atomic clocks

atomic clocks
Clock Clock (kl[o^]k), n. [AS. clucge bell; akin to D. klok clock, bell, G. glocke, Dan. klokke, Sw. klocka, Icel. klukka bell, LL. clocca, cloca (whence F. cloche); al perh. of Celtic origin; cf. Ir. & Gael. clog bell, clock, W. cloch bell. Cf. {Cloak}.] 1. A machine for measuring time, indicating the hour and other divisions; in ordinary mechanical clocks for domestic or office use the time is indicated on a typically circular face or dial plate containing two hands, pointing to numbers engraved on the periphery of the face, thus showing the hours and minutes. The works of a mechanical clock are moved by a weight or a spring, and it is often so constructed as to tell the hour by the stroke of a hammer on a bell. In electrical or electronic clocks, the time may be indicated, as on a mechanical clock, by hands, but may also be indicated by direct digital readout, with the hours and minutes in normal Arabic numerals. The readout using hands is often called analog to distinguish it from the digital readout. Some clocks also indicate the seconds. Clocks are not adapted, like the watch, to be carried on the person. Specialized clocks, such as {atomic clocks}, may be constructed on different principles, and may have a very high precision for use in scientific observations. [1913 Webster +PJC]

2. A watch, esp. one that strikes. [Obs.] --Walton. [1913 Webster]

3. The striking of a clock. [Obs.] --Dryden. [1913 Webster]

4. A figure or figured work on the ankle or side of a stocking. --Swift. [1913 Webster]

Note: The phrases what o'clock? it is nine o'clock, etc., are contracted from what of the clock? it is nine of the clock, etc. [1913 Webster]

{Alarm clock}. See under {Alarm}.

{Astronomical clock}. (a) A clock of superior construction, with a compensating pendulum, etc., to measure time with great accuracy, for use in astronomical observatories; -- called a regulator when used by watchmakers as a standard for regulating timepieces. (b) A clock with mechanism for indicating certain astronomical phenomena, as the phases of the moon, position of the sun in the ecliptic, equation of time, etc.

{Electric clock}. (a) A clock moved or regulated by electricity or electro-magnetism. (b) A clock connected with an electro-magnetic recording apparatus.

{Ship's clock} (Naut.), a clock arranged to strike from one to eight strokes, at half hourly intervals, marking the divisions of the ship's watches.

{Sidereal clock}, an astronomical clock regulated to keep sidereal time. [1913 Webster]

The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Atomic clock — Nuclear clock redirects here. For the clock as a measure for risk of catastrophic destruction, see Doomsday Clock. For a clock updated by radio signals (commonly but inaccurately called an atomic clock ), see Radio clock. For the album by Zion I …   Wikipedia

  • atomic clock — an extremely accurate electronic clock regulated by the resonance frequency of atoms or molecules of certain substances, as cesium. [1935 40] * * * ▪ instrument       type of clock that uses certain resonance frequencies of atoms (usually cesium… …   Universalium

  • atomic time — ▪ physics       timescale generated by atomic clocks (atomic clock), which furnish time more accurately than was possible with previous astronomical means (measurements of the rotation of the Earth and its revolution about the Sun). International …   Universalium

  • atomic clock — noun a timepiece that derives its time scale from the vibration of atoms or molecules • Hypernyms: ↑timepiece, ↑timekeeper, ↑horologe • Hyponyms: ↑ammonia clock, ↑caesium clock * * * noun, pl ⋯ clocks [count] : a special kind of clock …   Useful english dictionary

  • International Atomic Time — ( [ TAI] , from the French name Temps Atomique International) is a high precision atomic time standard that tracks proper time on Earth s geoid. It is the principal realisation of Terrestrial Time,… …   Wikipedia

  • Primary Atomic Reference Clock in Space — The Primary Atomic Reference Clock in Space or PARCS is an atomic clock mission once scheduled to fly on the International Space Station (ISS) in 2008, but cancelled to make way for the Vision for Space Exploration.[1] The mission, to have been… …   Wikipedia

  • international atomic time — a system of measuring time based on atomic clocks that measure the second as defined as the SI unit of time. Abbr.: IAT * * * International Atomic Time noun An international standard of time synchronized by atomic clocks (abbrev TAI) • • • Main… …   Useful english dictionary

  • international atomic time — a system of measuring time based on atomic clocks that measure the second as defined as the SI unit of time. Abbr.: IAT * * * …   Universalium

  • International Atomic Time — noun an international time standard, based on the SI unit of the second, synchronised by means of atomic clocks and satellites, introduced in 1958. Abbrev.: TAI …   Australian English dictionary

  • List of clocks — This is a list of clocks that have attained a level of notability because of their historical importance, accuracy, exceptional artistry, or architectural value. North America *Colgate Clock New Jersey, United States *Clock of the Long Now, not… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”