When I was growing up, my dad and I sometimes went on road trips. To visit family mostly, which meant going to or through New Jersey. And there was one rest stop we would always brake for. This rest stop had a machine that read your Biorhythms! You would put in a quarter or 50 cents, enter your information, and you would get a printout like the one above. The science of Biorhythms actually goes back to the turn of the 20th century, and was of great interest to Freud while he was developing his psychoanalytic concepts. The back of the card explained how to read your Bio-chart. I wish I could find a snapshot of the machine itself. When it was calculationg your Bio-chart it made this great bleepy calculate-y noise. Sometime in my late teens, maybe when we were visiting colleges, the machine was no longer at our regular pit stop. I found this Biorhythm while I was cleaning out my closet to bring out the winter clothes....

There's a beautiful book explaining Biorhythms here:

Or you can get your own Biorythm readout by downloading a program for your PC (note: it's Windows only so I haven't tried it and I can't vouch for it's worth or if it even works at all). You can also try entering your data on this one for a quick readout.