Abilene weekly reflector. [volume] (Abilene, Kan.) 1888-1935, 1892-12-15
REGULATING TIME.
The Intricate System of the Navy
Department.
An Electric Spark Sets All the Mig Clocks
In the Country and Tells Us When
It IL Noon In Wash
tngton.

| tngton.
Away out at the western end OF the
city Of Washington Is a wooded hill
overlooking the Potomac, and forming
part OF large government reservation
or park, which reaches down TO the
rivers edge. On the top OF this hill,
remote from all the other public build
ings In Washington, stands the United
States naval observatory.
This branch Of the navy department
Is OF great service to the government,
aud plays a very important part in the
daily affairs Of the country; for it Is
here that standard government time Is
reckoned for the use OF the depart
ments, and for the primary purpose OF
testing and rating the chronometers
used on the United States war vessels,
and II is from this observatory that
standard time is regulated all over the
country.
Precisely at noon edch day II sends out
an electric signal TO the various govern
ment offices and buildings throughout
the District of Columbia, and, by means
of the telegraph, this same signal is
flashed over the United States at the
same instant.
In order that this signal may be
sent ont at the right time, 1t is neces-
sary that the officers in charge Of the
government time service at the OBJ
servatory should know at just what
instant the sun crosses the seventy
9th meridian, or is directly above the
meridian seveuty-hve degrees west
longitude, which. rs you have learned,
L.. II - Tina t.,a ltnaa
, stretched from pole to pole across the
earths surface. and rcclSoncd accord
\ ing to their distance east or west from
, Greenwich. Now, this seventy-ffth
meridian has been chosen as the stand
ard for regulating time, so that when
y the sun gets exactly over that line IL Is
' twelve o'clock at Washington, eleven
l. o'clock ut Chicago, ten o'clock ut Dem
yer and nine o'clock at San Francisco;
} for, rs y on perhaps know, according TO
y this system of standard or railroad"
. time lit being originally adopted for
y the convenience of the railroads) the
country is divided into four sections
: Eastern, Central, Mountain and P0-
: cific-cach Just Que hour in advance Of
:. the other, and time at all places in the
/. same section is the same. Accordingly,
when II is noon at Washington it is also
u, noon ut Philadelphia, New York, Bos-
!, ton and every other place included
within the eastern section. This, OF
ID course, is not strictly correct for IL "a
4 really noon at only such places
Of through which the seventy-fifth merid-
Of ian happens to pass, as the true noon
th day OF place Is when the sun is direct
q, ly overhead. Washington, for example
IS Is on the seventy-seventh meridian, OF
he two degrees farther west, and, conse
rs quently, according to its local time II
10 Is only eight minutes OF twelve, whil'
he the true time OF Boston, which Is foui
ld degrees TO the east, is sixteen minute
ul In advance. But II every city were :,
use its own time, it would, in man,
nj cases, give rise TO a good deal Of confu
he sion and Inconvenience; and 1t was 70
j the very purpose of avoiding this tina
IT the present system of standard tim
J was adopted.
OK As we have seen, the time for send
~ ing out the noon signal from Washing
"a ton Is the instant the sun crosses tn
seventy-ffth meridian. This, however
is not the sun which gives us light au
heat, but an invisible, imaginary one
: because, for certain reasons, the tru
sun does not cross the meridian at tn
n same moment every day, but durin
one part OF the year he gets over II
c little more ahead Of time each day, au
during the other part he is correspond
ingly behind time; and so this fictitiou
/ sun Is used, because its apparent pat
around the earth brings II exactly owe
e the same line at the same momeI
q every day. Now at just what instar
this sun crosses the meridian Is detel
mined by means OF the stars; for tim
at the observatory Is not reckoned b
the sun, but by the stars.
C Every clear night an astronomer |
the observatory looks through q larG
J. telescope for certain stars which b
a knows must cross certain line ut ce
- tain times, and by the use OF an Gle
:. trical machine he makes record OF u
time each star passes, as shown by
= clock which keeps sidereal or ST
ct time. lie then consults printed tabl
which shows him at just what tin
each star must have passed, and by
much as this time differs from that r
is corded by the clock the latter is wron
,sr and In that way the sidereal clock
regulated. This star time Is then 7
duced To sun time, W1ish requires SOU
calculation, as there Is n difference b
- tween the two OF about four minut'
each day, sldereal year consisting
lust one day more than a solar year.
These two clocks-the one keepil
49, star time, and the other sun tlme-a
n of very fine quality, and are as ne
q perfection as possible. Although tn
tho cannot help being affected by chang
"a OF temperature and different cont
VE tions Of the atmosphere, they We
rarely are more than a fractional pa
ds. OF u second out OF the way No
-, tempt is ever made to correct such I
rvs rors, but they are carefully noted al
zen, allowed for IN making calculations.
''eo For the purpose of distributing Tn
,eri "a third clock, known rs transmits
neY is used. This is set TO keep time by !
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