Omaha daily bee. (Omaha [Neb.]) 187?-1922, 1917-04-02
By GARRETT p. sERvISs.

Human life is too short-not for
making money, or for becoming
great man" temporarily, but for get
ting practical knowledge Of the great
year OF the equinoxes, and enjoying
the swing of the earth's poles as they
circle around the poles of the ecliptic.
This motion Of the poles, combined
with the squirming around OF the
earth's orbit in space, periodically
revolutionizcs the climates in the
northern and southern hemispheres.
But one would have to live $1,000
years in order to go through a single
cycle Of the vast changes which are
produced in the course of this. super
year, and If man could survive sixty
or seventy of these periods as he sur
wives the same number OF common
years. he would probably reckon his
tory by the succession of genial and
glacial epochs instead of by that OF
ordinary winters and summers.
Here is the whole thing in nut
shell. The earth turns on its axis
once in twenty-four hours and gives
us the succession of day and night; it
revolves around the sun once in sos
days and gives us the yearly changes
of season; its poles revolve around
the poles OF the ecliptic once in 2o,000
years and gives us the super-year,
whose length as measured by its Ell
feet on the season, is cut down to H.
600 years by the creeping, or squirni-
ing, OF the orbit. But this last cycle
is known to us only by virtue OF our
intelligence, since our lie is but an
insects span in comparison with it.
- To understand this, let US first re-
call that the ordinary changes OF sea-
son are due to the fact that the axis
around which the earth rotates does
not stand upright to the plane OF its
orbit around the sun (Which is the
plane of the ecliptic), but is inclined
about 23h degrees from perpendicu-
lar position. That being understood,
the next thing to remember is that
the earth's axis, although inclined, IS
nevertheless fixed in position, j, e., it
always points the same way in space,
so that, as the earth travels around
the sun first one end, or pole, OF the
axis leans toward the sun, and then,
when the earth has gone, half way
round its orbit, the other pole leans
toward the sun. 80,
We call one end OF the earth's
axis the North Pole and the other
the South Pole. When the North
Pole leans sunward the South Pole
leans away from the sup, and vice
versa.
But when either pole inclincs
sunward the sun rises high over
the hemisphere to which that pole
belongs, and so summer prevails
| in that hemisphere, while it IS
winter in the other hemisphere, he
cause there the sun runs low in the
sky. These conditions are reversed
once every twelve months, each hemi-
sphere having summer halt and a
winter half OF the year, spring and
autumn being simply transitional per-
iods.
The two halves OF the year would
be exactly alike in each hemisphere
| il the earth's orbit around the sun
were perfect circle, with the sun in
the center. But, in fact, the orbit is
an ellipse, or oval, with the sun sit
uated in one OF the foci OF the ellipse,
about 100000 miles to one side OF the
middle,
One result of this is that the
distance OF the earth from the sun.
about 100000 miles on the average,
changes to the extent of 100000
miles in the course Of every six
months. The nearer it is, of course,
the more heat it gets. At present
the increase of heat at "perihelion''
(the nearest point is about 8 per
cent above the amount at "aphelion''
| (the farthest point.
i Now we come to something oi
the highest importance to US who
live in the northern hemisphere. II
happens at present that the earth
is in perihelion just at the time when
the North Pole leans away from the
sun, and in aphelion when it leans
toward the sun. The consequence
is that we have winter when the earth
is nearest the sun and our summer
when It is farthest from the sun. Thi:
naturally tends to diminish the effect,
Of the difference in the amount oI
heat received at the two seasons
Our winters are less cold than they
would be II they occurred with the
earth in aphclion, and our summer:
. less hot than IL they occurred with tn,
. earth in perihelion,
But there is still another thins
: which favors us for the time being
! and that is that, since the earth trav