Jury 12, 1918] 
with cameras of focal lengths from eleven 
inches up to forty feet, have been developed, 
and the details of coronal structure were re- 
corded with admirable sharpness, showing that 
the instruments were in good adjustment, and, 
what is equally important, that the earth’s 
atmosphere traversed by the coronal radiations 
was in a tranquil state. 
TEST OF THE EINSTEIN THEORY. 
Four cameras of fifteen feet focus, using 
plates of 14 by 17 inches, recorded the brighter 
stars existing in the region immediately sur- 
rounding the sun, though vastly further away, 
with apparent success, but their examination 
and suitable study can not occur until many 
days after the plates reach home. It is hoped 
that the measured positions of the recorded 
stars will serve as a test of correctness or 
falsity of the so-called Einstein theory of rela- 
tivity, a subject which has occupied a foremost 
position in the speculations of physicists and 
others during the last decade. 
If Einstein’s hypothesis represents the truth, 
then the positions of the stars on the plates 
should be affected during the action of the 
sun’s grayitations upon the rays proceeding 
from the stars while the rays are passing 
closely by the sun on their way to the earth. 
The test as an eclipse problem has never been 
made before, and it may be the only satis- 
factory test known to physicists, but whether 
our work will contribute evidence of value re- 
mains to be seen. 
The same four plates should contribute 
something of value as to the existence or non- 
existence of any known bodies, such as the 
hypothetic planet Vulcan, in the vicinity of 
the sun. We expect to find no strange objects 
in the region commanded by the plates, and 
that the evidence will be wholly negative, but 
such comments have no weight a present. 
Two spectographs were successful in their 
purpose of recording images of the stratum of 
green coronium gas enveloping the sun. This 
stratum is relatively thick over the east and 
west areas of the solar surface, but thin over 
the polar regions. The distribution of coron- 
ium is very irregular. The accurate position 
SCIENCE 35 
of the green coronium line can be determined 
with good accuracy from the images obtained 
with a three-prism spectregraph. 
The general spectrum was recorded in good 
strength with two spectrographs. The evi- 
dences of polarized light are strong and defi- 
nite on photographs obtained with two po- 
larigraphs. Just what is the nature of the 
evidence which they will afford as to the com- 
position of the coronal streamers will depend 
upon quantitative measures demanding time 
and discussion. 
Four photographs were obtained by Miss 
Glancy, assistant in the National Observatory 
of the Argentine Republic, for that institu- 
tion, to serve as a basis for determining the 
total quantity of light radiated by the coronal 
structure. She has taken the plates with her 
for later development and study. It is possible 
that her results will be affected unfavorably by 
the clouds which extended close up to the 
coronal structure, and it is possible that some 
of our Einstein and Vulcan plates are simi- 
larly damaged. 
We constantly revert in thought and speech 
to the remarkable coincidence which brought 
a very small rift in the clouds, the only rift 
visible in the entire sky centrally over the sun 
and corona during the three minutes—and the 
three minutes alone—which interested us. 
The expedition was composed of Director and 
Mrs. Campbell, Astronomer H. D. Curtis, As- 
sistant Astronomer and Mrs. J. E. Moore, and 
Foreman J. E. Hoover, of Lick Observatory; 
Professor E. P. Lewis, of the Department of 
Physics, University of California; Mr. A. H. 
Babeock, consulting electrical engineer of the 
Southern Pacific Co., San Francisco; Miss 
Leah B. Allen, instructor in Wellesley College; 
Miss Estelle Glancy, of the National Observa- 
tory at Cordoba, Argentina; Professor S. L. 
Boothroyd, University of Washington; Dr. 
Ambrose Swasey, of the Warner & Swasey Co., 
Cleveland; Dr. John A. Brashear, Allegheny, 
Pennsylvania; Professor Douglas Campbell, 
Stanford University; Dr. J. S. Plaskett, di- 
rector of the Dominion Observatory, Victoria, 
BG: W. W. CampsBe.n 
Lick OBSERVATORY 
