For some scientific work timing of the utmost accuracy is essential. It is also necessary to have a standard of the maximum accuracy against which working clocks can be calibrated. An ideal clock would give the time to unlimited accuracy, but this is not realisable. Many physical processes, in particular including some transitions between atomic energy levels, occur at exceedingly stable frequency; counting cycles of such a process can give a very accurate and consistent time—clocks which work this way are usually called atomic clocks. Such clocks are typically large, very expensive, require a controlled environment, and are far more accurate than required for most purposes; they are typically used in a standards laboratory.
Tired of the same old clock hanging on your wall? Is the incessant ticking of the time a constant reminder you need to change it out? Purchase a new wall clock from our great selection. All of Zazzle's wall clock designs are printed in full color, so the design you choose will look vibrant for a long time. Not only can you choose from our great designs, you can also pick whether you want a round, square, or aqua clock to help keep track of time. Browse through the collection to find a clock you'll love every second and every minute!
Until advances in the late twentieth century, navigation depended on the ability to measure latitude and longitude. Latitude can be determined through celestial navigation; the measurement of longitude requires accurate knowledge of time. This need was a major motivation for the development of accurate mechanical clocks. John Harrison created the first highly accurate marine chronometer in the mid-18th century. The Noon gun in Cape Town still fires an accurate signal to allow ships to check their chronometers. Many buildings near major ports used to have (some still do) a large ball mounted on a tower or mast arranged to drop at a pre-determined time, for the same purpose. While satellite navigation systems such as the Global Positioning System (GPS) require unprecedentedly accurate knowledge of time, this is supplied by equipment on the satellites; vehicles no longer need timekeeping equipment.
A brushed and polished brass finish gives this metal carriage alarm clock its enduring style. The decorative handle, turned brass button feet, and polished brass-tone columns at the corners add to the clock's stately presence. Beneath a glass crystal, the brushed brass-tone dial features circular, diamond-cut numeral ring, black Roman numerals, black hour and minute hands, and brass second and alarm hands.
Now this is an alarm clock for the heaviest sleeper. If you're the type who sleeps through anything — thunderstorms, loud neighbors, earthquakes, the zombie apocalypse — you've finally met your match. Sonic Alert's Sonic Bomb Alarm Clock doesn't just rely on its 113-decibel alarm to pry your eyelids open (for comparison, that's about the same decibel level as a car horn or snow blower going off in your ear), it also has a shaker device that slips underneath your mattress or pillow to jiggle you awake, and red flashing lights that trigger with the alarm.
Sounds like a Marvel villain if you say it out loud, doesn’t it? Sonic Alert Vibrating Skull Crusher Clock has a bit of edge to it, and like your metal days, it’s going to wake you up with a thunderous roar. You get 113 decibels of noise, which is basically like a crappy $20.00 blender whizzing right next to your head. Hook up your phone or MP3 player to rock out to your tunes in the morning, should you dare. You get a five-dimmer setting for the red LED display, and the 12-volt bone crusher bed shaker, just to make sure you’re really awake in the morning.
Need a little extra incentive to pry yourself out of bed? You'll have plenty of it with this no-nonsense wheeled alarm clock. After the first time you press snooze, this unit automatically starts moving away from you, creating enough distance to literally force you out of bed in order to shut it off for good. Plus, it also comes in pastel blue, white, red, and more.
A perfect piece for nightstands and home office desks, this radio alarm clock tunes to your favorite stations as it keeps an eye on the hour. Its bright red LED numbers are easy to read from afar, while the repeating nine-minute snooze is sure to become your new best friend on lazy Sunday mornings. This digital clock includes memory for up to 20 radio stations and includes an audio input for smartphones and MP3 players. Though this radio plugs into your wall, it also runs on two AAA batteries...
No, that’s not a statement - it’s an app title. This little handy dandy game makes you solve puzzles or finish writing exercises before it’ll let you off the hook. If you try to snooze it too many times, it’s going to remember, and put you through hell. It’s like getting interest on the fact that you slept in an extra five minutes the day before. For the love of gear, just solve the puzzle, and muddle through the morning - you’ll be glad you did.
Designed to fit anywhere in your home, the Amazon Echo Spot uses voice recognition to let you see weather forecasts, read music lyrics, listen to Audible audiobooks, and more — and it’s all hands-free. Just ask Alexa to snooze the alarm. You can even ask Alexa to control the smart home devices in your house, including lights, locks, cameras, and thermostats. Need to make a phone call and don’t want to walk across the room to your phone? Ask the Spot to make phone calls or video calls to family and friends. As you can see, the Spot has much more in common with the Echo Dot than with a traditional alarm clock, although you’ll still get the time and a sleep mode. For more, read our full review.
A clock that looks good and runs smoothly instantly adds charm and functionality to your living space. For a fresh take on the traditional wall clock, consider this eye-catching design. Introducing Ribbon Wall Clock by Umbra Add a modern, minimalist twist to telling time. With Ribbon, you get a stylish piece of wall décor and a functional wall clock all-in-one. Made with high-quality metal that’s been shaped to resemble overlapping ribbons, this unique clock features contrasting hands...

