Evening star., 1925-09-20

over the telephone IN
Washington. requires the
services of scores Of telegraph and
telephone operators. several scientists.
nd not a few mathematicians. using
the knowledge of the ages as applied
through the most accurate machinery
man can devise to answer rightly.
Residents Of the Capital City. who
indulge in pardonable civic pride when
they reflect upon the many features
OF this community which make it. in
all reality. the Nations home city
are further pleased whenever it is
brought to their attention that Amer
lea comes to Washington for it's time.
Best Of ALL it does not come in vain.
Out near Massachusetts, Avenue Park.
| under the dome capped buildings OF
the United States Naval Observatory,
are instruments which keep time with
a degree Of accuracy that can scarcely
be appreciated by the average person.
When q man possesses a watch which
varies only a few seconds a week. he
regards 1t as pretty good" time
piece, but at the Naval Observatory
there Is q standard clock whose rats
has varied less than a tenth of sec
ond during the past two years.
Such hair-line precision is unneces.
sary to the man on the street. but Tor
the scientist it is essential. 1t VIII be
recalled that. in spite OF the use OF
instruments of this kind, the astron.
omers' calculations as to the time OF
the solar eclipse of last January were
fve seconds wrong. Such small err
ror appears almost ludicrous to most
of us, but 1t was regarded as i'm.
mensely important by many experts,
who know that IL the cause fof a mis-
calculation of this sort liz learned
there Ia q possibility that It may lead
to the discovery OF hitherto un'
known scientific principle.
But while some Of the best brains
| in the astronomical world y solving
the mystery Of those five seconds land
two of them have been accounted forl
YOU and I will remain fully satisfied
with the time service as at present
| furnished us by the all-hut-perfect
sta ndard clocks at our Naval Observa
| tory.
There are three OF them. and they
are kept in an even temperature vault
below the observatory buildings. They
rest on solid piers in order to elm
mate any errors that might result
from ordinary earth tremors. Air cur
, rents are avoided in the vault by q
system Of double doors: the outer
entrance being close before the inner
| into the chamber.
To insure further accuracy each
! clock is kept In sealed glass
| cylinder. For purposes Of regulating
| the rate of the clock the air pressure
| in the cylinder is reduced. The
pendulums are of 'Invar' or nickel
steel. a metal which Is little in
! fiuenced by changes of temperature.
They certainly are not subject to
much variation, for Thermometers In
side the glass cases show that the
temperature there varies scarcely
| one-tenth of degree Fahrenheit in
| a year. The clocks are rewound elac-
| trically every halfminute SO that no
adjustment of pendulum 10 necessary.
The face of the standard clock Is
quite different from that OF our com
mon timepiece. The large pointer Is
the minute hand, while the small
! lower one is the hour hand and the
one above that the second hand.
| The hour dial is numbered l to "a,
eliminating the extra exertion neces.
sary to keep track of our cumber-
! some am. and pm. system.
The slight errors of these clocks
are ascertained through observation
Of certain hxed stars called o'clock
stars" Every night. when weather
conditions are clear enough to permit
such observations. they are made at
the observatory by means OF tele-
scopes trained on the meridian and
equipped with devices which deter
mine exactly the time of the transit
of the stars.
Having thus learned the exact"
time, the observatory makes it part
Of its business to broadcast this es-
sential information by telegraph and
radio to all parts Of the country and
across the high seas.
As every radio fan knows. wireless
time signals are transmitted at moan
ana 10 pm. That long series q
buses followed by ths intriguing