Clock Base
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 Antique 1800s Seth Thomas Clock 5981 K Dragon Heads Wood Nice  US $120.00
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 Vintage 1930s United Electric Shelf Mantle Clock The Bartender US $77.78
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 VINTAGE UNITED MANTEL CLOCK MODEL 990 COLONIAL DANCERS US $32.00
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 Vintage Art Deco Veglia Italy Mantle Clock Jewelry Box US $200.00
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 17 inches tall Unique Blacksmith windup Clock held by Blacksmith cast metal US $65.00
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 Marguerite Anniversary Clock by Howard Miller Retired US $.99
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 Cute Handheld clock Time projector watch Easy carry Key chain Interesting EA50 US $.99
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 Art Deco Jefferson Golden Hour Electric CLOCK US $44.95
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 Elvis Presley Anniversary Clock US $5.00
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 HOWARD MILLER BRASS QUARTZ DESK SHELF TABLE CLOCK RUNS GREAT AS IS PENDULUM US $9.99
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 1899 Ingraham Antique Gingerbread Parlor Clock US $74.99
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 LENOX GRANDFATHER CLOCK MINT CONDITION US $10.00
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 Antique Vintage sessions nautical ships wheel electric compass mantle clock US $39.95
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 Seth Thomas Shelf Mantel Clock Parts Or Restore Plymouth Conn USA N R US $42.00
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 New Haven Mantel clock with Gilding fro parts or repair US $62.95
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 Leroy French Carriage Clock US $260.00
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 VINTAGE LATE 50S EARLY 60S SESSIONS CEREMAC ELECTRIC CLOCK US $24.99
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 Fine Schatz German Anniversary Clock Floral Face with Dome US $25.00
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 Vintage Metal Horse United Self Starting Clock w Wood Base US $37.00
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 Vintage Westclox Big Ben Alarm Clock Illuminated Glow in Dark Hands Green Face US $9.99
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 VINTAGE BRONZE TONE METAL DECORATIVE MANTEL SHELF QUARTZ CLOCK INDIA US $19.99
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 ANTIQUE FIGARO ENAMEL AND MARBLE BASE ALARM CLOCK US $29.99
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 Vintage WALTHAM Art Deco Clock w Chrome Stepped Base 8 Days US $52.33
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 2009 sandra kuck collection anniversary clock w westminster chime garden angel US $20.00
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 Vintage Square Brass Clock Desk Table Quartz AA Battery US $35.00
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 WEDGWOOD JASPERWARE CLOCK CASE CHERUBS US $9.00
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 Franklin Mint Royal Geographical Society World Globe Clock working US $700.00
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 1 ELGIN QUARTZ BATTERY OPERATED ANNIVERSARY CLOCK WITH GLASS DOME US $10.95
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 VINTAGE BRASS HORSE SHELF MANTEL CLOCK UNITED CORP US $59.00
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 VINTAGE BRONZE HORSE SHELF MANTEL CLOCK SESSIONS US $79.00
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 STRANGE DIFFERENT BRONZE ART DECO DESK CLOCK CHEMO COMPANY ADVERTISING Doctor US $24.99
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 S Haller Simonswald W Germany ANNIVERSARY Globe MANTEL CLOCK 11 tall glass US $19.99
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 New haven Minature CatlinDeco ClockLook US $40.00
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 Vintage LUX MANTLE CLOCK from 1930s works and keeps time US $24.50
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 ANTIQUE RARE 1720 JEAN FRANC DUCHESNE FUSEE BEDROOM CLOCK US $199.00
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 CHARMING VINTAGE EMES TIN LTIHOGRAPH CLOCK MUSIC BOX USED SWISS MOVEMENT US $20.49
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 EARLY 20TH CNTY ROCOCO STYLED MANTLE CLOCK WORKS COURTING CHILDREN SWANS US $9.99
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 BARBIE PENDULUM GLASS DOME CLOCK US $1.99
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 8 DAY WORLD SMALLEST MINI CONGREVE ROLLING BALL CLOCK with Rosewood Base US $850.00
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 Antique WESTINGHOUSE Shelf Mantel Clock for Parts or Repair US $14.99
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 Elvis Porcelain Base Anniversary Clock NEW IN THE BOX US $15.00
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 Animated Kitten With Fish Bowl Clock Lots of Movement US $26.00
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 Howard Miller Anniversary Clock Not Working US $149.99
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 Army Symbol Eagle clock in wood base US $3.99
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 Antique 8 Brass Clock Face and Movement Made in England Unknown Vintage US $19.99
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 White Kitchenaid Stand Mixer Mini Clock with Beaters Bowl Handle Details US $15.50
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 German Magneto Mechanical TORSION Clock ALBION US $110.00
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 VERY NICE WOOD CLOCK FROM INDIA SHELF MANTLE CLOCK US $22.99
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 ANTIQUE 1936 GLOBE PENDULUM CLOCK CHICAGO WORLDS FAIR US $45.00 |
 Antique Waterbury Beehive Mantel Clock US $95.00
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 Small Desk clock by Charles Elkan made of Maple Burl NEW US $15.00
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 Vintage CLINTON RADIUM clock brass base works WEST GERMANY w original box US $8.00
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 Skeleton Decorative clock Brand New NIB contemporary stainless steel watch US $67.99
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 VINTAGE DESKTOP LOOPING 15 JEWELS 8 DAYS ALARM CLOCK RARE EXCELLENT CONDITION US $51.00
