The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-05-14
GREENwIcHs GREAT CLOCK.
The Constant Care Involved I'm OBJ
tanning the Correct Time.

From the New York Commercial Adver-
tlser.
About four miles from London, in the
County of Kent, is the parliamentary bor-
ough of Greenwich. The census folk give
it. a population of about 10000. but 1t has
none of the bustling activity of an Ameri-
can city of the same size. Yet, it has its
share of fame. but not as great to a por-
tion as It should have considering that it
enters into the minute affairs of every
man, woman and child in the civilized
world This is a pretty broad statement.
but it is the truth, as will speedily be
shown.
Ask any resident of Greenwich to point
out the most prominent feature of ;he
town. and it is ten to one that he will in
dictate the historic Greenwich hospital.
Ask him about the second most important
feature, and, If he be particularly shrewd.
he may say the royal observatory Lo-
cally, the hospital is a thing of tremen-
dous importance, while the observatory
is seldom thought Of
While much time is given to the study
Of the moon and other planets, the main
business of the observatory is to secure
the correct time. To detail all of the
labor regarding the latter would be an
endless task, and a dry one to the reader.
so merely an outline will be given. The
mean time standard clock, which gives The
time of day TO the world, is connected by
electric action with the mean solar clock,
and Is further kept correct by calculation
and comparison with the standard slider
eral clock, whose error is determined by
observations of the stars. The sldereal
clock is considered the most wonderful
a ar Fala .N.as4n Ia
marvellous instrument is in an undor-
ground room. called the magnetic base
ment, where 1t stands like a sentinel, with
its back against the wall ticking its seq
onds as prescribed by the "clock stars"
This reference to the "clock stars
fixed stars, slightly over 200 In number,
which are used for determining sidereal
most important instrument in the obserY-
atory, and one of the most interesting,
1t consists of large telescope the outside
of which is not unlike a great common, as
II is of solid iron. This instrument Is sup
ported by trunnions which allow the tele-
scope to be elevated or depressed. TO point
north or south. and. In fact to make a
complete revolution, but never TO diverge
from the north and south line. The mag
nifying power of this Instrument Is not
very great, but It's field OF view is large,
so that II admits plenty Of light, for IL is
gazing at celestial objects, but for noting
the exact time at which stars and planets
pass south and north Of Greenwich.
Upon looking through this telescope the
observers eye is first attracted by "A verti-
cal row OF what seems to be iron bars,
placed at equal distances from each other.
They are, however neither more nor less
than spiders webs-the center one passing
through the focus of the object glass, be-
ing the meridian line. BY observing the
time at which the "clock stars' pass over
these web lines. or wires" as they are
called, Is sidereal time regulated The adj
justment of the instrument has to be ex-
tremely exact in order to obviate error.
The slightest thing will put IL out-even
so small a matter as too much sunshine.
on one occasion the correction for a level
error in the instrument having become in
conveniently large, owing apparently TO a
subsistence of the eastern support, about
ton-weight of stones was placed on the
western pier
But this having no effect the stones
were removed and a sheet OF very thin
paper was placed under the support on the
eastern side by which means the error
was corrected. This will give some idea
of the delicacy Of adjustment necessary
for the perfect working Of the ponderous
instrument.
The hands of the sldereal clock are said
to be at zero when the first point OF the
constellation of Aries, or that point OF
where the ecllptic and equator cross. Is
on the meridian, and, II the clock does
not vary In time, It's hands will indicate
exactly the rate Of diurnal motion OF the
heavens. Every degree of the equator will
mark four minutes of time, and every Is
degrees Will mark one hour, and so on, In
proportion with the twenty-foiir hours
and the $50 degrees of the great circle.
An astronomical clock will beat S. 400
seconds In twenty-four hours when going
TO it's utmost exactitude, but, as no me-
chanism Is absolutely perfect a may be
either a second under or a second over this
number. and II rs this variation which
the astronomer has TO discover and al
low for.
All the chronometers used IN the British
navy are first tested IN the observatory
the test lasting eight months. From
January TO August are the best months
for making the tests. Those Intended Tor
use In the tropics are placed for weeks
az a time IN ovens heated by gas, and
II takes a frst-class chronometer 10 with
stand this ordeal
Prior TO 1888 each country had its own
meridian Of time-France al Paris. the
United States at Washington, ana Inc
others az their capitals. This led 10 10
rlous differences IN navigation. and com.
promise was effected by which the Croon.
wich meridian was settled upon. with mi.
form allowances for the distances OF vari.
Gus countries.
THERE Is LIFE IN CRYSTALS