Here the nulls remain four in number. There are three reds between the first null and the null above it, three yellows between the first null and the null beyond it, while the oranges increase in a double way.
Fig. 79.
Suppose this process of enlarging the number of the squares to be indefinitely pursued and the total figure obtained to be reduced in size, we should obtain a square of which the interior was all orange, while the lines round it were red and yellow, and merely the points null colour, as in [fig. 80]. Thus all the points, lines, and the area would have a colour.
Fig. 80.
We can consider this scheme to originate thus:—Let a null point move in a yellow direction and trace out a yellow line and end in a null point. Then let the whole line thus traced move in a red direction. The null points at the ends of the line will produce red lines, and end in null points. The yellow line will trace out a yellow and red, or orange square.
Now, turning back to [fig. 78], we see that these two ways of naming, the one we started with and the one we arrived at, can be combined.
By its position in the group of four squares, in [fig. 77], the null square has a relation to the yellow and to the red directions. We can speak therefore of the red line of the null square without confusion, meaning thereby the line AB, [fig. 81], which runs up from the initial null point A in the figure as drawn. The yellow line of the null square is its lower horizontal line AC as it is situated in the figure.
