Fig. 22.
If he wanted the figure made by Z0 . X11⁄2 . Y11⁄2 it would be a little more difficult. He would have to take Moena, a section halfway between Moena and Murex, Murex and another square which he would have to regard as an imaginary section half-a-unit further Y than Murex ([Fig. 22]). He might now draw a ground plan of the sections; that is, he would draw Syce, and produce Cuspis and Dos half-a-unit beyond Nugæ and Cista. He would see that Cadus and Bolus would be cut half-way, so that in the half-way section he would have the point a ([Fig. 23]), and in Murex the point c. In the imaginary section he would have g; but this he might disregard, since the cube goes no further than Murex. From the points c and a there would be lines going Z, so that Iter and Semita would be cut half-way.
Groundplan of Sections shown in Fig. 22.
Fig. 23.
He could find out how far the two lines a b and c d ([Fig. 22]) are apart by referring d and b to Lama, and a and c to Crus.
In taking the third order of sections, a similar method may be followed.
Fig. 24.