| 1. | Rich-red | Dark-pink | Indigo |
| 2. | Green-blue | French-grey | Pale-pink |
| 3. | Sea-green | Dark-slate | Dark-slate |
| 4. | Emerald | Pale-pink | Green |
Round upper face in same order:—
| 1. | Reddish | Green-blue | Pale-yellow |
| 2. | Bright-blue | Bright-blue | Sea-green |
| 3. | Leaden | Sea-green | Leaden |
| 4. | Deep-yellow | Dark-green | Emerald |
Points:—
On lower face, going from left to right:—
| 1. | Quaker-green | Turquoise | Blue-tint |
| 2. | Peacock-blue | Fawn | Earthen |
| 3. | Orange-vermilion | Terra-cotta | Terra-cotta |
| 4. | Purple | Earthen | Buff |
On upper face:—
| 1. | Light-blue | Peacock-blue | Purple |
| 2. | Dull-purple | Dull-purple | Orange-vermilion |
| 3. | Deep-blue | Deep-blue | Deep-blue |
| 4. | Red | Orange-vermilion | Red |
If any one of these cubes be taken at random, it is easy enough to find out to what part of the Tessaract it belongs. In all of them, except 2, there will be one face, which is a copy of a face on 1; this face is, in fact, identical with the face on 1 which it resembles. And the model shows what lies in the unknown direction from that face. This unknown direction is turned into our space, so that we can see and touch the result of moving a square in it. And we have sacrificed one of the three original directions in order to do this. It will be found that the line, which in 1 goes in the 4th direction, in the other models always runs in a negative direction.
Let us take Model 8, for instance. Searching it for a face we know, we come to a Light-yellow face away from us. We place this face parallel with the Light-yellow face on Cube 1, and we see that it has a Green line going up, and a Green-grey line going to the right from the Buff point. In these respects it is identical with the Light-yellow face on Cube 1. But instead of a Blue line coming towards us from the Buff point, there is a Light-green line. This Light-green line, then, is that which proceeds in the unknown direction from the Buff point. The line is turned towards us in this Model 8 in the negative Y direction; and looking at the model, we see exactly what is formed when in the motion of the whole cube in the unknown direction, the Light-yellow face is moved an inch in that direction. It traces out a Salmon cube (v. Table on [p. 127]), and it has Sea-blue and Deep-green sides below and above, and Deep-crimson and Dark-grey sides left and right, and Dun and Light-yellow sides near and far. If we want to verify the correctness of any of these details, we must turn to Models 1 and 2. What lies an inch from the Light-yellow square in the unknown direction? Model 2 tells us, a Dun square. Now, looking at 8, we see that towards us lies a Dun square. This is what lies an inch in the unknown direction from the Light-yellow square. It is here turned to face us, and we can see what lies between it and the Light-yellow square.