You can handle the heat, but what about the pressure? With a barometer, you'll always know what the air pressure is like. The very first barometer was simply a tube full of mercury, much like an open thermometer, which relies on the weight of air to push the mercury up the tube. The higher the pressure, the further the mercury rises. The mercury barometer was followed by the aneroid barometer, which relied on a metal cell enclosing a vacuum, which varied in size with the air pressure. Later on, barometers were even used as altimeters. Once their ability to predict the weather was understood, barometers became both tools and works of art. Vintage barometers make great display pieces, and many of them still work even today. They both serve a purpose and look great in your home. Mariners still use barometers, and you can even buy digital ones that fit in the palm of your hand. eBay sellers offer an assortment of antique or modern barometers. So the next time someone tells you the pressure is building when in fact it's dropping, you can tell them so.