http://www.berkeleyscience.com/relativity.htm
"Michelson and Morley designed an experiment to detect the ether and measure its influence on the speed of light. (...) Let's do the math. Assume light travels at a constant velocity c in the ether. Suppose the apparatus is moving through the stationary ether with velocity v. In the direction of motion, the time for the light to reach the mirror and come back is T=L/(c-v)+L/(c+v). In the direction perpendicular to the motion, the time to reach the mirror and come back is calculated by solving (cT)^2=L^2+(vT)^2, so T=(L^2/(c^2-v^2))^(1/2). The experimental results did not match this calculation. Instead T was the same for both directions (T=2L/c )."

Alternatively, one can assume that, in accordance with Newton's emission theory of light, the velocity of the light, as measured by the observer, is c'=c±v, where v is the velocity of the light source relative to the observer. Suppose the apparatus passes the observer with velocity v. In the direction of motion, the time for the light to reach the mirror and come back is T=L/c+L/c=2L/c. In the direction perpendicular to the motion, the time to reach the mirror and come back is calculated by solving (c^2+v^2)T^2=L^2+(vT)^2, so T=2L/c. The null result of the Michelson-Morley experiment does match this calculation (for both directions T=2L/c).

Conclusion: In 1887 the Michelson-Morley experiment unequivocally proved that the speed of the light is c'=c±v, as predicted by Newton's emission theory of light, and refuted the assumption that the speed of light is independent of the motion of the light source.

Pentcho Valev