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|| MAKING A FANCY BAROMETER
Here's a really fancy barometer. Remove the cork from a small thermos bottle. Drill a hole through the cork, just large enough to insert a plastic straw or glass tube. Seal the cork in the thermos bottle by dripping candle wax all around the cork where it enters the thermos.
Mount the thermos upside down on a stand so that the end of the tube is about 1/4 inch from the base of the stand. Wrap the thermos in rock wool or some other insulating material and fit a cardboard box snugly around it.
The insulation will help to keep the instrument from acting more like a thermometer than a barometer. (What is the difference?)
Now color some mineral oil with food coloring. Listen to the radio weather report, and on a day when the air pressure (barometric pressure) is going to be low (the low should be below 29.30 inches), we'll experiment with our barometer. Set a cup of the colored mineral oil beneath the tube.
If you take an occasional look at your barometer, you will see that when the air pressure rises, the mineral oil is pushed up the tube.
A scale can be placed behind the tube so that changes can be noted numerically.
If you remember from previous barometer activities, this instrument will work indoors as well as outdoors, since the air pressures are about the same.
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