Add a dash of visual intrigue and stylish sophistication to your ensemble with this eye-catching wall clock, the perfect piece for your well-curated aesthetic. Hang it up on a deep blue or charcoal-toned wall in the living room to complement its shimmering silver finish and hard-lined metal design, then offset its striking starburst silhouette by arranging a console table below with glossy ceramic vases and simple metal picture frames. Curating a midcentury-modern aesthetic in your space? Lean...


This farmhouse wall clock measures 30 in. across This farmhouse wall clock measures 30 in. across the face and features horizontal cedar wood slats a white distressed finish hand painted black Roman numerals in a Poster Condensed font and an inner accent ring with individual hour marks. It includes a high torque quartz movement antique-style spade hands and ...  More + Product Details Close

Besides the Chinese astronomical clock of Su Song in 1088 mentioned above, in Europe there were the clocks constructed by Richard of Wallingford in St Albans by 1336, and by Giovanni de Dondi in Padua from 1348 to 1364. They no longer exist, but detailed descriptions of their design and construction survive,[22][23] and modern reproductions have been made.[23] They illustrate how quickly the theory of the mechanical clock had been translated into practical constructions, and also that one of the many impulses to their development had been the desire of astronomers to investigate celestial phenomena.
The Howard Miller 625-542 Brass Works is an oversized, large wall clock featuring a metal outer frame finished in antique brass and accented by four decorative antique brass finished screws applied to the dial. The dial features antique brass-finished gears viewed through an open center. The gear in the middle of the clock turns as a second hand would rotate.. Quartz, battery-operated movement requires 1 AA battery. One year warranty and Free Shipping.
Remember a time before everything was digital? Yeah… we don’t either. But a few excellent time-tested products pop up out of the woodwork from time to time, and a traditional dual bell alarm clock does the trick. The hands move silently while you sleep, and buzz like a mother when it’s time to rise and shine. If you’re like us, you’re sometimes bothered by LED flashing you in the face all night. With Peakeep Twin Bell Stereoscopic Clock, you simply touch the button to activate the stereoscopic dial backlight, check the time, and they cop-out for another fifteen minutes. Don’t worry – Peakeep will wake you up.
Antique styling in a two-tone wall clock features a Worn Black finish with red undertones and a contrasting Antique Red inset panel. Beneath a convex glass crystal, the dial features an Antique Red background with gold Arabic numerals and aged brass-tone spade hands. The wood stick pendulum features a spun brass-finished bob. Finished in Worn Black on select materials, hardwoods and veneers. Quartz, non-chiming battery operated movement.
But where OK to Wake! really shines (pun intended) is in its unique feature that parents love; the clock will glow green and show a cute face when it's an acceptable time for your little one to get out of bed. That means even very young children can learn when it's okay to go looking for mommy or daddy — no need to be able to actually read the time. As your child grows, you can stop using the glow feature, and simply use the device as a regular, albeit cuter than average, alarm clock.
A piece of art and a functional home essential – this wall clock is a lovely addition to any home. Inspired by contemporary designs, it showcases an open frame crafted from metal wire. The geometric pattern will stand out against any color wall, while the golden finish adds a pop of glamorous appeal. At the center is a golden disk with two sleek black hands. This wall clock requires two AA batteries (not included).

Small in size but striking in style, this eye-catching wall clock brings a dash of contemporary flair to any arrangement in your home. Showcasing a sunburst silhouette measuring 20" in diameter, this round silver-finished design is crafted with an iron and mirrored frame comprised of black spokes with orb-like accents. A petite glass clock face with sword-style hands sits in the center, allowing you to keep an eye on the hour in any room.
Brimming with an antiqued appeal, this clean-lined wood and glass wall clock brings function and flair to your home. Its distressed details pair perfectly with reclaimed teak wood accents while its neutral color palettes blend effortlessly into any monochromatic look. Add this piece to the den to bring the traditional flair to a cozy coastal arrangement, then pair it with woven rattan furniture and driftwood decor for a complementing look. Round out the room with a hand-woven jute rug to define...

