ABSOLUTE Equation

, in Astronomy, is the sum of the optic and excentric equations. The apparent inequality of a planet's motion, arising from its not being equally distant from the earth at all times, is called its optic equation; and this would subsist even if the planet's real motion were uniform. The excentric inequality is caused by the planet's motion being not uniform. To illustrate this, conceive the sun to move, or to appear to move, in the circumference of a circle, in whose centre the earth is placed. It is manifest, that if the sun move uniformly in this circle, then he must appear to move uniformly to a spectator at the earth; and in this case there will be no optic nor excentric equation. But suppose the earth to be placed out of the centre of the circle; and then, though the sun's motion should be really uniform, it would not appear to be so, being seen from the earth; and in this case there would be an optic equation, without an excentric one. Imagine farther, the sun's orbit to be, not circular, but elliptical, and the earth in its focus: it will be full as evident that the sun cannot appear to have an uniform motion in such ellipse; so that his motion will then be subject to two equations; that is, the optic equation, and the excentric equation. See Equation, and Optic Inequality.

Absolute Number, in Algebra, is that term or member of an equation that is completely known, and which is equal to all the other, or unknown terms, taken together; and is the same as what Vieta calls the homogeneum comparationis. So, of the equation , or , the absolute number, or known term, is 36.

Absolute Gravity, Motion, Space, Time, &c. See the respective substantives.

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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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ABBREVIATION
ABERRATION
ABRIDGING
ABSCISS
ABSIS
* ABSOLUTE Equation
ABSTRACT Mathematics
ABSURD
ABUNDANT Number
ACADEMICIAN
ACADEMICS