Recently back from a 8-day vacation in Dubrovnik, Croatia.
If you watched Game of Thrones then this place is a must see (I'm one of ten on the planet that didn't watch the series). Got to visit many museums and one on the list was the Maritime museum. Leave it to a meteorologist to zoom in on the barometers. As you know, barometers have been replaced by electronic wizardry. The pics are barometers from ships of yore that sailed the Adriatic sea. The barometer ranges from 28 inches of mercury to 31 inches just like a pilot's basic altimeter. The words inscribed on the face are Italian ranging from Tempesta (storm) at 28" to Molto Asciutto (very dry) at 31". You will no longer find inches of mercury used when you fly abroad. It's been replaced with hectopascals referenced as QNH.
Chapter 4 has a great write up on atmospheric pressure and chapter 21 addresses altimetry.