Relógio do Cais do Sodré - Lisboa, Portugal
Posted by: manchanegra
N 38° 42.372 W 009° 08.586
29S E 487557 N 4284183
This is the clock that sets the Official Time in Portugal.
Waymark Code: WMD1A8
Location: Lisboa, Portugal
Date Posted: 11/05/2011
Views: 9
This clock has been (and still is) very important to the life of the city because he his marking the offial time in Portugal for almost a century.
The official time in Portugal is set by the Observatório Astronómico de Lisboa (OAL)/ Lisbon Astronomical Observatory .
Before the existence of radio signal and the current Global Positioning System (GPS), the vessels departing from Lisbon port needed to set their watches with the right time, in land so that when at sea they could accurately calculate their longitude.
In order to issue the official time for the city and in particular for ships anchored in the Tagus River, a sentry box was built in 1914, in Cais do Sodre area. This sentry box was equipped with a mechanical clock connected by a cord to the OAL in Tapada da Ajuda. From that sentry box a signal was sent to a semaphore in Belem from where a ligh signal would indicate the right time to the ships anchored in the Tagus river.
In 2009, a quartz clock was installed in Cais do Sodré, connected tothe OAL atomic clocks via NTP system ("Network Time Protocol"), ensuring the accuracy of clock time.
This quartz clock was sponsored by Tissot and the dial is the reproduction of a Tissot watch. The dial clock is very acurate and the dial represents in roman numerals the hours, in arabic numerals the minutes and vith small traces, the seconds.
On the lower part of the dial it´s writen Escudo, the ancient Portuguese currency.
Status: Working
Display: Mounted
Year built: 01/01/1914
Web link to additional info: Not listed
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Photo of clock.