Please allow me to add. Iimagine an observer. With motion of pin-point of laser beam (that hits the slopes of prism), he moves. Both motions are the same.

My views on "Prism Experiment" was changed partially as follows. Allow me to write, please.

Value of secular aberration is unknown. Then, true position of stars on the celestial sphere is unknown also. Coming direction of star light that is visible to come from just above is uncertain. However, this situation is not fatal to this thought experiment. Because, about phenomenon of the difference of the number of waves that enter both faces of prism, coming direction of star light is unrelated obviously (when the prism is at standstill against diagonal star light ray, the number of waves that reach optional two points on the both faces of prism is equal). Then, this experiment may disclose the direction of the motion against aether. But how about the speed ? I want entrust it to capable men (if it's able to measure the wave length of star light directly, the speed of motion against aether may be disclosed by other way).

This thought experiment seems to have connection with the Sagnac effect. There is a windmill. At the center of rotation, a light source is fixed (and light waves are emitted as concentric circle). At the tip of one blade, two mirrors are set. Angle of two mirrors to the light source is different (like letter X). When the blade does not rotate (guaranteed by "Newton's bucket"), two reflected lights may be the same : interference fringe may not show any change (interference of two reflected lights is supposed). But when the blade rotate (light source also), how about the interference fringe (it seems to continue changing : passing)? If changing is actual, the reason may be the same to the reason on prism and laser beam that is noted above.

In a forum, someone write, "the number of waves that enter both faces of the prism is equal". When light waves of a star come from just above, pointed out may be right. But when light waves come from a diagonal direction, the number of waves that enter both faces of the prism may not be equal.

i add, this experiment must be done in the vacuum of the outer space (such as moon's surface). It's because of the effect "extinction" of the air (about the rest, please see my web-site).

i am very sorry. This "proposal with prism" seems to be invalid. Reason is as follows. The number of light waves that reach optional two points of the face of the prism (per unit time) may be the same always. It's unrelated whether prism moves or is at a stand-still (relative to the light rays). i made mistake on such a simple logic. Alas !

As compensation for it, i show my question on M-M experiment below (it's written in other thread of this forum).
In a book "Teoria della relativita" By W.Pauli 1970, it's written as follows. "From view point of an observer who moves with moving medium, light must be considered that it's propagated (always and to every direction) at the speed of c/n in this medium" (translated from Japanese edition). In the air, it may be the same. Why it's not an explanation for M-M experiment ? For what reason ?

In a book "Special Relativity" By French, A.P. 1971, it's written that the air 0.1mm thick is enough to extinguish the memory of light source's motion. The notion of extinction seems to be about light speed (in the medium). In a forum (in English), i was shown a web-site below. See a heading "Optical Extinction".
http://www.edu-observatory.org/physics-faq/Relativity/SR/experiments.html

In a book, it's as follows. Direction of propagation of electromagnetic wave and flow of energy is the same. Energy is a vector quantity. If so, when the prism (in the outer space) is pointed at the direction from where plane waves of a star light are coming, value of energy that enter both faces of the prism will be different generally. And when the prism is turned on the direction of light path, it will be renewal of the M-M experiment.