Evening star., 1932-07-28
SCIENCE TO PROBE
ECLIPSE OF SUN
Instruments From West
Coast Brought to New
Hampshire for Study.
BY THOMAS r. HENRY.

The suns corona, the luminous
crown which surrounds the blackened
disk during a total eclipse, will be the
special object of study OF the Carnegie
Institution of Washington expedition
to the New England eclipse, August 81.
Special apparatus now is being
brought across the Continent from the
institutions observatory at Mount Will
son. Calf 1t will be set up on a
mountaintop near Lancaster, N. II.
This site, of slightly more than 1000
feet elevation, was selected after
careful study of sites where weather
conditions will probably be most ia
vorable. :.
The study of the corona will be d.
vided into three main projectS-study
of the gaseous atmosphere Of the sun
by means of the flash" spectrum;
spectroscopic analysis of the light OF
the corona and measurement OF us
heating effect. Apparatus for each OF
these projects has been especially de-
signed and constructed for this rare
occasion by the Carnegie astronomers.
Bv this means it is expected to make
observations which never before have
been possible. Considerably mystery
still attaches to this strange phenome-
non of the moment of darkness when
the shadow of the moon passes across
the lace Oh Itlc sun.
Described as Beautiful
This luminous crown around the
disk of the moon sheds pale, green
ish light, about half as brilliant as tne
light of the full moon. Usually there
are several long streamers OF light eX-
tending into space distance OF sew
eraI times the suns diameter. FROM
the poles there may emerge a series
of brushlike rays of light. Close 10
the moons disk emerge req sonar
prominences, huge flames OF hyorosen
and other gases.
one of the most beautiful objects ever
heheld by man. 1t lasts less tnan TWO
minutes. AS the sun begins to emerge
from the moons disk the effect mas
been described as that OF vast ola-
mond ring suspended in the SKY, the
slender greeniSh corona forming tne
band and the reappearing sun the
By means of the flash spectrum" 1t
is hoped to secure further data on the
actual chemical composition OF tnis
luminous crown. There Is some eVlI
dence that it contains a hypothetical
element coronium. which never has
heen found on earth. Some MAINTAIN,
however. that the curious spectrum ef-
feet is due to some well known element
in form in which it never Is expert
enced on earth.
The flash spectrum, according to the
announcement of the Carnegie InStl-
tuition plans, will be photographed on
a moving film with the aid OF a flve-
foot defraction grating Of five feet
focus Two other concave gratings, OF
six feet and two feet focus, respectively;
will record the ultraviolet, the visual
and the infra-red parts OF the coronal
spectrum. a special spectograph Tor
observing the spectrum of any promi-
nences that may be visible at the time
of the eclipse also will be part OF the
eouipment. All these instruments VII!
be fixed on the ground and supplied
with light from the eclipsed sun by
mirrors moved by clockwork to keep
pace with the eclipse progress.
Radiation to be Measured.
Some of the most delicate observa-
tions will be made in measuring the
heating effect of the corona. the
astronomers will use rejecting tele-
soope which will concentrate radiation
from the corona on sensitive thermo-
ccuple, an instrument so delicate that
with it have been measured the tenn
peratures of restricted areas of dis
tant planets. The response OF the
thermo-couple to the resultant rise In
temperature will be recorded auto
matically on moving Photographic
plate by means of galvanometer. An
automatic device will shift the re-
ceivers of the thermo- couple alternately
from one side of the corona to the
other.
The total radiation of the celestial
ring will be measured and, in addition,
the radiation transmitted by glass and
by a cell full of water. Comparison
of the three results will indicate how
the radiant energy received from the
corona is distributed through the solar
spectrum. That which is due TO the
ultraviolet part of the spectrum, Tor
instance, will not pass through the
glass.
The expedition will be in charge OF
DR. Walter S. Adams of the Carnegie
staff who will operate the fash spec
trum apparatus. The coronal spec
trum will be photographed by Harold
son and Edison Petit will observe with
the 20-inch rejecting telescope.
DR. Theodore Dunham OF the Mount
Wilson Observatory and DR.. Fred E.
| Wright of the Geophysical Laboratory
here will Join the party shortly before
the eclipse and carry out special IN.
vestigations The results obtained Will
! be subjected to intensive mathematical
treatment following the eclipse.