Although most of us know about the 'Rig for Red' issue.
It was not always so...
Check this out:
http://img176.imageshack.us/img176/8075/blue1nq8.jpg
This picture shows you one of the interior red lights of the USS Cod in Cleveland, Ohio.
As you can see it reads BLUE on the casing. Somewhere in time it was thought that blue light had the effect as described for red light. After experiments it was found that red light was better. So, you see that even something simple as rig-for-red had to be 'invented'. It was RIG FOR BLUE at one time
groetjes,