New-York tribune., 1907-04-21
LIGHTNING PROTECTION.
Careful Study Of Problems InrOLred
Pursued at Washington.

AgSAGH III w uSu&H2 IOWs
Washington April 2O-In one OF the labo
ratories of the George Washington University
in this city stand the models from which new
system of protection from lightning has just
been adapted fer all the buildings and Chin
neys in the various yards Of the United States
navy Perhaps no better place for playing with
lightning after the sober. serious scientific fash
ion exists anywhere. Typical among the models
is a miniature brick chimney about two feet
high and four inches in diameter bearing four
little metal rods whose most noticeable pecul-
iarity is that they not insulated from the
chimney by any of the ordinary glass devices.
but are SO constructed as to allow whatever
electricity is induced the broad surface of
the chimney to drain of. instead of remaining
there TO disintegrate the brickwork should
disruptige discharge occur.
A copper spider spread across the top of
the chimney radiating network Of wires.
connected with the vertical rods-is another
special feature. Down the interior Of this toy
shaft. and the applies to the big. real
stacks of industrial centres no chance is Of
fered the bolt from overhead TO pursue its way
dealing death and destruction in the engine and
boiler rooms about the base.
That's a vital consideration. also. When
chimney is daily pouring heavenward col
Umn Of smoke and other products OF combus-
tion including not little water yapor. which
always accompanies combustion of fuel, there is
likelihood that in some thunderstorm a swift dis
charge from above may send alternating cur
rent Of incredibly swift vibration down the long
bore Of the shaft Many valuable stack. sup
posed TO be protected from the electrical hazard
by a system Of exterior rods, has been badly
damaged through the failure of its builder to
appreciate that a gaseous conductor reaches
much higher and is often better conductor
than the rods, and may therefore serve as the
chief channel along which the opposing electrici-
ties Of sky and earth rush to meet each other.
on the model in the George Washington Uni
versity, IL the feet OF the spider are firmly at
tached to the ends OF the vertical conductors.
the descending discharge when it reaches the
copper network will be sent harmlessly TO earth
outside the stack
Testing this and other schemes OF protection.
DR. n. Monroe Hopkins, assistant professor Of
chemistry ia the university and electrical engi-
near OF the United States navy. is able at any
time to produce a miniature thunderstorm, one
Offering just such conditions those in the
midst Of which the tail stacks OF Uncle Sam
navy Yards in many cities need TO be protected
from the assaults Of Jupiter PluVius No down.
fan Of rain or hal. TO be sure. accompanies the
electrical display in the bare little laboratory,
where with meagre and generally homemade ap-
paratus scores Of experiments important to
human progress have been conducted; but the
play Of lightning is as real and 70 the visitor
almost as aWe-inspiring as in nature BY means
of a tandem OF ''step-up transformers" the in
vestigatOr sends cracking across the air from
his electrodes 10 his lightning rods a current
which, in the language Of the electrician. is said
20 be under pressure Of 100000 volts, or as
the ordinary man sees il. sharp enough 20 make
him blink and wonder if he is going to escape
Ike he ligh IN clouds
whose voltage is so great that it can hardly be
measured this is an alternating current with
which Dr. Hopkins reprOduces the effect Of th'
terrifying flashes Of summer thunderstorms
How swift the alterations is featured in The
statement that they reach as high as 2oO.ooo
second. They can be measured. too. by use oi
r.aecfion devices familiar to physicists and cleo
tricians Indeed DR.. Hopkins. working In thi
laboratory some time ago achieved the feaS o