The Cape Girardeau Democrat. (Cape Girardeau, Mo.) 1876-1909, 1892-09-03
REGULATING TINE.
The Intricate System Of the Navy
Department.
An Electric Spark Sets All the Big Clock
in the Country and Tells Us When
1t IL Noon in wash
fngton.

fngtous
Away ont at the western end of the
city of Washington is a wooded hill
overlooking the Potomac, and forming
part of a large government reservation
or park, which reaches down t. 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,
and plays a very important part in the
daily affairs of the country; for it is
here hat standard government time is
reckoned for the use Of the depart
ments, and for the primary purpose of
testing and rating the thermometers
used on the United States war vessels,
and it is from this observatory that
standard time is regulated all over the
country.
Precisely at nc each day it sends out
III 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
ser ont at the right time, it is neces-
sary hat the officers in charge of the
government time service at the OBJ
s~ervatory should know at just what
instant the sun crosses the seventy
fifth meridian, or is directly above the
meridian s~eventy-fve degrees west
longitude, which, as you have learned.
is one of n number of imaginary lines
stretched from pole to pole across the
earth's surface, and reckoned 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
the sun gets exactly over that line it is
twelve o'clock at Washington, eleven
o'clock at Chicago, ten o'clock at Den
yer and nine o'clock at San Francisco;
for. as you perhaps know, according to
this system of standard or railroad"
time lit being originally adopted for
the convenience of the railroads) the
country is divided into four sections
Eastern, Central, Mountain and Pa
~ciic-each just one hour in advance of
the other, and time at all places in the
same section is the same. Accordingly,
when it is noon at Washington it is also
noon at Philadelphia, New York, Bos-
ton and every other place included
within the eastern section. This, of
course, is not strictly correct, for 1t is
really loon at only such places
through which the seventy-fifth merid-
ian happens to pass, as the true noon
day of a place is when the sun is direct
Iy overhead. Washington, for example.
is on the sev~enty-seventh meridian, or
two degrees farther west, and, conse-
quently, according to its local time it
is only eight minutes OF twelve, while
the true time of Boston, which is tour
degrees to the east, is sixteen minutes
in advance. But if every city were to
use its own time, it would, in many
cases, give rise to a good deal of confu-
sion and Inconvenience; and it was for
the very purpose of avoiding this that
the present system Of standard time
was adopted.
As we have seen, the time for send
ing ont the noon signal from Washing
ton Is the instant the sun crosses the
sevehty-fifth meridian. This, however,
is not the sun which gives us light and
heat, but an invisible, imaginary one;
because, for certain reasons, the true
sun does not cross the meridian at the
same moment every day, but during
one part of the year he gets owe it a
little more ahead of time each day, and
during the other part he is correspond
ingly behind time; and SO this fictitious
sun is used, because its apparent path
around the earth brings it exactly over
the same line at the same moment
every day. Now at just what instant
this sun crosses the meridian is deter
mined by means of the stars; for time
at the observatory is not reckoned by
the sun, but by the stars.
Every clear night an astronomer ut
the observatory looks through a large
telescope for certain stars which he
knows must cross a certain line at GER
tain times, and by the use of an cleo
trical machine he makes a record of the
time each star passes, as shown by a
clock which keeps sidereal or star
time. lie then consults a printed table,
which shows him at just what time
each star must have passed, and by rs
much as this time differs from that re;
corded by the clock the latter is wrong,
and in that way the sidereal clock is
regulated. This star time is then re-
duced to sun time, which requires some
calculation, as there is a difference be.
tween the two of about four minutes
each day, a sldereal year consisting of
just one day more than a solar year.
7 hese two clocks-the one keeping
star time, and the other sun time-are
OF very fine quality, and are as near
perfection as possible. Although they
cannot help being affected by changes
of temperature and different condi-
tions of the atmosphere, they very
rarely are more than a fractional part
of a second out of the way. No at
tenipt is ever made to correct such err
rors, but they are carefully noted and
allowed for in making calculations
For the purpose of distributing time
a third clock, known as a transmitter.
is used. This is set to keep time by the
seventy-ifth meridian, and is regulat-
ed by the standard clock before men,
toned. 1t is, in all respects, similar to
the other clocks, except that it has at
tached to it an ingenious device by
which an electric circuit may be alter
nately opened and closed with each
bt at of the pendulum. This clock con-
trolls such circuits, of them being
used for dropping the Washington
time ball, and the other onc connect
ing With the several telegraph instru-
known as repcaters, WHICH
on Il case near by. These instf6-
in turn connect with the tele-
graph c,mpany's offices at Washington
and New York. and control the WASH
Hre-alsrm circnit and the OBJ
s~crvasosr clock line By mean Of The