Fig. 30.
In the figure ACDE ([fig. 30]) there are—
| 15 inside | 15 |
| 4 at corners | 1 |
a total of 16.
Now in the square ABGF, there are 16—
| 9 inside | 9 |
| 12 on sides | 6 |
| 4 at corners | 1 |
| 16 |
Hence the square on AB would, by the shear turning, become the shear square ACDE.
And hence the inhabitant of this world would say that the line AB turned into the line AC. These two lines would be to him two lines of equal length, one turned a little way round from the other.
That is, putting shear in place of rotation, we get a different kind of figure, as the result of the shear rotation, from what we got with our ordinary rotation. And as a consequence we get a position for the end of a line of invariable length when it turns by the shear rotation, different from the position which it would assume on turning by our rotation.