Evening star., 1932-08-30

on both sides reflects light from soil
and vegetation into the darkened area.
For this reason it does not become
totally dark even in the area of total
ity. The effect is much greater in the
area of partial eclipse.
Dancing Crescent Effect.
One phenomenon which certainly can
be observed here is the dancing crescent
effect under tree with thick forage.
Images of the suns crescent will ap-
pear all over the ground, due to the
light from the narrow band of light
coming through the interstices of the
leaves. These interstices act some
what like the eye of a camera, pro-
ducing inverted images on the ground.
The effect can best be observed when
the eclipse is well under way.
Washington is just out of the area
where shadow bands are likely to ap-
pear, although there Is bare posi-
bility, If conditions are just right, that
some of these may be seen. They are
fieeting strips Of light and shade which
seem to dance across the ground. They
are shadows of layers in the atmosphere
of different temperatures, made visible
when the light comes from the slit
like crescent of the sun.
Although most Of the astronomical
observation is to be centered along the
path of totality. the Naval Observatory
has set up instruments here for one
important piece of work. The progress
Of the eclipse will be observed through
three different instruments, operating
simultaneously 12-inch and 5-inch
telescope and a photoheliograph.
Through the 5-inch telescope fixed
on the sun an observer will make a
visual observation of the exact mo-
ment the eclipse begins and rigidly
time observations Of various points in
its progress. The 12-inch telescope will
not be used for direct visual observa-
tions, but instead the image of the sun
will be projected through it, much en-
larged, upon screen. Two observers
will stand beside this screen. As soon
as the dark notch in the suns edge
becomes visible on the enlarged image
one will signal to the other, and simul-
taneouSly each will make dot, one at
each end Of the notch These stimuli
taneouS markings will be repeated from
moment to moment as the darkened
area grows larger. This will result in
a graphical representation of the prog
resS Of the eclipse. With the photo
heliograph series of photographs will
be taken, recording almost continu-
ously the progress of the eclipse.
Three Records to Be Made.
Thus the Naval Observatory will have
three carefully timed records of what
actually happens in the meridian of
Washington-one visual, one graphi-
cal and one photographic-wh can
be checked against each other and
against the predictions which have
been made months in advance.
The main Naval Observatory party
consisting of about 20 men, will be al
Limerick, Me. In the party will be six
astronomers and naval officers from
the observatory, together with a erouu
Of enlisted men, who will aid in the
setting up and operation of the instru-
ments.
The Georgetown University party Is
at Fryeburg, Me, in charge of DR.. Pau
A. McNally.
Another group of Washington OBJ
servers. sent out by Science Service, will
make photographs of the progress OF
the eclipse from the summit of Mount
Washington, highest point in the path
of totality, which has been passed over
by other institutions because of the
hazard Of bad weather.
| WEATHER MAY RE FATR