The evening tribune. (Pawtucket, R.I.) 189?-190?, 1897-06-03

Going East and Going West and the Dif.
ference In Time.

Going East and Going West and the Dif.
ference In Time.
IT heard 10 recently stated that II two
men start from the Same point mt the samo
time, one going east and tho other west,
for journey around tho world, and each
resting on the Sabbath day, when they
meet they will be keeping different days
for the Sabbath. Is'this sof'
Astronomers reckon the day from noon,
when the sun crosses the Greenwich msrid-
Ian. But for convenience all civilized na-
tions begin the dayat midnight. IL has
also become the universal custom to reckon
time from Greenwich, using that longi-
tude for the prime meridian. Astronomers
count the hours of the day from 0 TO "a,
but custom makes us count up to ID and
then start all over, using the afax "a. M"
or "p. m" TO tell which half OF tho day
we are talking about. In different lati-
tudes OF the earth, the apparent time and
not the Greenwich mean time 10 used. AZ
the earth IL arbitrarily divided into $50
degrees Of latitude and a. the sun travels
over these $50 degrees every "a hours, an
hours time ID consumed In passing each
IL degrees. Hence In travelling westward
the pilgrim sets his watch back an hour
for every Is degreeM
In travelling toward the east, he sets HE
watch ahead an hour for each 10 degrees.
After travelling 180 degrees (half way
around the earthly the man who Travelled
westward has set his watch back Just 10
hours, while the man who travelled toward
the east has set his watch ahead 12 horrs.
Thus, as they meet, their watches again
agree upon the time. As they continue
their journey they keep changing their
watches every 16 degrees In order to keep
abreast with the apparent time. When
they arrive at the place Of starting, the
western pilgrim has set his watch back "a
hours Zone day) and tho one travelling
eastward has set his watch "a hours Zone
day. ahead, and both watches again re-
oord the same time of day. The first party
has therefore lost day and the second
party has gained day. It is consequently
necessary for the first party TO skip one
day on his calendar and for the second to
add one day in order to even things up.
As Greenwich time Is the recognized mean
standard, travellers make this change In
their calendar when they reach $50 degrees
east or west from Greenwich, In order to
keep on good terms with the almanac.
This point is not far from the center Of the
Pacific ocean.
In going to China from San Francisco
we therefore lose an almanac day, and in
f. returning we make 1t back. Hence when,
for example, it Is noon Feb. 20 (Washing-
toms birthday six inches east Of the one
hundred and eightieth degree from Green
wich, according to the almanac, at the
same time 1t is Feb. 90 six inches west Of
the same line. It is good thing that this
latitude lies in the middle of the Pacific,
where nobody lives Tho apparent time
which is actually observed for the Sabbath
does not wholly agree with the almanac
day except at Greenwich and for dis
tance of one degree east and west. Cast
ing aside clocks and almanacs and speak
ing Of apparent time only, which Is the
time we all use, it becomes evident that
from midnight till noon at any given
point of latitude 1t is always the day be-
fore on the opposite side of the earth.
From noon till midnight it Is the same
day. Thus, when we are attending 10
o'clock Sunday morning service in New
York, citizens Of Canton, China, are at
tending Saturday night ball or political
meeting. When it is exactly noon at
Greenwich, it is the same almanac day as
well as apparent day all over the earth,
and at no other time. me.-Brooklyn Eagle.