What Is This Wall Hanging Glass

Any idea what is this for? It has opening only at the spout.

 

looks like a barometer

 

Agreed, it's a barometer, you put water in it and as the barometric pressure goes up and down, the water in the tube rises and falls.

https://sciencemanuals.wordpress.com/2015/03/03/test-blog-2/

 

Its blue from food coloring so you could see the water easier.

 

Thanks.

 

Hi,
It had a black iron hanger with a small round base to collect water from when the outside pressure was low. The water would drip out the stem. I keep mine filled with clear vinegar with a couple of blue drops from cake frosting kit. It keeps it from staining the glass.
greg