Evening star., 1922-10-22
u. S. NAVY RADIO SERVICE
is TIME CLOCK FOR WORLD
Many Errors in Ships Chronometers and
Land Pieces Are Corrected by
Daily Signals.
by COMMANDER STANFORD {
HOOPER,
United StnteS Navy,

by COMMANDER STANFORD c.
HOOPER,
United states Navy.
Every day Of the year. at certain
specified intervals. electric impulses
corresponding to the rhythmic swing
Ing of clocks pendulum. may be
picked out of the atmosphere in vir-
tually any part of the world.
These impulses constitute the "ra-
dio time signals daily broadcasted
from widely separated shore stations
of the Navy's radio system.
Because of their supreme impor-
tance to the mariner, the radio time
signals are given the right of way
in the ether.
The time signal service yields pri-
ority only to s. o. S. or distress sig
nails on the wave lengths and within
the areas affected.
They are broadcasted regularly and
without fail daily by the stations des-
ienated
Ships at sea within the areas af-
fected, cease handling radio traffic
during these intervals and carefully
observe the time signals for COM
parlson Win the Sh1pS ChronOmeterS
Affects Navigation.
Thousands of jewelers. throughout
the United States and elsewhere in
In these signals with their miniature
receiving sets for comparison with
their standard timepieces.
Time. being one of the two CO.
ordinates which fixes the position of
ship at sea. obviously is an eX-
a11- inn, nrfo oil In, i
cation.
Difference in longitude is merely a
question of difference of time.
The actua! longitude measured
from a given meridian is the differ
ence between the times measured
from that meridian and the local
time.
Local time is easily obtained. espe-
cially during clear weather. by OBJ
serving a heavenly body's altitude
and applying appropriate formulae.
Mariners carry delicate mechanical
timepieces tchronometers) regulated
to Greenwich mean time.
If the chronometer is absolutely
correct it accurately registers the
mean time, counting the meridian of
| Greenwich, England, as the zero
point.
These ships chronometers are sub
ject to errors and rates, >however.
and these must be determined to APP
obtain the correct Greenwich mean
time.
knowing this time and the local
! time, the determination of the longi-
tude resolves itself into Il question of
arithmetic.
The Importance to mariners of fire.
quently checking their chronometers
by some standard when at sea and
thus knowing the correct Greenwich
mean time. within at least a fraction
of a second, may be illustrated by
citing that four seconds on the eGua-
tor, for example. is sea mile.
Aids Ship Mariners.
1t is primarily for the purpose of
enabling mariners to observe the
Navy's radio service daily broadcasts
time signals from its more important
radio stations situated at widely
separated points within the United
States and in our outlying posses
sions.
The broadcasting of time signals
as an aid to navigation was begun
more than ten years ago. this being
the first radio broadcasting service
ever inaugurated in the world.
dispensable to our Navy and to the
ships of our merchant marine in all
waters of the globe.
1t has greatly improved the accu-
; racy of our timepieces on land as
well.
With the exception of the Darien
high power station in the Canal Zone
and the Pearl Harbor high-power sta
ton in the Hawaiian Islands. the time
signal impulses DroadcaSted by the
naval stations are actually transmit
ted by the pendulums of the master
clocks themselves at the Washington
u. c.. and Mare Island. Calf, naval
ObServatOrieS.
Those broadcasted by Darien and
Pearl Harbor are sent out from mas
ter clocks installed at these stations