Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1896-04-12

weighs a little more than twice As much as
the other.
But this IL not all. A. Professor Picker
ing left the subject there was notnlng 70
determine the real size OF the stars, OF
the diameter Of the race tracks on wnicn
they are run. He pointed out way, now
ever by which they could be found out II
one could only make observations SUM-
GENTLY precise; It depends upon the use
OF the spectroscope. that wonderful IN,
strument which has almost Reconstructed
astronomy within the last forty years.
yOGEI,s OBSERVATIONS.
when we look ut star with the spec
troscope. we see, instead OF a star.
narrow stripe OF faintiy.colored light.
with certain dark lines across 1t; and, III
a star is coming toward us. these lines
are all pushed out Of their natural POSI-
tIon a little toward the blue end OF the
snectrum: while, II it Is receding, tney
are displaced In the opposite direction'
pv careful measurements on the hnes
ono can therefore find out whether
star "a moving toward or from US, anu
how fast. Now for the application:
mr. vopel. OF Potsdam, in Germany
srst succeeded In making the necessary
observations In 1850 he arranged az IN
strument with which he photographed
.ha snectrum of the star In all stages
90 ita evolution, and by measuring 'he
photographs under poweriHi ihicroseope
he showed that about seventeen hOuIs
BEFORE the minimum the bright star II
rocsdIng from us at the tremendous rate
~ twenty-six and a'haif miles second
svhua seventeen hours after the MINI
mum II Is rushing toward us with pile
same speed We know, tneh, INC ~
c,mference Of the circle on which TINS
star moves by simply. multiplying 'nv
number OF seconds In sixty-ohe noui, ~
,ts velocity OF twenty-six ana one laih
miles a second; and all the oeher uii M.
sIons Of the figure follow easiiy iioi''
this. -. ,.,,oh how
&c not 10 be considered absolute
~ 80, lint only as near the truth as
- cor GET AZ present. and probably very
,'oar,v right the bright star being de-
slgnated as A and the dark oouy Do ID
distance between centres OF tt.
and y .S,0SOo mics
diameter Of A M
D.. 90 y ...... S30OO miles
velocity OF A-26 IL miles per secoiiu'
Velocity Of B--55 miles per secohd'
According TO this A Is considerav,y
,oroe, than the sun. and Is is uho
smaller: but from the motion OF the Dou'.s
a. con he shown that their united mass -
III. ahout two thirds that OF the SUM- ana
,haIr density only one fourth as grea', ~
that they are much lighter tnan W.,
and cannot be solid bodies. but only nav
cIouds-A being much more prliilan' - To-
the SUM- while B, for some reaso" NV
determined. Is dark. N ,ha
sI,ni "a the only fixed star In all the
haayans whose size we know; as Tor an
the rest we can only guess at tneir lcai
no onitude. But this is not all the suahee
story of our star Observation mas ihaus -
syotn that the interval between its MINI
70 has been slowly changing for the pase
hundred wears. first frightening, put iale,
Shortening. so that at present IL 10 coS
six seconds shorter than II was IN DooH
ricke's time. -, hos sbown
.hn, ,his effect runs through its changes
"a about 100 years, and can De eNpiaino"
~, sunnosIng that Algol and Its compah.
IN are both moving together In greae
nrh,t as large as that of tho planet ira
80 under the attraction Of some lnVlsi-
HE body that controls the movement.
Tbere NAV be, however, some DOUBT a.
70 this explanation. since I1sser1ho, un'
of the ablest OF the French as'roiio'ls.
shows that a very different one is poS''-
BILE, and perhaps more prooapIe; l., ,ha
Algol will always be memorable IN tie
b,storv of astronomy as the first variable
star whose changes were thoroughly STU
died and satisfactorily explained, AZ being
the first star whose size has been mea-
sured. and as having first made certain
the existence OF stars darks. and 10 US
Invisible. but intimately connected Win
brightly luminous partners.
There are about dozen other Varlao,
s+ars which undergo changes OF the same
Sort as Algol's. but they are mostly
faint. and II may be long before We shall
he able to deal with them In an equally
satisfactory manner.