The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1899-09-30
THREE NORTH STARS.
Some of the wonderful Results of Spec
troseopie observation.

(From the Boston Evening Transcript
For many years scientists have known
Of the existence Of faint compa MON to
the North Star. So close and faint il this
companion that ownsrs of small telescopes
have often used 1t to test the power of
their eyes and Instruments News has
lately come from the Lick Observatory at
Mt Hamilton, California, of the discov-
cry that Polaris consists OF three stars,
centre Of gravity in about four days. At
the same time thess two revolve around
a third star In much the same way as
the earth and moon revolve around the
sun. In this cass the tsst is so severe
that no telescope can see the Individual
stars. We can only infer their existence
by noticing peculiar phenomenon in the
spectrum of Polaris.
The stars. and, In fact, all luminous
bodies, emit series Of waves which are
transmitted by the ether to rs. Those
waves that fall upon the retina of our
eyes produce a senation~that we oil light.
In the csse of many millions OF stars the
effect of these waves upon our eyes Ia in
appreciabls. Without the aid of some in
strument such stars ara invisible The
lens of telescope condolences a large area
Of waves into q small compass, and this
increases the effect upon the eyes OF the
observers. Consequently telescopes with
large lenses can gather in 50 much light
as to make exceedingly faint stars visible
to the observer.
But light has another characteristic be-
sides fntenstty-that 10, color. When a
certain number of waves enter the eve
ench secsnd we call the resulting ssnsa-
ton red. When larger number enter
each second we call the sensation violet,
eto. IL the light gathered by some large
telescope passes through . prism, or, bet
ter several pfisms, the different coIurs
are arranged in this order of their wave
length. Such an arrangement of ooIors
has been named the spectrum.
The spectrum of the sun and of most of
this stars Is crossed by a number of fine,
dark lines. These lines are really gaps
caused by the absence of rays Of light Of
certain wave lengths. The light, before
fs can reach our telescope, has TO pass
through an extensive solar atmosphere
which absorhs certain parts. The gaps In
the spectrum caused by atmospheric alb
sorption of the gun and stars are called
lines.
Wudn ~ lumluOus Dou} IS AT rest, the
waves OF light ara emitted In all eirso-
tions alike But when is IA moving
rapidly the waves In front are crowded,
while those In the rear are correspond
ingly heightened. OF course. at the sldcs
tbs waves continue to be emitted at their
normal ways length. The same pherome-
non is exhibited In sound II an exprsss
train whistlas as 1t passes, the pitch Of
the whistle 10 perceptfb1y lower when the
train Is receding than when IL 10 ap-
preaching. Tnereforc, when the star Ia
approaching the earth with sufficiently
large velocity, all the lines are displaced
q triiis toward the violet, that being the
color with the shortest wave length.
Conversely, when the star is recetiinQ
from the earth the lines are displaced
toward the red end Of the spectrum. Thfs
displacsmsnt h 20 sxossdinsly slight that
measurements OF its amount have had lit.
tie value until recently. The frat sue
csssful Investigation onsthe motion in the
line Of sight WINS upon the rotation of the
ann BY Vegel In 1871. Since then Tho
speotra have bean photographer and
measured In this way dispfacsments
corresponding TO . velocity cen siderably
less than Intls Per second can b detsos-
cd. . -.