I seek information in relation to my attempts to understand an aspect of special theory. I recently read the comment - "SR says that the measured speed of light is constant." In his book 'An Introduction to the Special Theory of Relativity' Robert Katz asks (36, Affiliated East-West, 1964) - "Is the moving rod really contracted in its direction of motion? Is time really dilated? These questions depend on what is meant by 'really'. In physics what is real is identical with what is measured." In his article 'The Twin Paradoxes of Special Relativity: Their resolution and Implications' S J Prokhovnik wrote (548, Foundations of Physics, Vol 19, No 5, May 1989) that (in space) light travels isotropically away from its source but that if an observer is moving past that source it's emissions will not be isotropic relative to him however on page 550 Simon points out "It is well known that the contraction effect is sufficient to conceal the light-speed anisotropy [from that observer]. Is this correct? Does the idea that his rule is contracted conceal the light's anisotropy relative to the moving observer ergo he measures it to be c?