A: From personal experience, a firsthand account of an insomniac, if you will, Sleep Sense really did the trick. There’s a million reasons why you might not be sleeping, and while most of the time it’s stress or something of the sort, it could also be a deficiency of certain vitamins and minerals. Sleep Sense comes with melatonin, magnesium, and other ingredients, all designed to help you sleep, without the fear of becoming addicted or dependent on them. It took about three years to get over insomnia (if the TV is on, I still can’t sleep), but after enough trial and error, and a good dose of Sleep Sense, it did the trick. I stopped dreading the alarm clock so much.

Howard Miller Carmen wrought iron wall clock with cast decorative corner ornaments finished in warm gray, dusty wax highlights. Windsor Cherry finished wood columns provide a warm accent on each side. Convex glass covers the antique dial, which offers black Roman numerals and serpentine hands. The swinging pendulum is finished in warm gray with dusty wax highlights to match the case. Quartz, non-chiming battery operated movement.

You don't have to use all of those features, however. You can set them in a variety of combinations, or even turn all of them off except for the flashing red lights. You can also set the length of the alarm's ring from one to 60 minutes, and choose a snooze option from one to 30 minutes. Plus, the clock has dual alarms, so both you and your partner can have different wake-up times.


Showcasing the time, date, and weather, this clock is an essential for any desk. No need to lift your arm and look at your watch or light up your phone screen, this 0.3'' H x 3.7'' W x 1.5'' D design is an easy way to get the info you need. A vibrant blue backlight keeps it illuminated (requiring the power of a AA battery), while a plastic frame allows it to stand upright.
This curvaceous wall clock features carved accents and a turned urn finial which complement the unique style. The aged dial offers black Roman numerals and decorative black hands. A special 80th Anniversary Edition. The wooden stick swinging pendulum features an antique-brass spun bob. Finished in Tuscany Cherry on select hardwoods and veneers. Quartz, dual chime movement plays switchable quarter hour 4/4 Westminster or Ave Maria chimes. Volume control and automatic nighttime chime shut-off option.

More than just a tool for keeping track of the time, this eye-catching wall clock helps turn any empty wall into an artful display. Crafted from injection plastic finished in a sleek metallic tone, it features a circular center with rods all around extending to stage the numbers of an analog dial. Measuring 16'' in diameter, it makes a statement on your kitchen or entryway wall without dominating the decor.
The British had predominated in watch manufacture for much of the 17th and 18th centuries, but maintained a system of production that was geared towards high quality products for the elite.[44] Although there was an attempt to modernise clock manufacture with mass production techniques and the application of duplicating tools and machinery by the British Watch Company in 1843, it was in the United States that this system took off. In 1816, Eli Terry and some other Connecticut clockmakers developed a way of mass-producing clocks by using interchangeable parts.[45] Aaron Lufkin Dennison started a factory in 1851 in Massachusetts that also used interchangeable parts, and by 1861 was running a successful enterprise incorporated as the Waltham Watch Company.[46][47]
Wall clocks offer a decorative alternative to traditional wall art while also serving a practical function. Whether you want an oversized wall clock to mount above the fireplace and serve as a focal point in your living room or a small model to hang in your kitchen to help keep your family on schedule on school days, Overstock carries the perfect model for your needs. Trusted brands, including Westclox, La Crosse, and Hans Andersen Home, ensure accuracy and durability. From retro-inspired metal clocks in colorful finishes to classic wooden case clocks featuring lustrous stains, Overstock carries wall clocks in an array of styles, sizes, and types with a wide range of features. Read on to learn more about the inventory of wall clocks at Overstock.

