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Definition: Pocket Watch |
Pocket WatchNoun1. A watch that is carried in a small watch pocket. Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
(From Wikipedia, the free Encyclopedia)
A clock (from the Latin cloca, "bell") is an instrument for measuring time.
The display can be analog, with hands, or digital, expressing the time in digits. The former has a circular scale of 12 hours, which also serves as a scale of 60 minutes, and often also as a scale of 60 seconds; the latter has an hour range of 1-12, with an indication am/pm, or 0-23.
They are in homes and offices; smaller ones (watches) are carried along (alternatively, people can read the time from their mobile phone); big ones are in public places, e.g. a train station or church.
A small clock is also often permanently shown in a corner of computer displays.
The main purpose of a clock is not always to display the time. It may also be used to control a device according to time, e.g. a VCR and a time bomb. For an alarm clock both are important.
A clock, by measuring time (e.g. in seconds). supplies a numerical comparison between the durations of different time intervals. For example, a clock will provide the ratio of the duration of one day to the duration of a different day (for example, the earth is spinning slower today than it did a billion years ago. If the earth's spin is used as a clock, each rotation will take exactly one day, by definition.)
A clock can be a physical instrument (an especially accurate one is called a chronometer) or refer to an abstract system of time measurement (see calendar).
Modern clocks define constant units of time: an hour is always sixty minutes, of sixty seconds each.
The medieval canonical hours, however, were the intervals between set times of prayer: they differed in length, and varied as the times of sunrise and sunset shifted.
Navigation
Accurate navigation by ships beyond the sight of land depends on the ability to measure latitude and longitude. Latitude is fairly easy to determine through celestial navigation, but the measurement of longitude requires accurate measurement of time. This need was a major motivation for the development of accurate mechanical clocks.
The notion of an ideal clock
An ideal clock appropriately measures the ratio of the duration of natural processes, and thus will give the appropriate time measure for use in physical theories. Therefore, to define an ideal clock in terms of any physical theory would be circular. An ideal clock is more appropriately defined in relationship to the set of all physical processes. This leads to the following definitions:
This definition can be further improved by the consideration of successive levels of smaller and smaller error tolerances.
- A clock is a recurrent process and a counter
- A good clock is one which, when used to measure other recurrent processes, finds many of them to be periodic.
- An ideal clock is a clock (i.e., recurrent process) that makes the most other recurrent processes periodic.
While not all physical processes can be surveyed, the definition should be based on the set of physical processes which includes all individual physical processes which are proposed for consideration. Since atoms are so numerous and since, within current measurement tolerances, they all beat in a manner such that if one is chosen as periodic then the others are all deemed to be periodic also, it follows that atomic clocks represent ideal clocks to within present measurement tolerances and in relation to all presently known physical processes. However, they are not so designated by fiat. Rather, they are designated as the current ideal clock because they are currently the best instantiation of the definition.
Notable clocks
- Tower Clock (see Big Ben, its largest bell) at the Palace of Westminster, London
- Peace Tower clock at the Centre Block of the Parliament of Canada, Ottawa
- 10,000-year Clock of the Long Now
- Doomsday clock shows the symbolic minutes to midnight where midnight represents destruction by nuclear war
Types of clock
- pendulum clock
- hourglass
- water clock
- quartz clock
- radio clock
- cuckoo clock
- chronometer
- watch
- analog clock with digital display
- sundial
- stopwatch
- game clock
- countdown clock
See also
- time standard
- Allan variance
- horology
- metrology
- timeline of time measurement technology
- Clock signal (digital circuits)
- biological clocks
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Clock."
| Context | Synonyms within Context (source: adapted from Roget's Thesaurus). |
Instantaneity | Clock, wall clock, pendulum clock, grandfather's clock, cuckoo clock, alarm clock, clock radio; watch, pocket watch, stopwatch, Swiss watch; atomic clock, digital clock, analog clock, quartz watch, water clock; chronometer, chronoscope, chronograph; repeater; timekeeper, timepiece; dial, sundial, gnomon, horologe, pendulum, hourglass, clepsydra; ghurry. |
| Source: adapted from Roget's Thesaurus. | |
Crosswords: Pocket Watch |
| English words defined with "pocket watch": fob ♦ watch chain, watch guard, watch pocket. (references) |
| The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com. |
| Language | Translations for "pocket watch"; alternative meanings/domain in parentheses. | |
Arabic | ساعة الجيب. (various references) | |
Finnish | taskukello. (various references) | |
German | Taschenuhr. (various references) | |
Japanese Kanji | 懐中時計 . (various references) | |
Japanese Katakana | かいちゅうどけい, かいちゅうとけい. (various references) | |
Pig Latin | ocketpay atchway.(various references) | |
Portuguese | relógio de bolso (watch-pocket). (various references) | |
Serbo-Croatian | džepni sat. (various references) | |
| Source: compiled by the editor from various translation references. | ||
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "a-c-c-e-h-k-o-p-t-t-w" | |
-3 letters: cachepot. | |
-4 letters: cathect, hotcake, peacock, petcock, toccate, towpath. | |
-5 letters: accept, cachet, capote, cheapo, copeck, cottae, cowpat, cowpea, hepcat, packet, pocket, tacket, teapot, thwack, toecap, whacko. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
| 1. Definition 2. Crosswords 3. Images: Slideshow 4. Expressions: Internet | 5. Translations: Modern 6. Anagrams 7. Bibliography |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
