[en] If the West-East speed of a laboratory, owing to its rotation about the Earth's axis (some 350 m/s at 40₀N), shows up in speed-of-light anisotropy measurements confined within the laboratory, then it is submitted that this would clearly refute Einstein's theory. Given such an experimental result, test apparatus otherwise fixed to the Earth and so constrained to share its acceleration, could, in principle, be replaced by similar aparatus caused to rotate once a day in the opposite sense and subjected to vertical acceleration of approx. 3 cm/s₂ for test periods commensurate with the small time it takes for light to traverse an optical test circuit. Such an applied motion will ensure that the system is compensated to satisfy the zero acceleration requirement of Einstein's hypothesis. Now, there is no logical way in which one can argue that the 350 m/s detection can be eliminated owing to these acceleration effects. On the contrary, the logic of relativity argues that the 350 m/s speed cannot be detected in either situation. The laws of physics and speed-of-light measurements have to be the same for systems in relative non-accelerated motion. If 350 m/s difference in light speed is sensed and this cannot be connected with gravitational acceleration at the Earth's surface or the Earth's centrifugal acceleration without dependence upon Earth radius, then Einstein's theory stands disproved. (Auth.)