Harrisburg telegraph. [volume] (Harrisburg, Pa.) 1879-1948, 1919-06-04
CURIOUS MYSTERIES
OF THE DAY
BY GARRET P. sERvIss.


viii you kindly tell me when it
Is Tuesday here, what time and
where on our globe will Wednesday
come in?-J. w. s., Providence"
The days are born and die on
line running from pole to pole which
is theoretically exactly opposite, on
the globes surface, to the meridian
of Greenwich. In strict fact, for
various reasons of local convenience,
this "date-line" does not, through
out its entire length Cone semi-cir-
cumference of the earth), keep pre-
cisely opposite to the Greenwich
meridian, but broadly speaking it
does, and the deviations need not
be considered, as they do not af-
feet the result for us on this part
of the globe.
The date-line runs through the
Pacific Ocean. far from land, which
is most fortunate circumstance.
If the whole circuit of the earth
were occupied by inhabited lands
there might be a good deal of con-
fusion in regard to the days of the
week.
People who confine their atten-
ton to the place on the globe
which they happen to occupy feel
no difficulty about the change from
Tuesday to Wednesday. They may
even be greatly surprised to hear
that there is any difficulty about so
ple-seeming a matter. For them
Wednesday begins at the moment
(midnighD when Tuesday ceases to
be. Every day is just twenty-four
hours long, and they come swinging
by like an endless chain consisting
of seven links. Where's the trouble
with that?" some ask.
The trouble is just here: The
length of day (really a day and
night counted together) is deter
mined by the time it takes the earth
to make one rotation on its axis with
respect to the sun. 1t is this rota-
ton that makes the sun appear to
rise and set.
BY universal agreement the day
is said to begin at the instant of
midnight, and the middle of the
day comes at noon. Now suppose
that, instead of staying in one place
on the earth, you should travel
westward, which is the direction in
which day advances, and imagine
that you could travel just as fast
as the earth rotates, but of course
in the opposite direction.
Then, If you started at Tuesday
noon, it would be always Tuesday
noon for you as you went westward
round the world. You would have
no change of day whatever; the sun
would be continually overhead.
Nevertheless, when you got home
again you would find that the people
there called it Wednesday noon.
Without being aware of the fact,
then, you must somehow, some
where. have passed from Tuesday
into Wednesday (using these names
in a worldwide sense). and that
happened unnoticed by you because
you had the sun always moveless
overhead when you went from east
to west over the date-line.
And next, little thinking will
show you that if you went around
the earth travelling eastward instead
OF westward, or going contrary to
the sun, at the same speed as before,
and also starting at Tuesday noon;
you would meet the noon sun again
twelve hours after you started; and
that would be, for you, Wednesday
noon. Twelve hours later still, when
you had come round to your starting
point. you would a second time en-
counter the noon sun, and conse-
quently you woull call the date
Thursday noon, although by the
reckoning of the people there. who
had not stirred from home, it would
be only Wednesday noon.
Similar results would be obtained
without travelling so fast. You might
take a year, or a whole lifetime, for
the journey, but still if you went all
the way round westward you would
lose a day as compared with those
who stayed at home. while you
would gain a day If you went the
other way around.
This shows the importance in
world business, as compared with
mere local affairs. of having a fixed
and universally recognized line on
the earth situated as far as nosSihIa