Let us now suppose a glass plate placed in front of the Block in its first position. On this plate let the axes X and Z be drawn. They divide the surface into four parts, to which we give the following names ([Fig. 17]):—

Z X = that quarter defined by the positive Z and positive X axis.

Z X = that quarter defined by the positive Z and negative X axis (which is called “Z negative X”).

Z X = that quarter defined by the negative Z and negative X axis.

Z X = that quarter defined by the negative Z and positive X axis.

The Block appears in these different quarters or quadrants, as it is turned round the different axes. In Z X the Moenas appear, in Z X the Alvus faces, in Z X the Syces. In each quadrant are drawn nine squares, to receive the faces of the cubes when they enter. For instance, in Z X we have the Moenas of:—

Z
ComesTibicenVestis
OstrumBidensScena
UrnaMolesSaltus
X

And in Z X we have the Alvus of:—

Z
MarsSpiculaComes
AlaUncusOstrum
SectorFrenumUrna
-X

And in the Z X we have the Syces of:—