This one is my first ‘hummer’ — an Accutron. It has a battery, but unlike a quartz watch, the charge from the battery ‘excites’ a tuning fork to oscillate at a constant frequency. Hence the watch ‘hums’ rather than ticks. Very cool technology for 1960. And unlike a quartz watch, the second hand sweeps smoothly rather than in one-second jerks.
1968 Bulova Accutron 218 Deep Sea
This Accutron was made in 1968 (it has an ‘M8’ date code on the back). It uses the 218 calibre movement, the second iteration of the Accutron following on from the 214.
When new it was a professional diving watch, waterproof to 666 feet — but nowadays I’d be reluctant to get it wet until I have the seals replaced and the case pressure-tested.
The case and dial are in very good condition but the bezel is showing its age, as are the hands. I love the red-on-silver date and the domed crystal with cyclops magnifier *under* the uninterrupted curve (why didn’t Rolex think of that?)
Tim's Watch Blog 
Thanks so much for your sharing!