Evangelista Torricelli was an Italian mathematician and physicist who was born in Faenza on the 15th of October 1608. In 1626 Torricelli went to Rome to study sciences and then later wrote a thesis on the path of projectiles. In the year 1641 he moved to Florence to assist the astronomer Galileo in his studies. (The Galileo Project, 1995)
Torricelli is most famous for his invention of the barometer which was built for the first time in 1644. While working with Galileo, Galileo suggested that mercury should be used instead of water. This was mainly because mercury is much heavier (roughly 14 times) than water and would not require the tube of the barometer to be ridiculously long. The barometer was created by first using a four foot tube and putting it upside down into a dish of mercury. As the tube was raised a vacuum was observed by Torricelli at the top of the tube (known as a Toricellian vacuum) (The Aneroid Barometer). The mercury stayed within the tube as he raised it higher out of the mercury and the mercury level in the dish dropped. Torricelli concluded that the weight of the air was pushing the mercury up into the tube instead of the vacuum holding it in there. Torricelli was the first of his time to state this and disproved that it was not by the ‘attractive forces’ of the vacuum that the mercury stayed in the tube. To disprove the common belief of the time, Torricelli compared the height that the mercury reached compared to that of water which was originally used for the experiment. It was found that the mercury only reached a fourteenth of the height that the water did, showing it was in fact the weight of the air pushing the substance up as mercury is roughly fourteen times heavier than water (Rubin, 2012).
He contributed to the understanding of gases by showing that gases do in fact have weight when most people believed them to be weightless. His barometer also gave science the understanding of gas pressure as the height that the mercury reached depends on the air pressure pushing down on it. The barometer that Torricelli invented was simply a four foot tube placed upside down in a dish of mercury. To allow the barometer to work the tube is simply raised until the mercury inside it does not rise any further. This maximum height that the mercury reaches determines the atmospheric pressure outside of the tube.
Torricelli is most famous for his invention of the barometer which was built for the first time in 1644. While working with Galileo, Galileo suggested that mercury should be used instead of water. This was mainly because mercury is much heavier (roughly 14 times) than water and would not require the tube of the barometer to be ridiculously long. The barometer was created by first using a four foot tube and putting it upside down into a dish of mercury. As the tube was raised a vacuum was observed by Torricelli at the top of the tube (known as a Toricellian vacuum) (The Aneroid Barometer). The mercury stayed within the tube as he raised it higher out of the mercury and the mercury level in the dish dropped. Torricelli concluded that the weight of the air was pushing the mercury up into the tube instead of the vacuum holding it in there. Torricelli was the first of his time to state this and disproved that it was not by the ‘attractive forces’ of the vacuum that the mercury stayed in the tube. To disprove the common belief of the time, Torricelli compared the height that the mercury reached compared to that of water which was originally used for the experiment. It was found that the mercury only reached a fourteenth of the height that the water did, showing it was in fact the weight of the air pushing the substance up as mercury is roughly fourteen times heavier than water (Rubin, 2012).
He contributed to the understanding of gases by showing that gases do in fact have weight when most people believed them to be weightless. His barometer also gave science the understanding of gas pressure as the height that the mercury reached depends on the air pressure pushing down on it. The barometer that Torricelli invented was simply a four foot tube placed upside down in a dish of mercury. To allow the barometer to work the tube is simply raised until the mercury inside it does not rise any further. This maximum height that the mercury reaches determines the atmospheric pressure outside of the tube.
A sample problem illustrating Torricelli’s work would be the use of a barometer in meteorology. If for example a prediction was needed for the upcoming weather conditions a barometer could be used by taking a reading on an average sunny day and comparing it to each following day. If the height of the barometer is the same as the first reading then a prediction can be made that the day will be similar to the first one. If the barometer rises or drops then a weather change can be predicted such as rain or wind. This is because the low and high pressure fronts that move around the world are indicated in the mercury level of the barometer, and depending on the height a prediction can be made.