Dad's De Ville back from service today!
Thanks to @shane0mac and the gang at European Watch Co in Boston.
More pics and details will eventually come @hijack in a separate thread.
The Bivouac's barometer got a workout on the flight home.
Waiting to take off, at 765 mmHg.
Cruising altitude of around 30,000 feet, at 577 mmHg. If I had thought to set the bezel properly, the cabin pressure would have registered as the pressure at an altitude of roughly 8,000 feet.