Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1895-07-06
COMMUNICATED.

| In 1891 the weather bureau Sued In
structions t, IFS observers loclte at
various points to report at the end of
each month the number of persons, ii
any, injured or killed by lightning in
their vicinity. This information b: 9
been carefully tabulated and shows that
in the LIST four years the number Of
deaths from this capse have averaged
1876 per annum.
Not considering the thousands of dol
lars of damage done to property an
nually by this agency the figures given
show that the subject of protection
against lightning is very important
one.
The "Leyden jar" piece of expert
mental apparatus familiar to every per-
son who has ever studied physics, full
fills all the requirements for the produc-
ton of miniature lightning. 1t is simply
a glass bottle covered inside and out
| with tin foil for holding or condensing
an electric charge. This is what Frank
lin used in his famous expeliment of
drawing electricity lfom the clouds,
and gave rise to the popular expression
"bottled lightning" When the charge
upon one of these jars exceeds certain
definite degree of intensity disruptive
discharge takes place between the
plates of tin foil. This is precisely what
occurs during thunder storm, a dis
ruptive discharge between two op-
positely electrified clouds or between
cloud and the earth.
The intense heat produced by the
passage of the electric fish expands
the surrounding atmosphere to an ex.
tent equal almost to vacuum, and the
rush of air ct normal temc"cature, to
fill this vacancy, produces the thunder
which always follows. IS the velocity
of light is instantaneous compared with
that of sound, the distance of storm
can be easily estimated by remember
ing that sound waves travel only at
about the rate of l 100 feet per minute.
Notwithstanding the many argu-
ments to the contrary, Franklin proved
beyond doubt the efficacy of lightning
conductors. Statistics show, and it
should be expected, that the danger
from lightning is several times greater
In the country than in cities. Barns
and stables are the structures most ffe-
quently damaged, while unprotected
churchspires offer unusual inuucement
for the lightning's stroke. McAdie
SAYS: "For ordinary dwelling houses,
not unduly exposed, in city blocks,
lightning rods are hardly nee ssary, a
very considerable protection being af-
forded by tin roofing, cornices, cutters,
Q~o
that all metallic work on building ts
connected with the ground. Lightning
rods should be made of iron or copper,
preferably the latter. One end should
be buried in the ground to such depth
that it will always be surrounded by
moisture and should terminate in
good sized metallic plate.
The top of the rod should be pointed
and tipped with some non-corroding
metal such as aluminium. Rods should
be examined every spring, and any
breaks in their continuity should be
Immediately repaired; this is especially
liable to occur in case of copper where
it enters the ground. Nearly all au-
thorities upon this subject up to within
very recent times assumed that light
ming always followed the path of least
resistance. 1t is simply hopeless to
pretend to be able" says Lodge, "to
make the lightning conductor so much
the easier path that all others are out
of question. The path will depend large
ly upon the character of the flesh" !"
Proximity to trees or live stock should
be avoided during thunder storm, and
it is not advisable to stand in doorways
or near chjmneys. There is nothing to
be gained by hiding in darkened rooms
or between feather beds.
The action of electricity upon the
human body, whether it be in the form
of lightning or otherwise, is little under
stood, and many cases of resuscitation
are or record where the victim has been
pronounced dead. The writer knows
OF several cases of suspended animation
produced by lightning shock and he
advises artificial respiration unceasing-
| ly for from one to two hours.
CHAs. f. THOMPSON.
Alexandria, Va.
| -0