  Historically, the Michelson-Morley experiment has played a crucial role for
abandoning the idea of a preferred reference frame, the ether, and for
replacing Lorentzian Relativity with Einstein's Special Relativity. However,
our re-analysis of the Michelson-Morley original data, consistently with the
point of view already expressed by other authors, shows that the experimental
observations have been misinterpreted. Namely, the fringe shifts point to a
non-zero observable Earth's velocity v_obs = 8.4 +/- 0.5 km/s. Assuming the
existence of a preferred reference frame, and using Lorentz transformations to
extract the kinematical Earth's velocity that corresponds to this v_obs, we
obtain a real velocity, in the plane of the interferometer, v_earth = 201 +/-
12 km/s. This value is in excellent agreement with Miller's calculated value
v_earth = 203 +/- 8 km/s and suggests that the magnitude of the fringe shifts
is determined by the typical velocity of the Solar System within our galaxy.
This conclusion, which is also consistent with the results of all other
classical experiments, leads to an alternative interpretation of the
Michelson-Morley type of experiments. Contrary to the generally accepted ideas
of last century, they provide experimental evidence for the existence of a
preferred reference frame. This point of view is also consistent with the most
recent data for the anisotropy of the two-way speed of light in the vacuum.
