The sun. [volume] (New York [N.Y.]) 1833-1916, 1914-06-12
Solar Observation on August 81
to Be Watched i'm Russia
by Americans.
TO PHOTOGRAPH CORONA
California Expedition Starts To-
day with Lick Observatory's
Director in Charge.
n, ". w. CAMPBELL.
Director Of Lick Observatory,


e,N Joss. Cal, June 1.-THE Crocker
eclipse expedition OF the University of
California will start from here tomorrow
N i's long journey to Kicv Russia, for
the purpose of witnessing the total eclipse
OF the sun which will he observed In the
vicinity OF Kiev on August FL
The expedition has been made possible
BY the generosity Of William H. Crocker
OF San Francisco, a regent of the Uni
versIty Of California. 1t will be in charge
Of Director W. W. Campbell Of Lick OBJ
servatory. and Heber ID. Curtis, astron-
oner OF that observatory, will be his as
ISOLATE
So far as liz known at present no other
expedition will go from North America,
and but one from South America--that
from the University OF Argentina
The eclipse occurs in the afternoon
Tho moon. passing between the sun and
the earth will cast shadow upon the
earth some eighty miles in diameter
which will advance continuously across
the hemisphere of the earth turned toward
the sun.
The shadow path will begin at sun
rise in the Arctic Ocean. just off the
northern coast line OF British Columbia. in
longitude l2l degrees. IL will pass east
erly across Greenland and thence south
easterly over Norway. Sweden. Russia,
the Black Sea and Persia. ending at sun
set in northwestern India.
The Solar Corona.
The purpose of all eclipse expeditions
which cannot BE observed except IN times
Of total eclipse. and likewise certain other
phenomena of the suns surroundings
which demand a darkened sky. Interest
always centres In the solar corona. n
magnificent structure extending outwardly
IN all directions from the spherical body
which the earth sees every clear day.
many of the streamers having length
Of three or four times the diameter OF
the sun.
Several astronomers have tried to solve
the problem Of securing coronal observa-
tons without eclipses. but they have failed
totally, and the future gives mo promise
Of success. The Croker expedition, a
clear sky permitting. will secure photo.
graphs OF the corona on large scale
with a camera forty feet in focal length
and on a small scale with camera OF
seventy inches focus.
Other photographs of the corona will
b, made by means OF special apparatus
specially designed to test the quantity Of
the light proceeding from the coronal
structure. whether this light proceeds
from tnCandescf mt materials in the
corona or whether II originates in the
sun itself and is reflected or diffracted
TO Us by comparatively cold gases or con-
crete particles forming the corona.
The spectrum of the corona and OF the
higher strata In the suns atmosphere
viii be studied by means Of five specto-
graphs.
II need hardly be said that the purpose
Of the observations described is TO de-
tsrmine the chemical composition of the
corona and Of the outer strata OF the
SUMS atmosphere and the physical con-
ditions existing therein.
The Theory of Light.
In view Of the extensive experience OF
the Lick Observatory in eclipse observa-
ION and before 1t was decided that an
expedition would be despa tched to Russia
tho observatory of the University OF Der.
l0 requested Director Campbell to MAKE
certain obSirvatlons at the time of the
Russian eclipse in order to test an i'm
portant point in "A prominent modern the
DRY OF light.
In accordance with this theory II the
rays o. light from "A star or other source
pass close to the sun or other strongly
attracting body these rays Of light should
be bent from their straight paths by the
SraNtational action OF the disturbing
body.
Complying with the request of the Ber-
I'm observatory tho Crocker exps ditto =
VIII attempt to secure photographs OF the
stars In tn" region OF the sky occupied by
bat .a.l.E
from us than the SUM by means OF four
cam ras of eleven feet focus
These instruments. mounted here at the
obs rvatory, have already secured photo
graphs Of the stars In the region OF sky
which the sun will occupy on August 81.
me photographs OF the same stars with
no eol!psed sun in their midst which Il
i hoped to secure I'm Russia. will be
compared with the photographs at Mount
Hamilton.
II the angular distances between the
lwo sets of photographs are unchanged by
NE action of the suns gravltation the
theory of light referred to will be thrown
INTO very serious doubt. If the angular
distances are changed az the theory de-
mands the result will be OF surprising
interest to physicists as well as to astron-
Omers
II Is scarcely necessary to say that an
eclipse expedition is not n pleasure trip
-" ''lllN' ~ uuc 10 OCCUR at IL certain
period In the present case II will last
ror two minutes and fourteen seconds
The dozen instruments must be so care
ally mounted and adjusted during the
preceding month and the fifteen assistants
,''' o." go thoroughly trained to Their
du'iss IN the preceding week that each
Instrument and each observer will accom-
push mt given seconds through totally
what the programme demands.
--------rr-