New answers tagged observation
I ended up finding this on page 14 of the Edmund Scientific Holiday Sale catalog, with sale ending on December 31, 1983: except that it's "Planetimer" (and not "Planet-timer"), catalog number H9454. A 1200dpi image somewhat shows how it's supposed to work: My original question was going to be: could this device have worked? I would also appreciate ...
Top 50 recent answers are included