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 VINTAGE KUNDO KIENINGER OBERGFELL ANNIVERSARY CLOCK W KEY WORKS US $25.49
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 Antique Ansonia Ornate Gilt Victorian Carriage Clock US $350.95
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 CLOCK WITH HORSE United metal goods mfg co incfrom Brooklyn NY US $122.50
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 Antique German Mantle Clock US $100.00
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 Oak Wall Clock Case Empty Case305 x 11 x 6 US $13.15
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 FLOWER PEDISTAL CLOCK RICHARD RAU WEST GERMANY VINTAGE US $9.99
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 old haller 400 day anniversary clock for repair US $8.99
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 VINTAGE ANNIVERSARY CLOCK DOME COVER GLASS 8 TALL DOME ONLY PART 4 BASE US $14.99
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 HOLLAND MOLD Ceramic Mantle Clock Clock Movement by Lanshire US $39.99
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 6 Jewel Kundo ATO Clock w Glass Dome NR US $99.50
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 Vintage 1930s Sunbeam Eternatime Electric Clock with Onyx Base US $99.00
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 Boxed Moorcroft Limited Edition Mantel Clock Magnolia Pattern 75 94 US $452.25
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 Gilbert Mantle Clock 4384 US $15.00
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 Michael Graves For Target Art Deco Modern Alarm Clock US $6.99
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 Jennings Brothers Vintage Metal Art Nouveau Desk Clock US $14.50
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 Vintage Sessions Mantel Clock US $25.55
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 Vintage Seth Thomas Chime Clock Model E525 000 Sharon Echo S Pristine Condition US $49.95
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 VINTAGE CHARMING THE VILLAGE MILL WINDUP CLOCK A SYROCO FINISH WATER MILL US $60.00
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 Original Kieninger Grandfather Clock Movement 4 72 RK 93cm NOS No Jewels US $29.00
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 Hermle Black Forest Grandfather Clock Movement 451 030 66 cm 80166 NOS 5 Chime US $19.00
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 Grandfather Clock 8 Chimes Parts Westminster NOS Kieninger Hermle US $15.00
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 BIG LOT 6 Miniature Clocks Mantle Carriage White Gold Platinum Callezio more US $50.00
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 Vintage Schatz 400 Day Clock Anniversary Clock Brass Pendulum Clock US $20.50
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 RARE VINTAGE WESTWOOD 8 DAY CLOCK missing base US $50.00
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 Vintage Alarm Clock Marble Base Made in Germany US $9.99
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 Brass Marble Clock US $30.00
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Atomic Clocks: History and Development
Atomic clocks have been with us for over fifty years now and most people have heard of them and know they are very accurate, but how accurate are they and why do we need such accurate clocks?
Atomic clocks are used by many of us even if we are not aware of it. The time they tell is relayed around the world and picked up by time servers using the protocol NTP to synchronise networks, they are vital for lots of technologies, such as global satellite navigation, and TV signal timings.
Before the development of the atomic clock the most precise timekeeping devices were electronic clocks which would lose a second or two every week. These had largely replaced mechanical clocks which were less accurate still.
Mankind has always had a fascination for keeping track of the time but knowing the precise time has never been too important. A second or even a minute’s difference does not affect our day-to-day lives.
However, as technology has advanced the need for more precise timekeeping has increased. Satellites that have to be navigated and communicate with the Earth from hundred, thousands and even millions of miles away require exact timing. Light and therefore radio waves can travel 300,000 km every second so slight inaccuracies in time can have massive differences.
The first accurate atomic clock was built y Britain’s National Physical Laboratory in 1955 by Dr Louis Essen who based his clock around the oscillation of the caesium -133 atom. The idea was actually first conceived as far back as 1879 when Lord Kelvin proposed that time-keeping based on how atoms behaved would be a better way to count time intervals than anything else.
The first generation of atomic clocks (also known as caesium oscillators) used the frequency of this atom which oscillates 9,192,631,770 times every second. Essen’s model was accurate to a second every 300 years but developments of the caesium oscillator mean they can now achieve accuracies of one second every 80 million years.
Yet as technologies get more advanced, scientists strive to make better and more accurate clocks. Rubidium standard clocks offer no better accuracy than caesium models but are smaller and cost less (caesium oscillators are generally only to be found in large-scale physics laboratories).
Clocks using just a single atom have been developed that offer even more accuracy. A clock based on a single mercury atom has achieved accuracies of one second in 400 million years and it is expected that a new type of strontium clock that uses light will go even better.
The future for atomic clocks is ever increasing accuracy combined with scaling down the size and cost of them. The American National Institute of Standards and Technology (NIST) have unveiled a chip-sized atomic clock that boasts millisecond accuracy.
Atomic clocks are now part and parcel of our lives without the time signals they transmit to the world that are picked up by NTP servers modern communication from Internet shopping and GPS and technological advances such as satellite navigation would become impossible.
About the Author
Richard N Williams is a technical author and specialist in atomic clocks, telecommunications, NTP and network time synchronisation helping to develop dedicated NTP clocks. Please visit us for more information about atomic clocks or other network time server solutions.
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