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.

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