OK, this isn't a Klein Bottle. It's a weather glass barometer. The height of the colored water in the side tube changes with barometric pressure (and local temperature).

When barometric pressure increases, the water level in the side tube moves down. On those low pressure days, the water moves up. Neat!

The curved glass tube is open at the top. Pour some water into the tube, along with a couple drops of food coloring. The level of water in the side tube will then reflect the local air pressure and temperature. If you wrap your hands around the spherical reservoir, you'll warmthe trapped air; as it expands, the water in the side column will rise.

The physics behind this was developed by Torricelli around 1643. He showed that atmosphereic pressure can support a 10 meter water column ... and that air pressure varies with weather.

You're right - this isn't precisely calibrated. And there's no high-tech solid-state gyrometric detectors - this uses technology that's over three centuries old. Don't ask for large quantities of these: I have a half dozen, left over from a glass shop that closed, due in part to the overhead of unprofitably making Klein Bottles. (note- as of Sept 3, 2010, I have only one left. When it's sold, I will remove this entire page from the web.)

Normally, you'd expect to pay $31 for such a high quality, hand blown glass barometer. But thanks to Acme's foresight (and the closure of a glass factory), you can have one of these for a mere $30 ... a good value compared to the typical public lottery.

• - Height 190mm (7.5 inches)
• - Diameter 120 mm (4.5 inches)
• - Diameter of sphere is 100 mm; volume is a little over a half litre.
• - Weight: 140 gm (5 oz)

   

Like ACME's fine Klein Bottles, this is handcrafted from pure Borosilicate Glass ... Pyrex, Kimax, Bomex, or Simax. It has a bulk density: 2.23 gm/cm3 and expands just 0.000326% per degree C. This means that it'll shrink only a few microns when you trek from Tucson to Nome. Nor should you worry about it dissolving -- we've tested samples in water, acetone, methyl-ethyl-ketone, maple syrup, and jello.