Evening star. [volume] (Washington, D.C.) 1854-1972, 1911-05-14
Astronomical Discovery by Smithsonian

time the mule was killed. but the delicsts
instrument reached the top in safety"
On this second trip the results were
highly satisfactory, and the tests at the
three points checked each other COM
pletely. Still this was not held to dem
onstrate nnally the correctness OF the
Abbot theory. 1t was deemed necessary
to make one more test with one station
so far removed from the others that 1t
would be out of the question for the
same local atmospheric conditions to exist
at both observing points. The cloudless
region of southern Mexico was selected
as being most favorable for this purpose.
Before asking Congress for the neces-
sary appropriation, however. Secretary
Charles d. Walcott OF the Smithsonian
Institution wrote to the leading astrono-
mers Of America and Europe asking their
opinion. Without exception they answered
that IL the measurements made in south
ern Mexico Tailed with those made at
Mt. Wilson simultaneously, 1t would be
proof positive of Mr.. Abbot's theory. At
the same time these scientists took oc-
casion to express their high admiration
for the work which Mr.. Abbot is doing.
many speaking Of him particularly as q
worthy successor to the lamented Lang
ley.
Accordingly Congress was asked TO in
crease the appropriation for the astro-
physical observatory in order TO make 1t
possible to send an expedition to the
granted, and now nothing stands in tire
way Of reaching final conclusion In the
Investigation.
Next month Mr. Abbot will leave wash
ington for Mount Wilson. and from there
he will set out for Mexico some time In
July, taking with him the same apparatus
that was used last year on Mount WHIT
ney.
During all the years that those inveeti
cations were being made, Mr. Abbot aeo
was working to improve the pyrhei-
ometer. the instrument used in the work,
until finally he conceived a new idea Tor
II which he began to develop Three sue
cessive instruments, all supposedly ms
were constructed. until in 1910 he had per
fected 1t to a point where an absolute
scale Of measurement could be fixed, Tor
careful comparison OF two OF these I'M
proved pyrheliometers showed they agreed
perfectly
In speaking Of his work and what he
hopes 70 accomplish, Mr.. Abbot says:
1.-THE measurements we have made
show on their face . range in the solar
radiation outside Of our atmosphere of
about per cent. Now the question is
is this variation real. or is it brought
about by inaccuracies OF observation, or
by some error in determining the losses
experienced in the air?
Now II the measurements were mac
curate and the range of variation were
due to that we would expect the meas
urements Of successive days to vary ir-
regularly. but. as a matter OF fact. the
successive days Of observation show a
regular march from the higher to the
lower and back again, showing that II
is not a mere accidental 1uctuation or
but something either In the
air or In the sun that Ii causing It. As
we have measured simultaneously in
on Mount Wilson and on
Mount whitney, without q difference In
the results outside the atmosphere, ft
does not appear that the variations found
on different days are caused by faulty
estimates Of the losses In the air; they
seem rather to be true variations Ia the
sun.
ssBy taking measurements in southern
Mexico and at Mount Wilson. which are
80 far apart that nothing common in the
can exist between them-tnat
IL. no common huctuation due to local
atmospheric dlsturbances-we may acti-
ally prove whether or not these varia-
tons are IN the sun or are something
we have not eliminated IN the atmos-
phere. II we ind the variations are n
the sun itself we shall have maAo =
discovery OF the first rank"