DIMENSION (Lat. dinicasio, from (tinware, to measure off. from di-. apirt metiri, to meas ure). In geometry, a line, whether straight or curved. has one dimension, viz. length: a plane surface has two, length and breadth; and a solid has three, length, breadth, and thickness. In algebra. the term dimension is applied in much the sense as degree, to express the number of literal factors contained in a product. Thus ay. tab are said to be of two dimen a=be sions: of three; and so on. In physical measurements the power to which the unit (q.v.) of measure enters, determines the dimension of the expression. The form of any material body may be described in terms of at least three dimension:, hence the space in which these forms or ti,mres exist is usually regarded as tridimensional. However, the possibility of the existence of a space having more than three dimensions has been discussed. The possibility
of such space is conceivable and such an hypoth esis is of service to the mathematician in ex plaining analytic phenomena. Since points, lines, and in general, generate by their mo tion lines, surfaces, and solids, respectively, it may he inferred that some movement of a figure of three dimensions can generate a figure of four dimensions. Analytically it is only necessary to imagine four parameters or coordMates belonging to each point of four-dimensional space, or five in five-dimensional space, and so on, in order to develop a system of analysis as logical in it self as that of only three dimensions. Figures to represent some features of four-dimensional bodies have been imagined. See CHASLES ; CHAR .terEinsTic: and GEOMETRY.