The Carbon County news. [volume] (Red Lodge, Mont.) 1924-1931, 1930-09-18
HOW UNCLE SAM
KEEPS GOOD TIME

The proposal to give a niche in
the hall of fame to Charles Fer
dinand Dowd, the man who origin
ated the idea of Standard Time,
again recalls to mind the tremen-
dous improvement in our time
standards during the past gem
Grafton, and the great pains to
which Uncle Sam goes to give his
people the correct time. The I'm
tied States Naval Observatory at
Washington has this important
function to perform, and it does
the task vel. In an interesting ar
ticle in the current issue of the
National Republic on keeping
Time for Uncle SAM Mr.. Han
cock Adams says, in part:
1.-THE Naval Observatory boasts
three standard clocks. These are
maintained in an underground va
ult under uniform temperature and
air pressure. These clocks keep ST.
dereal, or star time. 1t is most
important that they be never dis
turbed. Except for repairs, which
are carried out by experts train
ed to handle their delicate mec-
hanism, they are never reset or
interferred with. These clocks are
rather extraordinary instruments.
They have invar pendulum rods
which do not change in length on
account of temperature variation.
They have, too, rather unusual
form of escapement, in which no.
thing touches the pendulum rod
directly, and the driving impulse
is impaired through the pendulum
suspension rings.
1t is interesting to note that
these clocks generally tend to run
faster as time passes. During the
first year after cleaning, their
daily rates tend to increase at the
rate of hundredth of a second
per month, but after that they run
at a more constant rate.We must
bear in mind that the actual rate
of the clock is not so important,
as long as it is steady and as long
as the actual changes are small
enough to be checked up by astro-
nomical observations. 1t is the sud
den variation that lessons the use
fitness of time piece. The short
period variations in the rate of the
standard clocks are such on the
average that they can be predicted
within abut a hundredth of a sec
ond day. That assuredly is a
small enough error to satisfy any
commutor, even the most exacting.
what is the basis of time mea-
surement? While the earth is in
rotation, the stars appear to rise
in the east and to set in the west,
just as does the sun. The only
difference is that the stars seem
to make one trip around the sky
in almost the true period of the
earth's rotation, while little bet
ter than one revolution of the
earth is needed to bring the sun
again to the same apparent posi-
ton. The reason for this is that
the earth's orbital motion around
the sun constantly changes the
apparent place of Old Sol among
the stars. Even if the earth did
not revolve at all on its own axis,
the sun would rise and set once
during the year for the simple
reason that the earth journeys a
round it. The stars of course do
not lie within the earth's orbit.
AS matter of fact, they are SO
very far off that their apparent
positions are only slightly affect
ed by the earth's orbital revolu-
tons. Astronomers designate one
sidereal day the period of the
earth's rotation measured in re-
ference to : point in the sky
known as the rernal equinox. Tt
is IN This rotation period that we
find tie most convenient and
standard Of time measurement.