Nowadays, we know with greater accuracy that there are three components which can displace one another under the influence of surroundings of another colour. Of course, our perception must actually carry this out, and since it is therefore reasonable to assume that our eyes and brain will try to perceive the differences occurring in nature as clearly as possible, this explanation conforms with the displacement represented by the colour-circle. The laws of colour contrast occupied Chevreul during his search for an adequate organisation of colours, as required for the manufacture of textiles. For this purpose, he designed the 72 segment colour circle shown here. It is worth noting that in his colour-circle, Chevreul arranges each of the saturated colours on a varying radius within its associated segment.
Pure yellow lies nearer to the centre than pure blue.
Pure red lies at point 15 on the scale. By this means, the values of colour hue for the different pigments are given a position more appropriate than in preceding systems. The segments arising in this way are thus divided into six zones, and each radius is divided into 20 sections in the form of a ladder, in order to specify the different brightness levels. With his hemisphere, Chevreul attempted to provide us with a spacial representation of the colours appearing in his two dimensional colour-circle. The black axis of the hemisphere thus becomes a pointer, pivoting to select the different levels on a scale.