['e]quation equation. See {Equate}.]

1. A making equal; equal division; equality; equilibrium.

Again the golden day resumed its right, And ruled in

just equation with the night. --Rowe.

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.

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.

{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 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.

n 1: a mathematical statement that two expressions are equal

2: the act of regarding as equal [syn: {equating}]

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