The Howard Miller Arendal II 625-551 Wall Clock is a long version of the ever popular Arendal Quartz Wall Clock. This tall, elongated 49" high wall clock features carved accents and a turned urn finial which complement the unique style. The aged dial offers black Roman numerals and decorative black hands. The long, wooden stick pendulum features an antique-brass spun bob which swings back and forth and is battery operated like all quartz clocks. The wooden stick swinging pendulum features an antique-brass spun bob. Quartz, triple-chime Harmonic movement plays choice of full Westminster or Ave Maria chimes with strike on the hour with 1/4, 1/2, 3/4 chimes accordingly or switch to hourly only. Bim Bam chime on the hour only. One year warranty and Free Shipping.
Now, RCA Digital Alarm Clock is pretty basic, but for some of us, that’s all we need, right? With a bright, beaming red LED display, you’re certain to rub your eyes and wonder what weird light is pulsating from your nightstand. There’s an alarm indicator and the classic AM/PM light that we all remember from early-2000 models. You can do something different from your late 1990s-inspired clock, and that is change the brightness levels so you don’t completely burn out your retinas.

Howard Miller 625-613 Company Time II Large Wall Clock is a 34" wall clock with an antique nickel frame. The center dial is a bubbled panel that is heavily distressed and deeply dented for an aged appearance. The individual off-white number panels are curved and dented with Black Roman numerals centered on each panel. The accurate quartz movement requires one "AA" battery. Always measure your area to make sure the wall you have will accommodate this large of clock. One Year Warranty and Free Shipping.
For light sleepers, audio alarms can be rather jarring. Fortunately, the Philips Morning Wake-Up Light uses a warm, gentle glow and natural sound effects rather than incessant beeping to get you out of bed. The alarm clock also features a colored sunrise simulation and 20 brightness settings for optimal customization. The light slowly increases in brightness between 20 and 40 minutes prior to your desired alarm time. The clock helps you drift to sleep, too. Instead of you simply turning out the lights and settling into bed, the light-responsive dimming feature gently guides you to sleep with audio accompaniment. This type of alarm is definitely not for everyone, but it is suitable for those who prefer to wake up gradually. For more details, read our full Philips Wake-Up Light review.
While it’s not to be used in lieu of an alarm clock, this handy app will aggravate the hell out of you until you’re awake. You have to vigorously shake your phone for the duration of time previously set, or it’ll keep going. Pair this with sixty seconds after your new alarm clock going off, and you’ll throw yourself into a frenzy that you’ll need to power through to get out of. By that point, you’re already up.
This Alarm Clock has many features that make it an excellent addition to your nightstand, work station, kitchen counter or end table. The first thing that separates this Alarm Clock from the rest are the two, easily accessible USB ports located directly on the front of the clock. These ports are fast charging and are perfect for your phone or tablet. Second, the illuminated digits are bright and easy to read in the dark. If you find them too bright when you are trying to fall asleep there is a...
Some clocks have several displays driven by a single mechanism, and some others have several completely separate mechanisms in a single case. Clocks in public places often have several faces visible from different directions, so that the clock can be read from anywhere in the vicinity; all the faces show the same time. Other clocks show the current time in several time-zones. Watches that are intended to be carried by travellers often have two displays, one for the local time and the other for the time at home, which is useful for making pre-arranged phone calls. Some equation clocks have two displays, one showing mean time and the other solar time, as would be shown by a sundial. Some clocks have both analog and digital displays. Clocks with Braille displays usually also have conventional digits so they can be read by sighted people.
Strong, durable, super large time display makes the model perfect for those who either want a big number clock, or for visually impaired individuals who need extra-large numerals, The red LED display on a black background, makes the contrast ideal for easy viewing. The electric power with battery backup lets you sleep with peace of mind and the extra-large snooze bar keeps nap-time within reach. This clock is a solid purchase.
This large farmhouse wall clock measures 36 inches This large farmhouse wall clock measures 36 inches across the face and features horizontal cedar wood slats a white distressed finish and hand painted black Roman numerals. Finish will vary slightly depending on each unique wood tone and grain pattern. The clock includes a high torque quartz movement antique-style spade ...  More + Product Details Close
In mechanical clocks, the power source is typically either a weight suspended from a cord or chain wrapped around a pulley, sprocket or drum; or a spiral spring called a mainspring. Mechanical clocks must be wound periodically, usually by turning a knob or key or by pulling on the free end of the chain, to store energy in the weight or spring to keep the clock running.
Many devices can be used to mark passage of time without respect to reference time (time of day, minutes, etc.) and can be useful for measuring duration or intervals. Examples of such duration timers are candle clocks, incense clocks and the hourglass. Both the candle clock and the incense clock work on the same principle wherein the consumption of resources is more or less constant allowing reasonably precise and repeatable estimates of time passages. In the hourglass, fine sand pouring through a tiny hole at a constant rate indicates an arbitrary, predetermined, passage of time. The resource is not consumed but re-used.

