Who Invented the Barometer — Reading Comprehension

The concept of atmospheric pressure, the weight of the air that surrounds us, was not always understood. For centuries, people believed that a vacuum could not exist and that water pumps worked because "nature abhors a vacuum." This idea, however, could not explain why a pump could only raise water to a maximum height of about 10 meters. The answer to this puzzle was discovered by Evangelista Torricelli, a brilliant Italian physicist and mathematician who was a student of the famous Galileo Galilei. In 1643, Torricelli created the first-ever barometer, a device that could measure the pressure of the atmosphere.

Torricelli's invention was a simple but groundbreaking experiment. He took a long glass tube, sealed at one end, and filled it completely with mercury. He then inverted the tube and placed its open end into a basin of mercury. He observed that the column of mercury in the tube did not completely fall out. Instead, it settled at a specific height, leaving an empty space, or Torricellian vacuum, at the top of the tube. Torricelli correctly deduced that the pressure of the surrounding air pushing down on the mercury in the basin was what held the mercury column up inside the tube.

The height of the mercury column was a direct measure of the atmospheric pressure. A higher column meant greater pressure, while a lower column indicated less pressure. This groundbreaking discovery proved that air has weight and that atmospheric pressure is a quantifiable force. Torricelli’s mercury barometer became the standard for measuring air pressure for centuries. Today, we use various types of barometers, including more portable aneroid barometers, which use a sealed, flexible metal box instead of liquid mercury.

Barometers are essential tools in modern life, particularly in the field of meteorology. By tracking changes in air pressure, meteorologists can forecast weather patterns. A rapid drop in pressure often signals an approaching storm, while a steady rise suggests fair, clear weather. Pilots also rely on barometers to determine their altitude, as air pressure decreases at higher elevations. The invention of the barometer fundamentally changed our understanding of the atmosphere and paved the way for modern weather science.

Fun Fact: The unit of pressure "torr" is named in honor of Evangelista Torricelli. One torr is equal to about 1/760 of an atmosphere, a value derived from the average height of the mercury column in Torricelli's experiment.

Who is credited with inventing the first barometer?

What did people believe before the barometer was invented about why water pumps worked?

What liquid did Torricelli use in his famous experiment to demonstrate atmospheric pressure?

What is the name of the empty space that formed at the top of the inverted tube in Torricelli's experiment?

A rapid drop in barometric pressure is often a sign of what weather condition?

Why did the mercury column in Torricelli's experiment not completely fall out of the tube?

Which of the following best describes the main idea of the passage?

If a pilot is flying and their barometer shows a decreasing pressure reading, what is likely happening?