[f. Gr. χρόνο-ς time + μέτρον measure.]
1. An instrument for measuring time; spec. applied to time-keepers adjusted to keep accurate time in all variations of temperature. They differ from watches in having a more perfect escapement and a compensation balance, and are used for determining longitude at sea, and for other exact observation. To rate a chronometer: to compare its daily loss or gain with the true time.
Some watches are named half-chronometers.
[1715. Kersey, Chronometrum or Chronoscopium Perpendiculum, a Pendulum to measure Time with.]
1713. Derham, Phys.-Theol., I. iv. (ed. 3), 28, note (J.). According to my own Observations made with … a very accurate Pendulum Chronometer.
1780. J. Arnold (title), Account of … a Pocket Chronometer.
1787. Bonnycastle, Astron., x. 159. Method for finding the longitude of places … by means of a chronometer.
1812. Woodhouse, Astron., viii. 49. The time of the transit is to be marked by a clock or chronometer.
1855. Emerson, Misc. Fort. Repub., Wks. (Bohn), III. 387. The sailors sail by chronometers that do not lose two or three seconds in a year.
b. transf. and fig. ‘Time-measurer.’
1836. Cdl. Wiseman, Sc. Relig., I. vi. 360. Deluc was the first … to observe and collect such data, to which he gave the name of Chronometers.
1872. Yeats, Techn. Hist. Comm., 190. Sun and stars, whose rising and setting formed the grand chronometer of Nature.
† 2. Mus. An instrument for indicating the time or movement of a composition; a METRONOME.
1837. Penny Cycl., VII. 135/2. The musical chronometer is by no means a modern contrivance.
3. attrib. and Comb., as chronometer-balance, -box, -maker; chronometer-escapement, an escapement in which the free movement of the balance is opposed by the wheels at only one point in a complete oscillation.
1878. Markham, Gt. Frozen Sea, v. 63. A *chronometer-box was picked up, but empty.
1874. Knight, Dict. Mech., The *chronometer escapement … is the most perfect, delicate, and satisfactory in its operation, of all the escapements.
1837. Penny Cycl., VII. 135/2. The most eminent *chronometer-makers in this country.
