https://www.reddit.com/r/UnresolvedMysteries/comments/4hq4o1...

Seems likely that Robert Truman Hungerford has been placing these ads himself for the last 45 years, as a kind of solitary practice. He is apparently now giving hints to their interpretation (http://www.maydaymystery.org/mayday/texts/25-dec7.html): "Good starting point: Historically, what sort of compass is in the picture?"