An elegant attempt to determine the speed of the Earth through the ether. By splitting a single beam of light and passing it along two beam lines at 90 degrees from one another, then rotating the entire apparatus through 360 degrees, it should have been possible to detect when light in one beam line was travelling parallel to the motion of the Earth through the ether, and when it was not. Unfortunately, very careful work on the experiment demonstrated that the speed of light was constant irrespective of what direction it was moving in, and so it could not be considered as wave motion in the medium of the ether.

Most amusingly, Webster 1913 treats ether as the real medium through which light moves.