Allow me to rewrite again, please. Rewritten is the latter half.
It's a variation of the Fizeau experiment (on the light speed in moving medium : 1851). A pillar made of glass is set horizontally. Two lights (emitted from two light sources) are passing through this glass (supposed to be from left to right). One light source is at a stand-still (distance between the glass is fixed). Another light source is approaching toward the glass at an uniform speed. The frequency of two incident lights is just the same (thus arranged). Under this situation, the frequency of two lights that go out the glass is the same obviously (if not so, the number of waves that exist in the glass may increase or decrease endlessly). From above, what is able to say ? If the speed of two incident lights is the same, light speed in the glass (also in the water and so on) may be the same (because wave number is the same). Therefore, if speed of two lights in the glass is not the same (in above thought experiment), the emission theory seems to be right. To dear administrator, : The other day, i made mistakes. i ask, please erase mistakes and this.