Equation of time
Equation E*qua"tion, n. [L. aequatio an equalizing: cf. F. ['e]quation equation. See {Equate}.] 1. A making equal; equal division; equality; equilibrium. [1913 Webster]

Again the golden day resumed its right, And ruled in just equation with the night. --Rowe. [1913 Webster]

2. (Math.) An expression of the condition of equality between two algebraic quantities or sets of quantities, the sign = being placed between them; as, a binomial equation; a quadratic equation; an algebraic equation; a transcendental equation; an exponential equation; a logarithmic equation; a differential equation, etc. [1913 Webster]

3. (Astron.) A quantity to be applied in computing the mean place or other element of a celestial body; that is, any one of the several quantities to be added to, or taken from, its position as calculated on the hypothesis of a mean uniform motion, in order to find its true position as resulting from its actual and unequal motion. [1913 Webster]

{Absolute equation}. See under {Absolute}.

{Equation box}, or {Equational box}, a system of differential gearing used in spinning machines for regulating the twist of the yarn. It resembles gearing used in equation clocks for showing apparent time.

{Equation of the center} (Astron.), the difference between the place of a planet as supposed to move uniformly in a circle, and its place as moving in an ellipse.

{Equations of condition} (Math.), equations formed for deducing the true values of certain quantities from others on which they depend, when different sets of the latter, as given by observation, would yield different values of the quantities sought, and the number of equations that may be found is greater than the number of unknown quantities.

{Equation of a curve} (Math.), an equation which expresses the relation between the co["o]rdinates of every point in the curve.

{Equation of equinoxes} (Astron.), the difference between the mean and apparent places of the equinox.

{Equation of payments} (Arith.), the process of finding the mean time of payment of several sums due at different times.

{Equation of time} (Astron.), the difference between mean and apparent time, or between the time of day indicated by the sun, and that by a perfect clock going uniformly all the year round.

{Equation clock} or {Equation watch}, a timepiece made to exhibit the differences between mean solar and apparent solar time. --Knight.

{Normal equation}. See under {Normal}.

{Personal equation} (Astron.), the difference between an observed result and the true qualities or peculiarities in the observer; particularly the difference, in an average of a large number of observation, between the instant when an observer notes a phenomenon, as the transit of a star, and the assumed instant of its actual occurrence; or, relatively, the difference between these instants as noted by two observers. It is usually only a fraction of a second; -- sometimes applied loosely to differences of judgment or method occasioned by temperamental qualities of individuals.

{Theory of equations} (Math.), the branch of algebra that treats of the properties of a single algebraic equation of any degree containing one unknown quantity. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Equation of time — Time Time, n.; pl. {Times}. [OE. time, AS. t[=i]ma, akin to t[=i]d time, and to Icel. t[=i]mi, Dan. time an hour, Sw. timme. [root]58. See {Tide}, n.] 1. Duration, considered independently of any system of measurement or any employment of terms… …   The Collaborative International Dictionary of English

  • equation of time — n. Astron. the constantly changing difference between the true sundial (apparent solar time) and mean solar time: the apparent solar time may be as much as 16 minutes ahead or behind: see ANALEMMA …   English World dictionary

  • Equation of time — The equation of time is the difference over the course of a year between time as read from a sundial and time as read from a clock, measured in an ideal situation (ie. in a location at the centre of a time zone, and which does not use daylight… …   Wikipedia

  • equation of time — The amount of time by which the mean sun leads or lags behind the true sun at any instant. Its value is positive or negative, depending on whether the true sun is ahead of or behind the mean sun. Its value never exceeds 16 1 /2 min. It is the… …   Aviation dictionary

  • equation of time — equa′tion of time′ n. astron. apparent time minus mean solar time, ranging from minus 14 minutes in February to over 16 minutes in November …   From formal English to slang

  • equation of time — the difference between mean solar time (as shown by clocks) and apparent time (indicated by sundials), which varies with the time of year. → equate to/with …   English new terms dictionary

  • equation of time — Date: 1667 the difference between apparent time and mean time usually expressed as a correction which is to be added to apparent time to give local mean time …   New Collegiate Dictionary

  • equation of time — the difference between mean solar time and apparent time usually expressed as a correction which is to be added to apparent time to give local mean solar time and which never exceeds +16 minutes …   Useful english dictionary

  • equation of time — Astron. apparent time minus mean solar time, ranging from minus 14 minutes in February to over 16 minutes in November. [1720 30] * * * …   Universalium

  • Equation of a curve — Equation E*qua tion, n. [L. aequatio an equalizing: cf. F. [ e]quation equation. See {Equate}.] 1. A making equal; equal division; equality; equilibrium. [1913 Webster] Again the golden day resumed its right, And ruled in just equation with the… …   The Collaborative International Dictionary of English

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