## Flattened Circles

Thom found these were of two main designs, Types A and B, which reduced the perimeter of a circle defined by an initial radius/diameter. Because they are fixed in their geometry, the ratio of perimeter reduction achieved and the equivalent "pi" between the circle and its flattened counterpart, can be stated as perimeter reduction PR:

- Type A: PR = 0.9114 ("pi" is then 3.0591)
- Type B: PR = 0.8604 ("pi" is then 2.9572)
- Type D: PR= 0.9343 ("pi" is then 3.0840)

[*MSB*, p28-9