| |
KF5JRV > TECH 02.06.16 12:36l 48 Lines 2490 Bytes #-3522 (0) @ WW
BID : 3867_KF5JRV
Read: DK3UZ GUEST OE7FMI
Subj: Sheppard Gate Clock
Path: DB0FHN<OE2XZR<OE5XBL<F1OYP<IZ3LSV<IR1UAW<IQ5KG<I0OJJ<N6RME<N0KFQ<
KF5JRV
Sent: 160602/1124Z 3867@KF5JRV.#NWAR.AR.USA.NA BPQ1.4.65
>From kf5jrv%kf5jrv.#nwar.ar.usa.na@i0ojj.ampr.org Thu Jun 2 13:30:11 2016
Received: from i0ojj.ampr.org by i0ojj.ampr.org (JNOS2.0j.7v) with SMTP
id AA229180 ; Thu, 02 Jun 2016 13:30:11 +0200
Message-Id: <3867_kf5jrv@n6rme.bbs>
>From: kf5jrv@kf5jrv.#nwar.ar.usa.na
X-JNOS-User-Port: Telnet (n6rme @ 44.134.32.240) -> Sending message
The Shepherd Gate Clock, Greenwich, London, England
Perhaps one of the most significant timepieces in the world, the Shepherd Gate
Clock is mounted on the wall outside the Royal Greenwich Observatory, the home
to the Greenwich Meridian Line, marking the Prime Meridian of the World at 0
(zero) degrees longitude. All other locations on Earth are measured using this
line as a reference point. Installed in 1852, the clock is controlled by a
master clock inside the building
The master clock, at first called the Normal Clock or Master Clock, but later
known as the Mean Solar Standard Clock, sent pulses every second to the
sympathetic or slave clocks in the Chronometer Room and the Dwelling House (
Flamsteed House) and to the Gate Clock. A pulse was also sent to the time ball
at 13:00. The signals were also transmitted along cables from Greenwich to
London Bridge. At London Bridge, a time signal was distributed at less
frequent intervals to clocks and receivers throughout England.
Airy's report to the Observatory's Board of Visitors in 1853 explained the
function of the Shepherd master clock:
This clock keeps in motion a sympathetic galvanic clock in the Chronometer
room, which, therefore, is sensibly correct; and thus the chronometers are
compared with a clock which requires no numerical correction.
The same Normal Clock maintains in sympathetic movement the large clock at
the entrance-gate, two other clocks in the Observatory, and a clock at the
London Bridge Terminus of the South-Eastern Railway.
It sends galvanic signals every day along all the principal railways
diverging from London. It drops the Greenwich Ball and the Ball on the
Offices of the Eastern Telegraph Company in the Strand.
All these various effects are produced without sensible error of time; and
I cannot but feel a satisfaction in thinking that the Royal Observatory is
thus quietly contributing to the punctuality of business through a large
portion of this busy country.
By 1866, time signals were being sent to Harvard University in Massachutis via
transatlantic cable
Read previous mail | Read next mail
| |
