  An intriguing, and possibly significant, anomalous signal in the Brillet and
Hall experiment is contrasted with a simple first order test of special
relativity subsequently performed to discount that signal as spurious. Analysis
of the non-time-orthogonal nature of the rotating earth frame leads to the
conclusion that the latter test needed second order accuracy in order to detect
the effect sought, and hence was not sufficient to discount the potential cause
of the anomalous signal. The analysis also explains the results found in Sagnac
type experiments wherein different media were placed in the path of the light
beams.
