Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-06-22

photography ne intends TO make actual
mcdels Of lightning flashes. after first
calculating their lengths, diameters and
horse powers.
Mr. McAdie will be remembered as hav-
Ing several years ago made the first sue
cessfuf photographs of lightning and as
having revealed in this way many facts
concerning the real formations of flashes,
which the eye cannot observe. In the
meantime. by aid of the state weather
bureaus, he has been collecting data as
to distinctions and fatalities caused by
lightning. which he has published from
time to time in the bulletins of the ma
tional bureau. But this summers work.
he says, will be the most interesting of all
yet undertaken A great deal has been
learned concerning the effects of light
ming, but now more definite knowledge must
be had as to It's cause and condition.
Three large cameras are every night kept
focused upon the Washington monument.
This high structure, towering to the alti-
tude OF 800 feet, is looked upon as a tall
lightning rod in ITSELF Scarcely a season
goes by during which it Is not struck by
several OF Jove's unsparing thunderbolts.
Ten years ago it was attacked in this way
five times within twenty minutes. as a re-
suit OF which stone in the upper pyra-
midion was split. Since then, however, the
most complete system of rodding known
has been supplied.
The cameras in question are posted. one
on top of the weather bureau building
which instrument is attended to by Mr.
McAdie himself. one at the weather sta
ton IN the Capitol and the other at the
home OF an employee of the bureau, who
ives across the Potomac, a short dista ice
back OF Fort Myer, on the Virginia side
Each camera is kept continually focused
so that the negative will include a high
and broad expanse of sky in the same YER
teal plane with the monument. Telephone
communica ton is had between the points
and each observer Is under promise to be
on watch at his respective post whenever
In the night. thunder storm threatens to
PASS over the city.
Negatives of the Same Flash.
The views, of course, must be taken dur
ing the darkness, that the flash may be dis
tinctly seen. The watches of the three OBJ
servers are carefully compared each day,
and the exact time Of every exposure will
be noted to the second. In order that mega
tives of the same flash may be ident
The caps of the Cameras will be left off dur
ing each nocturnal storm, since the darkness
will prevent the destruction of the plates AS
soon as streak appears in the field Sc
lected the sudden flash itself makes an in
Simultaneous exposure. 1t will be arranged
that many amateur photographers in the
city may set their cameras for the same
purpose. since each additional view will
add to the completeness of the models when
made.
Having obtained views of the same flash
from the three or more points of observa-
ton, piece of wire will be held before
each photograph, and bent in accordance
with the lines there appearing. The lines
in each view will be bent in the wire, so as
to be included in the same plane, and in this
way the model will be an exact representa-
ton of the lightning itself when 1t passed
from one cloud to another. or to the earth
below, as the case may be.
Another interesting part of the expert
ments will be the calculation of the di-
mansions of the flashes. This. of course,
must be done before the model is made
All Of the measurements of the monument
are definitely known, to the fraction of an
inch, and since this high structure will be
visible in the photograph, 1t may be used
as a scale with which to measure the
length of the flash. Still more accurate
computations may be made by aid of the
transit, after finding supposed points in the
sky to correspond with the various ones in
the photograph. The distance between the
three observation points and the base of
the monument are definitely known, and the
various angles formed by straight lines
joining them, and others drawn to the
points in the sky. may be found by the in
strumentS.