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.
Some clocks, usually digital ones, include an optical projector that shines a magnified image of the time display onto a screen or onto a surface such as an indoor ceiling or wall. The digits are large enough to be easily read, without using glasses, by persons with moderately imperfect vision, so the clocks are convenient for use in their bedrooms. Usually, the timekeeping circuitry has a battery as a backup source for an uninterrupted power supply to keep the clock on time, while the projection light only works when the unit is connected to an A.C. supply. Completely battery-powered portable versions resembling flashlights are also available.

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.


You can choose from an analog styled clock to a digital one. Our alarm clocks can vary from old, retro, 1950 styled clocks to modern 2013. Depending on your desire, we have wind up alarm clocks, clocks that do or do not tick, or clocks with or without a built in radio. We have clocks for children, clocks that run on battery, or ones that plug directly into an outlet.
Stay on schedule and charge a range of devices with this innovative iHome dual-alarm clock. Place your compatible smartphone on top of the Qi-certified device for swift wireless charging, or plug your phone into the clock’s handy powered USB port. This iHome dual-alarm clock incorporates NFC technology, so you can connect an array of Bluetooth-enabled devices with a quick touch.
After a long day at work, school, or running errands, it's tough to beat the feeling of climbing into your bed for a good night's rest. When you're feeling tired, it's tough to get back out of bed in the morning to start all over again. With the right alarm clock, you can wake up to pleasant sounds that make it a little easier to get up and going. With a wide selection of alarm clock options available at JCPenney, you can find the style that fits with the look and feel of your bedroom while delivering the functionality you need.
These mechanical clocks were intended for two main purposes: for signalling and notification (e.g. the timing of services and public events), and for modeling the solar system. The former purpose is administrative, the latter arises naturally given the scholarly interests in astronomy, science, astrology, and how these subjects integrated with the religious philosophy of the time. The astrolabe was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce a working model of the solar system.
Water clocks, also known as clepsydrae (sg: clepsydra), along with the sundials, are possibly the oldest time-measuring instruments, with the only exceptions being the vertical gnomon and the day counting tally stick.[9] Given their great antiquity, where and when they first existed is not known and perhaps unknowable. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and in Egypt around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world.[10]

Pairing a simple design with a contrasting black-and-silver palette, this eye-catching 12" wall clock instantly elevates your favorite aesthetic. Its round silhouette blends effortlessly into both casual or formal spaces, while its clean profile adds sophistication to your decor. Lean into this wall clock's versatility by adding it to a transitional living room arrangement alongside a mid-century-inspired sofa and gently-tufted barrel chairs for a cohesive seating space. Anchor the ensemble...

“This alarm clock will wake you up! I’m totally deaf in one ear and partially deaf in the other. Alarm clocks I used before I purchased this one might as well have been turned off if I happened to have my good ear on the pillow when they went off. This one is loud! Now having said that, its loudness is adjustable, and I found that a low setting of two works just fine for me, but if I am particularly concerned about being awakened, I also set the vibrating disk, which is slipped under the mattress. Believe me: Even if you are totally deaf in both ears, this will wake you up. I was skeptical about the vibrator because I have a thick mattress, but it works with no problem at all! I wholeheartedly recommend this alarm clock for anyone who is hearing impaired.”
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