Fortunately, Ruggie takes the ease and convenience out of simply rolling over and slapping “snooze.” With Ruggie, you must apply pressure to a plush mat for three seconds to stop the alarm. The alarm can be set to 120 decibels, too, to further annoy you out of bed. For sake of perspective, 120 decibels is on par with the noise level of a chainsaw. Pleasant.

"Stripe Clock" is a modern metallic design created by the artist, Belle. Measured at 24 inches on each side, this metal art is made from a single sheet of metal expertly grinded and tinted and made in to a functional clock. It is mainly characterized by the bright stripe in the middle of the sheet of metal. Each stroke and grind pattern on this piece accentuates the beauty of the plain sheet of metal. The glimmer coming from the shallow grinds are like street lights illuminating the city in the...
At home in the most up-to-date atmospheres, this wall clock combines a Merlot Cherry finish with brushed nickel accents. The brushed nickel-finished pendulum and bezel add to the contemporary styling. The crisp white dial features black bar hour markers and black hour and minute hands. Finished in Merlot Cherry, a very dark maroon finish that is leaning toward black on an injected molded body. Quartz, battery operated movement.
Remember when the idea of chasing your alarm clock around the house was absolutely mad? Well, Clocky made it a reality, and they haven’t gone out of style yet. Bed shakers may work for some, but if you can ignore it and snooze on through, chasing your alarm clock around the room may be the next best thing. This mad machine can leap from three feet high, and if you’re trying to get some shut-eye on a Saturday, you can disable the wheels and make it stationary for the time being. Just don’t let that ruin your important meeting come 9:00 AM Monday morning. This little buzzer droid is going to make R2-D2 sounds while it zips around the room, egging you on to catch it.
From the 14th century, some clock towers in Western Europe were also capable of chiming at a fixed time every day; the earliest of these was described by the Florentine writer Dante Alighieri in 1319.[8] The most famous original striking clock tower still standing is possibly the one in St Mark's Clocktower in St Mark's Square, Venice. The St Mark's Clock was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from Reggio Emilia, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell (h. 1,56 m., diameter m. 1,27), which was put on the top of the tower where it was alternatively beaten by the Due Mori (Two Moors), two bronze statues (h. 2,60) handling a hammer.

A well-made large wall clock that looks good and runs smoothly can bring charm and functionality to any space. For a fresh take on the traditional clock, consider this eye-catching design... Introducing Rimwood by Umbra Every Umbra wall clock is tested in our factory before shipping to ensure it works perfectly. This, coupled with a sleek and modern design, ensures you’re getting a clock that not only tells time accurately but also looks great. This classically-inspired clock has a truly...
Some clocks, called 'flip clocks', have digital displays that work mechanically. The digits are painted on sheets of material which are mounted like the pages of a book. Once a minute, a page is turned over to reveal the next digit. These displays are usually easier to read in brightly lit conditions than LCDs or LEDs. Also, they do not go back to 12:00 after a power interruption. Flip clocks generally do not have electronic mechanisms. Usually, they are driven by AC-synchronous motors.

While an analog dial makes it easy, this clock is certainly not just for telling time! Let its colorful frame imbue a sense of playful appeal into your lodge-inspired living room look, lovely sitting atop your mantel as the fire flickers down below. Whether you're lounging on the sofa after a spirited skiing session or simply warming up with a steaming mug of hot cocoa, you can't go wrong by making the whole room shine with an antler-adorned chandelier hanging overhead and tying it all together...
The Mood Light Dual Radio with Nature Sounds Tabletop Clock will literally brighten your day with its color changing led and an easy-to-read 0.7” blue led display, and easy access top mounted touch controls. This model has a lot of unique features that set it apart from other clock radios, such as soothing nature sounds (brook/bubbles/forest), a multi-color led mood lamp and built-in 1 AMP charging port for charging your phone while you sleep. You can listen to your favorite FM or connect...
Here is a clock that will look great in any room in the house and it never needs a plug! This Water Clock is powered by ordinary tap water. Never needs batteries or electricity. Just fill this Water clock with water and you are on your way to more eco-friendly home. After about 6 months to a year you may need to dump the water out (your can pour it into a plant) and refill. The clock will remember the time as you do so. It even has an alarm. Great for traveling as well. Why would you ever use...
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