Evening star., 1914-12-21

caused to revolve by driving clock
1t is encased in a sheet of paper and a
pen is caused to bear upon the paper
as the cylinder revolvcs. The pen has
an advance motion, so IL left to itself
it would produce a spiral The arm OF
the electro magnet Is attached to the
pen in such way that whenever a
circuit is broken the pen produces a
jog in the spiral The clock is ar
ranged to make jog at every double
beat, so the pen records a regular
series of jogs representing intervals OF
two seconds of time.
The star observer is provided with a
key by which he can break the circuit
when the star is upon successive
threads of the reticle. By SO DOING he
Will have a record on the sheet which
Will represent the time OF the star
transit. AS the right ascension Of tho
star is definitely known, any difference
known to be an error in the clock. A
slight allowance has to be made for
the personality of the observers. One
man may press the key little sooner
or later than another. This fact was
taken into consideration in the series
of simultaneous observations made In
Paris and Washington. which have Just
been computed. The accuracy of the
clocks is secured by continuous tests.
The Naval Observatory has four clocks
which are regarded as practically per-
feet AS changes of temperature tend To
produce slight ina accuracies. three OF
temperature is maintained at 81 degrees
Fahrenheit throughout the year. The
| variance of the temperature OF these
clocks during the past year amounted TO
| only four-tenthS of degree. and the
maximum variation in the accuracy OF
the clocks was only eighteen hundredths
of second during that period.
| Sending out the time signals from the
observatory is an interesting daily Occult
renee. These are
Time Signals sent by the beats ~
Sent at Noon. a transmitting c,9eN
those i'll the vaults in accuracy. The
clock is provided with a toothed v heel
| attached to the seconds pinion. The
| teeth ON the wheel represent seconds
and none is provided for the 10Th, 51th,
56th. 5Ith. 5sth and 59th seconds. When
the teeth revolNe they push spring
opening an electric circuit which sends =
signal along numerous circuits, including
the Western Union and Postal Telegraph
companies and the wireless station at
Airing on. by means of these, each
\ beat of tho clock is recorded in many
places. except The beats for which the
| teeth OF the wheel are omitted This
omission is to enable the one receiving
the message To identify the minutes ami
half minutes.
The signals are sent out each day be-
ginning five minutes before noon. The
| telegraph companies have their wires
cleared for this purpose. In addition TO
the noontme service night signal ser,-
ice has been inaugurated from Arlington
which Is sent out at 800 each night Tile
carrying power uf radio signals is mucn
greater at night than in the day time and
| these signals have been received thou
sands OF miles away. These signals can
be received By anyone who is sufficiently
| interested to erect wireless station TO
receive them. GnG thousands of private
! stations of this kind have been estab-
lishsd IN this country within the past
year. The observatory encourages such
efforts and has recently issued circu-
! lar giving tull directions for esta blishinG
such stations with definite descriptions
/ of the appartt tuS required.
1t is rather interesting TO know that the
! first recorded demand Tor correct time in
or railroad companies, who might be sup
posed to be directly interested. 1t was
made by jeweler, r n. Hershfield Of
Fort LeavenwCrth, Kan. who wrote the
| Naval Observatory in 1876. asking that
some means be devised by which he
could secure correct time by teegra pin
| in order that he might be able to give
| correct local time TO the people OF that
| city. The letter WAS referred to the
Western Union Telegraph Company, with
| the statement that the observa tory would
! if arrangements could be made for
transmitting 1t throughout the country.
The present daily time service has grown
| from this.