Evening star., 1935-07-07

4AeH' Va Jul " CocuL BTcdLly ADVANCED
knowledge. We have travelled q long.
long way from the fire bell ringing
In the City Of Washington to the re-
Gently received information that Nam
king, 1,200 miles up in the interior
OF China, Is receiving our hourly
broadcast with perfect clearness and
uninterrupted regularity. A Chinese
scientist who visited Washington re-
Gently reported that the signals come
In clear and strong. Naturally, think
ing that he must be receiving one
OF our regular six daily more powerful
signals, that possible confusion was
discussed. He interrupted by remark
ing, No, we are receiving your 20
times-a-day automatic signals. and
we have calculated that these signals
must reach us by way of the North
| Pole"
Immediately pinned . line 10
Washington on a terrestrial sphere
and hauled 1t taut to Marking, and
the line cut over the Pole.
| a CCURACY of timekeeping has al
ways been dependent upon the
accuracy Of the various types of
clocks plus the accuracy OF time de-
termination. Each advance in the de-
velopment of clock precision has been
heraIded with great satisfaction. For
years the Nations time has been
maintained by the very best precision
! tlmepleces obtainable and has been
broadcast by mean time pendulum
controlled clocks. But what advances
have been made in the accuracy Of
time determination? It Is true that
standard practices were closely scru-
tinized to insure accuracy, but that
Is all. The Naval Observatory has
again pioneered in this field. After
experimental work over a considerable
! period of time an old instrument
was modified to meet the new de-
mands and now a fully developed
Photographic time determination svs-
TEN has been built and Is In con-
slant use.
This Photographic method Of tine
determination eliminates entirely the
personal error Of the observer and
also permits repeated checking, thereby
| eliminating another possible source OF
/ variation.
This Photographic method Of time
/ determination, plus the automatic
method Of broadcasting, gives the
United States Naval Observatory the
most up-to-date installation In the
world. 1t is not believed that an
other nation has paralleled our latest
developments.
Crystal-controlled clocks have Iona
been recognized as the very highest
precision timekeepers. Without going
into the origin or the development OF
this system, which is thoroughly
known, suffice it to state that this
development has centered around the
design of constant-frequency oscil-
lators, and these oscillators have been
developed with very high degree OF
accuracy. A Synchronous clock driven
from one of these oscillators is a cor
respondingly excellent timekeeper.
The constant-frequency system used
at the Naval Observatory differs from
that employed in the usual frequency
Standardization systems. 1t is not de-
sirable to go into any details Of this
subject at the present time. Possibly
in six months or year this NAV be
possible. Two sets have been built.
One is used at Mare Island and the
other at the Naval Observatory. As
soon as Congress makes funds avail
able two more sets will be con-
structed-one for Honolulu and one
for Panama.
AS soon as the Government has
patented this device, the Chinese
scientist who has been visiting us for
the past month wishes to purchase a
complete equipment for installation At
Marking.
1t is devoutly hoped that he will be
able to obtain the necessary funds
to cover this expense as it will be a
tremendous advantage to have an
American time service complete in all
details established way up in the in
terror of China. half way around the
world.
WITHOUT exposing any Of the
w principles of the system, 1t Is
stated that previously it required is
minutes for the astronomer to make
q chronograph comparison between
the transmitting clock with the stan
dard clock in the vault, calculate ana
apply the electrical correction, and
have the clock in all respects ready for
broadcasting. Now it can be done IN
about five or six seconds mechanically
and without chronogrsph comparisons
or calculations. Before, it was neces-
sary to make this comparison previous
to each broadcast, now we make this
comparison twice a day although once
a day would be sufficiently accurate.
After the daily comparison. the en-
tire procedure is automatic. At f1vs
minutes before the hour the broad
caster throws its own switch and
makes the signal through Arlington.
The master switch, previously thrown
by the man on watch at Arlington on
automatic signal from the Naval OBJ
servatory, completes the circuit, and
from that time on everything Is COM
pletely automatic. The time signal,
with its identification signals, ETC., Is
transmitted with much greater ac-
curacy than previously. After the
signals are on the air, they are picked
up by the antennae at the observa-
tory. They are received on five diff
ferent receiving sets specially built
according to the observatory's own
design, and are converted into me-
chanical energy and operate q printing
chronograph. This gives us a com
plete written record Of every star OBJ
served, every signal going out, and
every signal received over the cir
These records make it possible to make
extremely accurate comparisons.
Only once since September 7 has
this broadcsster failed, and remember
it has run a hours q day since the
| Tth ~ Sapfapoher I02A