ORDER
, in Architecture, a system of the several members, ornaments, and proportions of a column and pilaster.
There are five Orders of columns, of which three are Greek, viz, the Doric, Ionic, and Corinthian; and two Italic, viz, the Tuscan and Composite. The three Greek Orders represent the three different man- ners of building, viz, the solid, the delicate, and the middling: the two Italic ones are imperfect productions of these.
Order, in Astronomy. A planet is said to go according to the order of the signs, when it is direct; proceeding from Aries to Taurus, thence to Gemini, &c. As, on the contrary, it goes contrary to the Order of the signs, when it is retrograde, or goes backward, from Pisees to Aquarius, &c.
Order, in the Geometry of Curve Lines, is denominated from the rank or Order of the equation by which the geometrical line is expressed; so the simple equation, or 1st power, denotes the 1st Order of lines, which is the right line; the quadratic equation, or 2d power, defines the 2d Order of lines, which are the conic sections and circle; the cubic equation, or 3d power, defines the 3d Order of lines; and so on.
Or, the Orders of lines are denominated from the number of points in which they may be cut by a right line. Thus, the right line is of the 1st Order, because it can be cut only in one point by a right line; the circle and conic sections are of the 2d Order, because they can be cut in two points by a right line; while those of the 3d Order, are such as can be cut in 3 points by a right line; and so on.
It is to be observed, that the Order of curves is always one degree lower than the corresponding line; because the 1st Order, or right line, is no curve; and the circle and conic sections, which are the 2d Order of lines, are only the 1st Order of curves; &c.
See Newton's Enumeratio Linearum Tertii Ordinis.
