# EQUALITY

, the exact agreement of two things in respect of quantity. Those figures are equal which may occupy the same space, or may be conceived to possess the same space, by the flexion or transposition of their parts. See a learned discourse upon this, by Dr. Barrow, in the 11th and 12th of his Mathematical Lectures.

Equality, in Algebra, the relation or comparison between two quantities that are really or effectually equal. See Equation.

Equality, in Algebra, is usually denoted by two equal parallel lines, as = : thus , i. e. 2 plus 3, are equal to 5. This character =, was first introduced by Robert Recorde. Des Cartes, and some others after him, use the mark instead of it: as 2 + 3 5.

Equality, in Astronomy. *Circle of* Equality,
or the Equant. See Circle and Equant.

*Ratio* or *Proportion* of Equality, is that between
two equal numbers or quantities.

*Proportion* of Equality *evenly ranged,* or *ex æquo
ordinata,* is that in which two terms, in a rank or series,
are proportional to as many terms in another series,
compared to each other in the same order, i. e.
the first of one rank to the first of another, the 2d to
the 2d, &c.

*Proportion of* Equality *evenly disturbed,* called also
*ex æquo perturbata,* is that in which more than two terms
of one rank, are proportional to as many terms of another,
compared to each other in a different and interrupted
order; viz, the 1st of one rank to the 2d of
another, the 2d to the 3d, &c.