The Anaconda standard. [volume] (Anaconda, Mont.) 1889-1970, 1898-12-04

TO be found out from catalogues. or
have to be observed with the transit
circle. but when they are known the
position OF the comet or minor planet
| can easily be inferred.
IL is only recently tina Greenwich
has taken any great part in this work.
In the main. double star has
been in the hands OF amateurs. at least
in England. Blu the discovery In re-
cent years OF many pairs so close that
a telescope of the largest size Is re-
| qulred for their successful observation
has put an important section of double
stars beyond the reach OF most private
observers. inc therefore the great tele-
scope at Greenwich is now mainly de-
voted to their study.
There Is a striking contrast between
the great telescope and all the massive
machinery for its direction and move
ment. and the objects on which II Is di-
r~ected-two little points of light sep
arated by a delicate hair OF darkness.
The observation is very unlike hose
of which we have hitherto spoken. The
object is not to ascertain the actual
I, position in the sky of the two stars. hut
their relative position to each other. A
spiders thread of the finest strands
is moved from one star to the other by
turning an exquisitely fine screw: this
enables US to measure their distance
apart. Another spider thread at right
angles to the first Is laid through the
centers Of both stars. and a divided cir
Gle enables US to read the angle which
this line makes to the true east and west
direction. Such observations repeated
year after year on many stars have en-
abled the orbits of not a few to be laid
down with remarkable precision, and
we find that their movements are COM
pletely consistent with the law of grav-
itation.
Further. just as Neptune was prerec-
ognized and discovered from noting the
irregularities in the motion Of Uranus.
so the disturbances in the place of ST.
rius led to the belief that IL was at
tracted by a hen unseen companion
a companion whose position with re-
spect to the brighter star was predict
ed and afterwards seen.
Gravitation then appears. indeed. to
be the bond of the universe. yet IL
leaves us with several weighty prob
lens. The observation of the positions
of stars shows that though We call
them fixed they really have motions OF
their own. or these motions. a great
part consists OF a drift away from one
portion OF the heavens towards a point
diametrically opposite to II. a drift such
as must be due. not to a true motion
OF the individual stars, but to a mo-
ton through space OF our sun and its
attendant system. The elder Herschel
was the first to discover this mysterious
solar motion. Sir George Airy and Ed
win Dunklin, for 46 years a member
OF the Greenwich staff. and from 1ssl-s4
the chief assistant. severally contrib
uted important determinations or Its
direction.
What is the cause of this motion.
what is the law OF this motion. Is at
present beyond our power to find. Many
years ago a German astronomer made
the random suggestion that possibly we
are revolving in an orbit round the
pleiades as a center. The suggestion
was entirely baseless. but unfortunate
ly has found its way into many popu-
lar works. and still sometimes Is
brought forward as II II were n OF
the established truths OF astronomy.
We can at the present time only say
, that this solar motion Is a mystery.
There is.a greater mystery still. The
stars have their own individual mo-
tons, and in the case Of a few these are
of the utmost amazing swiftness. n
/ earth I'm its motion round the sun trav-
els nearly 10 miles In a second. say one
thousand times faster than h quick
est rush of an express train. The suns
rate of motion is probably not quite so
swift. hut Arcturus. a sun far larger
than our own. has "A pace some 20 times
as swift as the orbital motion OF the
earth. This il not a motion that we
can conceive of as being brought about
by gravitation. for II there were some
unseen body so vast as to draw Arc
turus with this swiftness. other stars.
too, would be hurting across the sky
as quickly. lii Job OF old, we are
speechless when the question comes To
us from heaven, 'Canst thou guide Arc
turus and his sons"
f. WALTER MAUNDER. F. r. A. s.