The Mars and Gyralights had very similar mechanisms. The Gyralight mechanism had one pivot off the drive motor which made it trace a circular or oval pattern. The Mars Light had an additional pivot and arm that introduced the additional movement that made the figure 8 pattern. Additional pivots could be added to create additional movement such as fire trucks had. I have seen one Mars Light in a locomotive application that had 3 pivots so the pattern crossed itself twice in the course of tracing a circle. The more pivots the more moving parts that needed to be maintained (and were potentially subject to failure) which I think explains the popularity of the Gyralight in later years on RR's that desired a signal light.

99