1950's Blown Glass Swan Ambient Weather Barometer 7.25" Tall. What you do is fill it with a couple of inches of water so it is up to the fill hole and then maybe put some food dye into the water and as the barometric pressure goes up, the colored water will rise up the neck of the swan. I believe I have that correct, but you will want to verify. Very delicate thin glass that makes these vintage one's very hard to find because they break easily. Would be a great gift for a weatherperson, teacher or for children. I have 2 of these available, sold separately.