Visible Speech
the system of expressing speech sounds by written symbols, invented by Prof. Alexander Melville Bell during the years 1849-1864. Its fundamental principle is, says its author, "that all relations of sound are symbolized by relations of form, each organ and each mode of organic action having its appropriate symbol, and all sounds of the same nature produced at different parts of the mouth (such as t and d, b and p) being represented by a single symbol turned in a direction corresponding to the organic position." The shapes of these symbols not being founded on any existing alphabet, the system here can only be illustrated illustrated, in the absence of the peculiar fount, by two that bear an accidental likeness to our current letters-O, symbolizing that the throat is open, and C, that part of the mouth is contracted.
Among the advantages claimed for visible speech by Professor Bell are its power of representing the exact sounds of foreign languages (even Zulu clicks), and the facilities offered by it toward teaching the illiterate and blind to read, and the deaf and dumb to speak. But though the first at least of these claims has been established by rigid tests, and is admitted by A. J. Ellis and other eminent phonologists, the system has not, as its inventor hoped, been taken up by the government. See Bell's "Visible Speech," "The Science of Universal Alphabetics" (London, 1867). VISION by them. The apparent color of an object depends partly on the wave length or wave lengths of the incident light waves, single or mixed, and partly on the state of the eye itself itself, as in color blindness, or after taking santonine, which makes external objects look yell yellow, or in jaundice. The apparent brightness of an object depends on the amplitude of the light waves which pass from it to the eye; and the smallest perceptible difference of brightness always bears a nearly constant ratio to the full intensity of the bright objects (Fechner's psychophysical law). As between different colors the eye perceives them with different intensities, even when the physical intensity is the same; thus yellow appears brighter in a bright light than an equally intense red; and as light fades away the different colors fade away unequally, so that the ratio in Fechner's law is different for each color; red and yellow disappear first, blue last; and thus in a dim light the blue is the brightest.
The leading problems in the theory of vision are, however, those which deal with the nature of our perception of distance and of three-dimensional extension. According to Bishop Berkeley, whose views ("On the Theory of Vision") have met with th the widest acceptance, we do not by means of sight pe perceive either that external objects are outside ourselves or their distance from us; but this knowledge is derived from touch and from our experience of motion from place to place; and as our experience is in general uniform, we come to associate the visible with the tangible so readily that we fancy we directly see visible objects. As regards the distance of any given point, Berkeley maintains that this cannot be seen, "for distance being a line directed endwise to the eye, it projects only one point in the fund of the eye; which point remains invariably the same, whether the distance be longer or shorter." This may be true, and yet the eye may be obliged to put forth perceptibly different efforts in order to discriminate 680-687 points situated at different distances. 687-701 Rays proceeding from the distant point