chart. From the eye there branches a sort of geneo- logical tree. The fork to the left runs down into two colours, black and white, symbolizing the action of the rods in the eye. The rods being that part of the eye which recognizes the black and white in one's surroundings. Then the right-hand fork is sub-divided. One sub division gives yellow and blue. The other gives red and seagreen. This right-hand fork symbolizes the action of the cones in the eye and the cones themselves fall into two categories. The one, the older of the two, picks up the yellow and blue; the other, the younger, i.e., the latest in the process of evolution, picks up the red and seagreen. Because the red-seagreen group is the latest evolved, it is naturally the weakest; the first to fall to disease or some other physical defectand so colour blindness is found more prevalent in the red-seagreen group. Here, then, is the basic principle of colour recognition based upon vision. Now you will see that I have drawn a double-cone, the apex of which rests in the eye and the base of which rests upon the symbol of The Coal Industry* in the bottom left-hand corner of my design. This double cone represents The Ostwald Colour Solid. The double cone of The Ostwald Theory is the one which develops as you revolve an equilateral triangle upon one of its sides, using that side as the axis. There is a specific reason why Ostwald insists upon this particular type of cone. His Colour Equation gives c w b 1 where c colour, w white, and b black; the whole, when translated into terms of per centages, resulting in unity. So with an equilateral triangle of this nature it is a geometric truism "that the sum of the three lines drawn from any point inside this triangle parallel to the sides and taken to represent the respective amounts of c, w and b in the colour at that point, must always be equal to unity, i.e., to the length of a side" (J. Scott Taylor, A Short Account of The Ostwald Colour System This, then, is the beginning of the plan of the Colour World. If you look at the Solid when it has been "made up" and the created solid is a thing of startling beauty, with its subtle gradations and its simplicityyou see the whole idea laid before you as plainly as one sees a cathedral arise from the plan and elevation of the archi tect's drawings. In fact, the Colour Solid is the archi tect's elevation drawing of the city of colour and Ostwald is that architect. At the apex of the solid is pure white which bears the Indicating the link between the original Ostwald colours and The Coal Tar Dye Industry. 220 index symbol (a). At the base of the solid is a black which bears the index symbol (p), and between points (a) and (p) stretches the grey vertical axis showing step by step the easy transition from white to black. This axis becomes the spine or spindle around which the solid turns. This vertical axis stands erect through a circle of pure hues, like a double-sided phallic symbol in the days of its vitality. So you have the image of a grey axis, encircled at the midway point by a ring of hues. This ring or circle of hues contains twenty-four hues, all equidistant the one from the other so that the eye travels easily and quickly from hue to hue. Diagram 1 Now as this circle of hues is divided into 24 parts and each part a colour, it follows logically that as the eye travels from each one of these hues towards the apex of the cone where stands the white pinnacle, the quantity of pure colour decreases as the quantity of pure white increases. This transition from the hue to the white is gradual and every step is determined arith metically in terms of the Colour Equation c w b= 1 Because the colours which now appear upon the upper cone show a white content, these newly formed colours are known as the tints. Going back again to the circle of hues, allow the eye to travel from this circle towards the base where the black is situated. Again it stands to reason that as one moves away from the hue and draws nearer and nearer to the black the quantity of hue decreases as the quantity of black increases. The eye travels with ease over these new colours which show a black content and these new colours are termed the shades. Going again to the circle of hues, there is yet another point of contact to be explored. This is the one which lies upon the grey axis itself and situated midway between (a) and (p). All colours working from the circle towards the central point decrease in hue content as they increase in a grey contentand these in terms of practical exposition we call the shaded tints. To come now to the practical side of this workthe side that interests the majority of folk in the colour world there is this to be said at once. It is possible to have ideal colours which are not possibleor which are practically impossible to obtain in paint. This may be instanced by reference to the black and the white. The ideal black, the ideal white and the ideal full colour would be those entirely free, the black entirely free from white, the white entirely free from black, and the full colour entirely free from black and white. This is not possible in terms of paint except perhaps in the instance of Gouache White of special manufacture. So the following table of contents shows

Industrial Arts en | 1936 | | page 60