Antique Union Barometer by Currier & Simpson 1860 - Rare!

Rare Union Barometer by Currier & Simpson pat'd date Jan 31, 1860. This is an antique American version of a tendency barometer which would have used mercury instead of a red liquid used today. Bottom knob is used to slide thermometer scale up and down so that thermometer reading matches mercury level. The barometer reading is then displayed on the vernier scale between "Rain" and "Fair". This is the only one I have ever come across in my 25+ years collecting / dealing in antique barometers. Missing mercury in tube. Measures 16" by 5" by 2".