The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1905-01-15


1 ent diurnal motion is owing 10 the ac
tual rotation of the earth on it's axis,
/ and its apparent annual motion is due
/ 10 the revolution OF the earth about
! the sun in the plane of the ecliptic.
4 which is inclined to the plane of the
equator at an angle of % deg. Il min.
called the obliquity of the ecliptic. The
( latter undergoes a very slight but con-
/ tinuous change, until il VIII reach its
: minimum, no less than I5,000 years
| hence. when it win be % deg. Is min.
! After having obtained this minimum
IT VIII begin t. increase again. The
fact that calculations can be made in
NolYing such minute changes within an
enormous period of time furnishes a
splendid Testimony to the wonderful
3 power Of Mathematical analysis and
/ the ingenuity OF man in applying il to
I the gTandest science that has ever been
/ devised. The T-tiOn of the earth
around the great Iuminary, the sun, is
not uniform, for il is performed not ~
a circle, but in an elongated curve, the
eclipse. But even if the earth's motion
| in the plane OF the ecliptic were circu-
/ air and uniform, the apparent motion
Icf the sun north and south of the
equator, or TO use a technical phrase,
! in deciination, would still be variable.
for meridians that divide the ecliptic
! into equal parts do net divide the
equator into such.
The reader not wholly unacquaiated
with spherical geometry viii readily
understand the reason for this In con-
sequence of the unequal motion of the
sun ia defamation it viii move at GER
tain times faster or more slowly than
at ether times. Near the equator the
sun moves fast, whereas near the
points of its nOrthernmOst and south
ernmost limits il moves very slowly,
nay. at these limits themselves, il
seems to stand still for a time. for
which reason these limits are called
solstices. from the Latin, meaning the
standing still of the sun
The motion of the sun i'm declinatiOn
is of the highest Importance. as the
seasons of the year and the shifting OF
the points of the suns rising and set
ting depend upon il. In this obliQue
motion of the sun with reference to the
equator must ais be distinguished its
motion in right ascension from that in
declinatiOn, the former being along, or
rather parallel to the equator This mo-
tion is necessarily variable, tCo. The
angle which the diurnal paths of the
sun and the stars make with the hOTi-
ION, depends altogether upon the lati-
tude of the place of observation. At the
equator. for instance. the diuTnal cir
cles Of the sun and stars cut the hCri-
ION at q right angle. whereas at the
poles they move parallel to the horizon,
which in this case is the equator ON
all intermediate points the angle is
obliQue. its magnitude depending upon
the latitude OF the place.
These three positions are respective
" called the right. the parallel and the
Oblique spheres. The latitude of a
place is always equal to the elevation
of the pole above the horizon fact Of
the highest Importance and worthy &C
the earnest attention of the reader. BY
means of an instrument called the sex
tant, the manipulation of which is quite
simple, the traveller can always, with
tOlera BILE accuracy. determine the lati-
tude Of the place where he happens to
be. by observing the elevation of the
pole star from the horizon In the
is not marked by any star in close
enough proximity, this observation
would be more difficult. 1t is neces-
sary to say here that the pole star does
not exactly mark the true pole of the
heavens around which the whole irma-
ment makes one circuit every day.
At present it is I degree Is min dis
tant from the true pole Four thousand
years ago ii was at a far greater dis
lance from il. If we connect the
brightest star i'm the bowl of the little
dipper with the last star but one in
the handle Of the big dippeT by a
straight line and bisect il, the point of
dissection is marked by a sufficient
bright star in the constellation BRACE.
called Thuban. which formerly was the
pole star. Our present pole star Will
approach the true p-le of the heavens
within half degree of it. This limit
III De reached IN ABOUT a century,
after which it will Tecede more and
more. and in about 1900 years our pole
star will no longer act in that capacity,
but yield that privilege to the brilliant
first magnitude star Vega.
This change of the position of the
pole Of the heavens is due to what IS
called the procession OF the equinOXes,
a subject Of the highest importance
and interest, which we shall explain as
briefly as possible, as space forbids us
! 60. -. r
The points where the ecliptic intersects
the equator are called the vernal and
autumnal equinOXeS. These points
have been observed to move slowly
westward at the rate of 80 seconds a
year. The effect of this So-called "a
misnomer. since il is really a recession)
is the change Of the pole of the heaV-
ems, and a backing westward of the
signs of the zodiac into the constella-
lions west Of them. Another effect is
the difference Of the tropical year from
the sidereal, the former being 20 min
utees shorter than the latter. As TO the
physical cause of the procession of the
equinoxes, we confine ourselves to the
remark that il arises from the fact that
the earth is not "A sphere and Of the
tendency Of the plane Of the equator TO
coincide with the plane of the ecliptiC
in consequence Of the attraction of the
sun and moon upon the equatorial ring.
fun and entirely satisfactory eX-
DldiidllOll WOULD require Ultie ktiOWi-
edge of analytical mechanics than we
can in fairness suppose the general
reader to possess.
Laplace's Nebular Hypothesis.
The marvellous structure of the heav-
ems in general. and of the solar system
in special, cannot but arouse the nat
ural desire of knowing something of it's
origin. One of the greatest maizena,
ticians the world has ever seen, the
Frenchman, Laplace. furnished a the
DRY, which. with some necessary m5di-
fcatiOns, has been generally accepted
as the most probably true one He
supposed that millions OF years ago Can
accurate statement in this respect lies
beyond the limits of possibility. all
the matter of the sun, the planets
satellites and all the other cosmical
bodies subject to the attraction of the
sun. were diffused as a gas through
the space bounded by the orbit of the
most distant of these bodies. Under
the influence of the graVitatiOn of this |
immense mass of gaseous matter il as
sumed a glObular form with a rotating
motion around some axis In conse-
quence OF the gradual shrinking of this
rotating mass, the velocity OF rotation
was increased until at last a ring would
be thrown off. or TO state il more ac- !
curately. would be left behind. which
again by its inherent rotary motion,
would assume q glObular shape. This, !