The mercury barometer was first discovered by the Italian Evangelista Torricelli in 1643 and has been since then known as the Torricelli barometer. The principles on which the Torricelli aka the mercury barometer is based date since the time it was first discovered in the 17th century. Those principles although more than 300 years old are still the ones that stand at the base of a modern mercury barometer. By now you might be asking yourselves – so how does a mercury barometer work ? and I’m frankly glad you asked because we have the explanation ready.
How a mercury barometer works
The principles on which the barometer works can be easily illustrated as follows: take one long glass tube that is sealed at one end and then fill it with liquid mercury metal. Turn the filled tube upside down and place it in a bowl filled with mercury – also known as a cistern. When turning the tube upside down a bit of mercury will leak into the cistern and leave a vacuum at the top of the tube making our mercury barometer a real life example. What will happen next is that air pressure will start pushing down on the mercury in the cistern which will at its turn push up with an equal pressure on the mercury in the tube making the mercury in the tube go up or down, thus indicating the exact air pressure in the surrounding environment. Under normal circumstances, the column of mercury in the glass tube stands at a height of about 30 (29.92) inches (75 centimeters) when measured at sea level. An explanation of the above is pictured below for an easier understanding.
mercury barometer picture
So to recap here’s what you have to do to get a working mercury barometer: take one tube and fill it with liquid mercury, take a recipient – anything that resembles to a can and it’s water tight – and fill that one with liquid mercury as well. Turn the tube upside down and place it in the cistern. Wait 5 minutes and measure the height at which the mercury column stands in the tube and that’s the air pressure in the surroundings.
If you find barometers interesting you might want to consider purchasing a mercury barometer. There are various places where you can successfully buy mercury barometers at reasonable prices and in good standing. Ebay and Amazon are just a few of the big names where you could easily purchase an antique mercury barometer. A specialized place where you could also get more information on antique mercury barometers is Charles Edwin’s place where he showcases some of the nicest antique mercury barometers.
Although I don’t really emphasize on purchasing an used barometer because of the healthy risks they poses as a last alternative you could resort to this and purchase a used barometer and stay on the cheap side.
