Yet, because the effect is caused by rotation, its occurrence is a necessary postulate not only from the standpoint of the aether theories, but equally well also from the anti-aether standpoint.
c) Thus this effect doesn't prove the aether.
6. The correctness of assertion a) follows without further ado, by thinking of the system as having a rectilinear uniform translation instead of the rotation process.[1] Then the effect is missing.
I omit the prove (which is in general easily given) because a remark by Sagnac himself in an older work[2] seems to speak for the fact, that his view doesn't contradict that of mine in this point.
7. Also with respect to assertion b), a schematizing sketch shall suffice:
First it is easily given: The occurrence of the effect is also then a necessary postulate, when one considers the process during the rotation, not in the way of § 4 (rotating disc thought as at rest, relative aether wind all around), but from