The times. [volume] (Richmond, Va.) 1890-1903, 1891-08-07
The Bes. Way to Ward on Lightning.

Professor Henry A Rowland. OF the JOHNS
Hopkins University. in an interview recently
gave some interesting facts in the develop
ment of the study of lightning and lightning
conductors. Dr. Rowland said: Recent
scientific study has swept away some OF tho
old notions about conductors. The method
now considered the best for the projection y
buildings is 10 provide metal roof. with al
ample number # metal conductors leading %
tho ground, which will receive and carry off
the electric bolts from the clouds. Copper IL
the best material, but tin u iron will answer
the purpose, and always suggest the placing
of the conductors at the corners Of building.
so that all parts will be eqtally protected.
Though rods may be used. rain spouts
will answer the purpose equally well. The
physical laboratory of the Johns hopkins
University is protected from lightning by
the roof and spouting. You can safely class
all patented lightning rods rs being OF little
value beyond conducting rods that any man
can put up himself. because the simple prin-
ciple underlying all is that the lightning will
follow the best conductor. The idea so
largely adopted in the erection OF lightning
rods. that small band Of glass will prevent
the electric current from passing 70 better
adjacent conductor, seems playful. While II
is true that lightning is attracted 70 an ele-
waited point or angle when you cast your
eyes over city like Baltimore and see tho
largo number of such points and angles. tho
use of pointed rods fades into insignificance
as compared with the method of roofing with
a good conductor. This was well illustrated
by the incident of lightning striking tho
great monument in Washington several
years ago. The monument is capped with
piece of aluminium. which has metallic con-
nection with the ground by means OF the iron
work of the interior, but the lightning did
not strike tho top of the cap. II descended 10
some corner fixed in the side Of the pyramidal
top. some distance from the apex burst pOr-
ton Of the stone and, running along tho cop
per into the interior leaped without any me-
talic connection to the iron framework and
passed to the ground, framework OF cop
per rods covering the angles and crossing
the sides of the immense capwas recommend
ed by me at that time for tho future protec-
ton of tho monument. and has probably been
constructed. The ground connection was 10
be through the internal iron work spoken OF.
Somewhat similar 70 these methods Is that OF
the Peabody Library. The iron shelving con-
nected with the metallic roof, and resting on
a stone foundation which might be- shattered
by a stroke of lightning. has been connected
with the ground by metal conductors, and no
danger from lightning is apprehended.
Lightning has no fixed portion of build
ing To strike. The stroke may fall at tho CEN
ire Of a roof and while 10 runs along the sur
face of body. the body may be broken or
crushed by the enormous pressure brought
TO bear upon 1t, in the same manner thal an
explosion of dynamite or nItro-glycerlhe
would cause fracture. | have some rag
ments of q church spire struck by lightning
which are bound together in their former
relative positions, but exhibiting all the trac-
lures produced by the conclusion. There is
a vast difference between the quantity OF cleo
tricitv and what il known rs electrical pres
sure. This is illustrated in a simple manner
bv the compression of mir A small quantity
of air can be compressed 10 the same degree
TO obtain as great an expansive force as large
quantity The quantity of electricity IN a
stroke of lightning IL not nearly as much
as passes along almost any electric wire Oh
the street. but the voltage OF electrical press
ure of the street wire is rarely 5000. volt ~
the basis on which the pressure Is estimated
The voltage Of the lightning stroke Is roughly
estimated at 5000, 90 volts. In addition
10 this appalling difference 1t may be SAID that
the current Of the wire IS constant and con-
tlnuing. while the lightning dart Is delivered
in the one two-hundredth part 4 second.
Such an astonishing force IS capable OF doing
many strange things. A volt may he rated as
equivalent to the pressure Ofan electrical door
bell"
In speaking Of places Of safety during nm
electrical storm DR.. Rowland said that prob
ably as safe place as any other woul1 DO an
iron bedstead. provided the ground connec-
ton is perfect this being in line with the
above theory. that the lightning would follow
the best conductor. Baltimore Sun.