{Weird double post alert - sorry!}
This is a watch I picked up for $20. It turns out to be a seiko 6139-6022, a "Pulsations" model chronograph.
This is a somewhat unusual model, reportedly meant for doctors. You start the chronometer, count 10 pulse beats, stop the chronometer, and the log base 10 bezel tells you the patient's pulse.
All straightforward enough. But here is something I do not understand. The bezel can be rotated by turning the watch stem. Why?!? What function is served by being able to re-orient the bezel? The chronometer hand always flies back to 12 o'clock when you press the reset button. Why would the bezel ever need to be oriented anywhere else?
I would be very interested in an answer. I've been searching various vintage watch sites, with no luck.
The watch works fine, by the way. Appears to lose about 30 seconds in two days, which is more than acceptable in my book. I mean, it was only $20. Tells time AND gives me that "cheap bastard chic" frisson. I've also been assured that a grubby old Seiko makes me firmly non metro you know ual