Why is there a mirrror on pipe organs?

Answer 1

Organist's use the mirror when they are playing in a church service to see the congregation and the minister. This allows them to see physical cues on when to start and stop playing. A good example of this is when playing for the offertory. It allows the organist to see when it is completed and allows them time to find a good ending point if they are in the middle of a song.This is the case because often, the console is positioned so that the organist is facing away from the audience.