Evening star., 1901-09-21
HEAT FROM THE STARS
MEASUREMENT OF WARMTH RE-
CEIvED FROM DISTANT SUNS.
Achievement Of English and Ameris
can Astrophysfcists-In
of Great Delicacy.
Erom the Philaaelnhi. Ledger.

From the Philadelphia Ledger.
AS IL 1t were not enough to have meas.
ured the enormous distances of those few
stars whose parallaxes are determined by
triangulation upon the only available base
line of the diameter of the earths orbit.
+ and later to have discovered by means OF
the spectroscope the general constitution OF
many suns, together with the rate and d.
rection Of their motion, astrophysicists pro-
pose to ascertain the quantity OF heat they
radiate to the earth across the immense
spatial abyss In this connection Profess
sor Ernest F. Nichols OF Dartmouth Col
lege has recently contributed new and
interesting chapter to the story of the
heavens.
So long ago as 1869 Sir William Hug
gins the eminent English physicist, at
tempted this particular investigation, and
published the results he thought he had
secured with his thermopile and galvan-
ometer. and the following year his conclu-
sions were practically corroborated by so
well equipped an investigator as DR.. h.
]. Stone; however. astronomers in general
were disposed to attribute the disturbances
of the extremely sensitive apparatus en-
ployed to extraneous and accidental
causes, and this suspicion apparently re-
ceived confirmation in the utter failure OF
Professor c. V. Boys of Oxford, in 1SSS-!O,
to observe the slightest indication of stel-
lar heat radiation with his iadiomicrometer
an instrument of such intrinsic sensitive
ness that without the aid Of concentrating
mirrors and lenses Is exhibited detection
of Comm. when a candle was placed at
distance of sixty inches, and when in con-
junction with a reflector of sixteen inches,
aperature. showed a detection of 3Smm.,
produced by the heat of a candle at a dis
tance of 80 yards, being fully capable or
detecting so minute degree or neat as
1-15O.OO0 of the amount radiated by the
full moon to the mirror
Heat From Arcturus.
Notwithstanding this circumstance, the
American electrical genius, Edison be-
lieved that with his micro-tasimeter he
succeeded In detecting heat waves coming
from the star Arcturus. but this now seems
quite improbable, because of the compare
lively small capacity of the apparatus.
Professors Nichols experiments which
were carried on at the Yerkes observatory,
with the aid of thoroughly qualified assist
ants, were made with his torsion radiom-
eter a tiny air-tight case with fiuorite
window, containing a suspension of quartz
fiber with vanes of mica but 2mm. in di-
ameter. coated with lampblack. The YER
kes 24-inch silvered glass mirror, fashioned
by Mr.. G. Willis Ritchey. was. employed
to collect and supply the starbeams ana
the defiections were read at distance or
several feet with a telescope. The fun de-
scription of the apparatus. with the min
utiae of the experiments as published In the
Astrophysical Journal, would occupy more
than a page of the Ledger, but 1t Is
sufficient to state that the radiometer is
at least twelve times as sensitive as Boys
radiomicrometer, which would indicate the
one-millionth of a degree rise in temper
ature.
Experiment With Vega
Two well-known stars, Arcturus and
Vega, respectively probably 80 and 1000
trillions of miles distant from the earth,
and two planets, Jupiter and Saturn, were
selected for the experiment. All the pro-
cesses involved were dainty and aFduous,
and, as usual, mechanical and atmospheric
difficulties supervened, but the investiga-
ton was highly successful, and the aver
age of the observations, expressed In terms
of many millionth parts of the heat de-
1ection of a candle stationed at the dis
tance of single meter, showed that Vega 9
radiation is only half as great as that Of
Arcturus, while as to the planets Jupiters
detection doubled that of Arcturus, while
Saturns was only one-sixth as great as
that of it's congener.
AS matter of course, the observations,
though conducted with the greatest care,
must still be regarded as rough but so
approximately successful an attempt will
doubtless be improved upon in the near
future with instruments Of vastly greater
capacity, with a high resulting value to
astrophysics, for 1t will be noticed that,
while the photometric brilliance Of the two
stars is nearly equal, their tints are quite
dissmilar, and herein may yet be discov-
cred some surprising exposition Of the con-
ditions Of star life.