วันจันทร์ที่ 3 พฤษภาคม พ.ศ. 2553
A Brief History of the Alarm Clock
On occasion we all feel like throwing our alarm clocks across the room. It is designed to make an annoying sound at a certain time to make sure we wake up. Sometimes alarm clocks are used for other reminders as well. To stop the sound of an alarm clock, a button or handle has to be pressed while others stop automatically after a few minutes. A traditional analog alarm clock comes with an extra hand that specifies the time in which the alarm will be activated.
Conventional mechanical alarm clocks have one or two bells that ring but digital clocks can produce other noises. Simple battery-powered clocks usually make a loud buzzing sound or another similar sound to wake a sleeper. On the other hand, novelty clocks can speak, laugh, or sing. Some clocks have radios that play at certain times and are known as clock radios.
The ancient Greek philosopher Plato (428348 B.C.) supposedly had a big water clock with an unspecified alarm signal like the sound of a water organ. He used this at night, apparently for marking the start of his lectures at dawn. The late Roman Senator Cassiodorus described in his rule book for monastic life a water clock as a useful alarm for the soldiers of Christ. Prior to 529 B.C., the Christian rhetorician Procopius also talked in detail about a complex public striking clock in his hometown in Gaza that featured an hourly gong and figures moving mechanically day and night.
The first mechanical clocks were made in the 14th century, and were big monumental clocks. By 1620, household clocks were used and some of them had alarm mechanisms. The alarm is simple in concept, often with a cam that rotates every 12 hours. It has a notch into which a lever can fall, releasing a number of gears that drive a hammer that repeatedly strikes a bell until it runs down or is shut off.
Moshi Lifestyle offers the latest in voice controlled technology with voice activated alarm clocks.
Article Source: http://EzineArticles.com/?expert=Andy_A_Johnston
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