved. but IT is
taken 10 be of the order or 1000 TO 5000
amperes. The electro-motive force neces-
Sary TO cause a flash a mile long Is prob
ably several million volts, and, or course,
the power OF the flash measured in watts
is very great, but its duration is CORE
spondingly short.
Protection of property and life from
lightning flashes has been. a subject that
has ~entrained the attention of natural
philosophers since Franklin sent up his
historic kite. The net result of more than
a century of attempt to secure protection
has been the lightning rod, In Its more or
that buildings of modern construction hav-
ing metallic roofs, and often metallic
frames as well, are practically immune
Der of deaths due TO lightning In any
given summer is comparatively very small
lin the ratio Of about one to each 100000
population in the United States.
In cities the destructive influence or llght
ming is exceeding small, although occa-
sional fires are cused by it, especially where
gaspipes abound. Protection Of electric cir
cults from lightning has been an interest
ing subject for research for a number OF
years. and several highly efficient devices
have been constructed for this purpose.
To-day lightning is little feared by the
station superintendent and should be very
little feared by any one. The time-hon-
ored rule that il is wisest to keep in the
open and not seek the shelter Of trees is
one which common prudence dictates. Re-
course to the feather bed OF our ancestors
however, is no longer necessary, except tC
quiet the nerves of timorous persons, while
the ancient superstitionS regarding han
ding steel instruments and sitting IN
draughts may be utterly disregarded. \
modern building in a city is as nearly alb
solutely lightning proof and those in it are
as nearly absolutely protected from light
ming as is possible.