The other four vertices of the cube are North-East (ne), South-East (se), North-West (nw), and South-West (se).
The center of gravity is the ninth vertex: the compass needle. And the ninth vertex is the Blessed Trinity.
Note that the center of gravity is also the thirteenth edge in the case of the cubic clock. This means that the center of gravity is itself a cube inside the cube, and the inner cube has all the characteristics of the cube. Man is the reflection of the Blessed Trinity because man is the image of God.
In solar system level, the eight vertices are the eight planets, and the sun is the center of gravity where the eight planets meet. We know that the sun is made up of six square facets; when the six facets added to the nine vertices, the answer is 13 (the cubic clock).
In other words, the Holy of Holies is a cube reflecting a clock.