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.