Fitxer:Time clocks-1905.jpg

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Time_clocks-1905.jpg ‎(231 × 254 píxels, mida del fitxer: 33 Ko, tipus MIME: image/jpeg)

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Resum

DescripcióTime clocks-1905.jpg	English: Precision pendulum regulator clocks at the United States Naval Observatory in 1905 which generated the time signal sent out at noon every day to all parts of the US by telegraph lines, serving as the primary time standard used to set accurate clocks throughout the US. These two clocks were synchronized to a third precision pendulum clock, the "star clock", which was set by the time of passage of stars overhead. From the source: One of the most important functions of the Naval Observatory is found in the daily distribution of the correct time to every portion of the United States. This is effected by means of telegraphic signals, which are sent out from Washington at noon daily, except Sundays. The original object of this time service was to furnish mariners in the seaboard cities with the means of regulating their chronometers; but, like many another governmental activity, its scope has gradually broadened until it has become of general usefulness. The electrical impulse which goes forth from the Observatory at noon each day, now sets or regulates automatically more than 70,000 clocks located in all parts of the United States, and also serves, in each of the larger cities of the country, to release a time-ball located on some lofty building of central location. The dropping of the time-ball--accompanied, at some points, with the simultaneous firing of a cannon--is the signal for the regulation by hand of hundreds of other clocks and watches in the vicinity. The clocks which contain the mechanism for sending the time signal, cost upwards of $800 each. As a precaution against accident, two of these clocks are provided; but only one is used in sending the signal. At three and a-quarter minutes before noon, the signal clock is switched into the telegraph circuit which covers the entire country; and from that moment until the sending of the signal, all business is suspended throughout the 350,000 miles of telegraph lines over which it is to be flashed.
Data	1905
Font	Scanned from Walden Fawcett, "Distribution of Time Signals", The Technical World magazine, May 1905, p. 24 on https://earlyradiohistory.us website
Autor	DesconegutUnknown author

Llicència

Public domain	Aquest fitxer és en el domini públic en els Estats Units. Això és aplicable a obres dels EUA on el copyright ha expirat, sovint perquè la seva primera publicació va ser abans de l'1 de gener de 1929. Vegeu aquesta pàgina per a més detalls.	United States
	Podria ser que aquesta imatge no estigui en el domini públic fora dels Estats Units (especialment on no s'aplica la regla del termini més curt per obres dels EUA, com Canada, la Xina continental (no a Hong Kong ni Macau), Alemanya, Mèxic i Suïssa). El creador i any de publicació són informació essencial i s'han de proporcionar. Vegeu Viquipèdia:Drets d'autor per a més detalls.

Registre original de càrregues

La pàgina de descripció original era aquí. Els noms d'usuari a continuació es refereixen a en.wikipedia.

2005-05-30 16:37 Ihcoyc 245×289× (13531 bytes) Automatic [[time signal]] clocks in use in [[1905]] to coordinate time with the [[United States Naval Observatory]] by [[telegraphy]]. Scanned from a 1905 magazine, originally published to the Web at http://earlyradiohistory.us/1905tim.htm {{PD}}

Historial del fitxer

Cliqueu una data/hora per veure el fitxer tal com era aleshores.

	Data/hora	Dimensions	Usuari/a	Comentari
actual	23:06, 8 gen 2012	231 × 254 (33 Ko)	Jahoe	Cropped (removed caption text and white borders).
	23:05, 8 gen 2012	231 × 254 (33 Ko)	Jahoe	Cropped (removed caption text and white borders).
	13:44, 20 abr 2009	245 × 289 (13 Ko)	File Upload Bot (Magnus Manske)	{{BotMoveToCommons\|en.wikipedia\|year={{subst:CURRENTYEAR}}\|month={{subst:CURRENTMONTHNAME}}\|day={{subst:CURRENTDAY}}}} {{Information \|Description={{en\|Automatic en:time signal clocks in use in en:1905 to coordinate time with the [[:en:United