Evening star., 1918-03-19

schedule. just as it drops now at noon
under the existing system.
Officials at the Navy Department say
that the standard clocks can be ad-
justed to meet the changed conditions
witheut the least trouble. After the
new time system has been in existence
a short time. they believe, the people
generally Will s~s ns aware OF the fa4ss
that their clocks and watches are IA
hour anead OF the time as fixed by ma
lures law. AS one officer puts it, ex-
listing sun diaiS are rne only man-made
time pieces that cannot be changed in
time to meet the conditions of man.
made law
Base of Time Calculations.
To meet the new situation. the sci
entists at the Naval Observatory mere
iy will have to base their time calcu-
lations on the Goth meridian (the Pitts
burgh district) instead of the 18th me-
ridian. as has been the custom for,
years past.
The usefulness to navigation and to
the country in general of the daily
time service of the Naval Observatory
has been increased within the last
two years by the installation of two
up-to-date transmitting clocks at the
observatory to replace the two clocks
which had been in use there for the
previous forty years. At the same time
arrangements were made for checking
the actual emission of the radio time
signals throughout the Country and for
several thousand miles at sea
Signals by Radio.
Under the existing. system time sig
nails are sent by radio. as follows:
From Radio. Ya.-Daily at noon and
iat 10 pm, 18th meridian time. wave
length $500 meters d
From Key West, Fla, and New Or
leans. La--Daily at noon. 18th meridian
time, wave length 1000 meters.
The transmission of these signals is
automatic from the observatory over
special wire to Radio. Va, and. by
courtesy of the Western Union Tele-
graph Company. over its wires to other
stations. For vessels navigating the
north and east Pacific ocean time sig
nails are sent out from the naval station
lat Mare Island Cal s.l-s..
3 BY these means the Naval Observa-.
tory supplies the people of the United
adjacent oceans with accurate standard
time twice each day throughout the
year.
Positions of Heavenly Bodies Noted.
In addition. navigators. surveyors
and astronomers of this and other
countries are kept supplied with the
positions of the heavenly bodies in a
form for practical use. through the is
J
the Nautical Almanac. Continuous
fundamental meridian observations of
the sun. moon. planets and stars are
kept up. throughout the year in order
to insure the highest attainable stand
ard of accuracy in the tables published
in the Nautical Almanac for computing
the times of sunrise and sunset anu
moonrise and moonSet.
Since October 9, 1914, certain stars
less than 10 degrees from the zenith
also have been observed for greater
accuracy in clock correction.
Selection of Greenwich.
Reckoning mean time according to
hours of longitude west or east of
Greenwich, England was decided rnOn
, at an international conference in this
city in 1854. Greenwich was chosen in
compliment to English astronomers
who had already established that as the
base dine for computations of time and
who had taken a foremost part in eff
forts to establish standard mean time
system for the world.
At the conference it was proposed to
| make the day begin at midnight to
correspond with the civil day, but as
astronomers always reckon the begin
ming of day at noon the proposition
met with opposition and never was
adopted, SO that the day still begins at
noon, according to astronomical obser-
walton.
Sidereal time is the time when the
! sun apparently crosses the meridian of
| observation. Mean time is that used bv
clocks and watches using standard
time. Only about March q OF each wear
are sidereal time and mean time in
actual correspondence.
| in figuring sidereaI time astronomers
/ taking observations on longitudes not
| that of Greenwich add or subtract
| 1856 seconds for each hour of lonpi
| tude the point of observation is west or
! east of Greenwich.
French Computes at Paris.
| French astronomers use the lonpitud.
! of Paris for computing side-reaI time
! The United States uses four merjdjs,s
of longitude in computing mean ,r
standard time-75 degrees, 80 degrees
lo5 degrees and 12O degrees west Of
\ Greenwich, dividing the country ;,t,
| four zones of eastern, central n,ouptai
and Pacific time, these being resnecti,ra
| ly five, six. seven and eight hours waS,
! of Greenwich.
| These standards of time were nu+ in
use by the railroads. which wera O..
! lected by the scientists of the intsrn.,-
| tional commission as the logical apen-
cies for Instituting the change
| Norway, Sweden. GERMANY Aus+ri,
| switzerland and Italy stin use mid
! European time as their mean time this
| being one hour faster than Greenw;ch
time South African time is two bonrs
| faster than time based o4l the Creon'
! wich meridian.