The Savannah morning news., 1900-06-10
Fig. I.

sembling in its arrangement a photo
grapher's "foor-ground." This nearly
horizontal extension was designed TO show
the motion of the bands az a considerable
angle, as compared with the upright
screen. Both parts of the screen display
ed prominent marks, indicating dimen-
sions in oil directions to facilitate meas
uring both ocular and Photographic re-
suits
The shadow-bands appeared as distinct
ly contrasting but elusively outlined and
vaguely splndle-shaped markings arrayed
in seemingly straight ranks, which ranks
moved rapidly in a direction at right an
giles to their length, marching across the
upright screen from above and from the
left of the observer. standing with bis
back to the eclipsed sun. In other words,
they moved diagonally downward and
northward The long axis of each spin
dle-shaped ripple-shaped marking
pointed roughly toward the North
star. Each ripple appeared to
be from one to perhaps three
feet long and from one TO three
or possibly four inches across. In, color
they resembled lighter and darker Shades
OF smoke, showing absolutely no trace Ct
color only the varying tints CT a mono
chrome gray. They chased each other
across The screen-like wind-ripples flowing
over large flag. Their vagueness of out
line together with the neutral color AMI
rapid flowing motion, to say nothing of
the mental tension Of the observer, M de
any more accurate estimation Of their ex-
act size quite out of the question. Owing
10 the necessarily rapid handling of the
camera no opportunity occurred for the
writer to note the appearances on the hori-
zontal sheet.
Providentially the behavior of the bands
on horizontal surface was noted by
POmDptenf witness and scientifically
trained observer in the person of Capt.
CaSsius E. Gillette, L. 5. A, Engiuver
Corps, who detailed his observations 10
the writer within seventeen hours after
the eclipse. While walking due east along
a road directly below the hill wheieon
was located the observation station, he
noticed the shadow bands. Turning about
SO as TO face the wesI Capt. Gillette saw
the bands apparently coming down the
road from west 10 east, but moving In a
line at an angle of about 45 degrees with
their length! This appearance was evident
~ caused by the invisibility of the lines
on either side of the road where the grass,
bushes, etc, furnished no such screen as
did the light colored dusty highway; hence
the bands tho actually moving diagonaly
ctJsswlse from southwest to northeast,
produced the Elusive effect of sliding
down the narrow stretch of road with an
obrque front
Now, inasmuch as the suns rays did
not fall perpendicularly upon either the
upright, or nearly upright screen, nor upon
the ground, but rather into the angle be-
tween surfaces so placed, we see at once
that the apparent motion downward and
northward on the eastern aspect OF the
screen and the apparent motion from
southwt st TO northeast on the ground are
both the outcome OF true progression or
the bands in a direction identical with
the moons motion across the sun: or more
t. Lar
later on, in the line of perpendicular
drawn to a tangent on that arc OF the
Gmbra passing over our particular sta
Il u.
II is wen known that hitherto the sha-
dow-bands have batfied solution; more
than that, they have at times been
Inscribed 10 optical Illusion and even had
their existence doubted. The latter verdict
Is satisfactorily set aside by the many
and positively stated reports OF their ans
pearance at numerous stations during the
eclipse OF May Is. Concerning the part
played by optical illusion the writer will
have word to say later on.
Pondering the curious phenomena ] had
witnessed, ] began 10 form some idea of
their probable cause while journeyng
home 10 Savannah the night on May 2s.
The irregularities upon the moons appar-
ent circumference aroused the question
whether or not the last attenuated cres-
GEM Of the suns visible surface might
not be subject to a series of irregularly
occurring, unequal. and sudden shorten
ines such might produce. instead OF
a uniformly gradual darkening. a series
OF sharply distinguished shades, II was
crude, unsciensifs theory, but to the
suggestions that II contained owe what
ultimately led to a clearer understand
ing OF the phenomena under considera-
ton. ] became aware of the need of IL
careful analysis OF the component light
and shadow elements that go to form that
enormous cone Of graduated darkness we
know as the penumbra. Again, ] realized
that only mental confusion could resu
20 long as the element OF time remained
In the problem. IL bands of light and
shade rushed over the earth's surface i'm
nediately in advance OF and succeedins
the black circle OF the umbra. why not