The word “thermometer” comes from Greek, and thermos means “hot” while metron means measure.

Thermometers are used for especially engineering and scientific applications of measuring temperature.

Galileo Galilee invented the first modern day usable thermometer (thermoscope) even though the Greeks used simple versions of them to measure heat and cold earlier.

In 1596, Galilee invented the thermoscope that actually indicates the actual temperature by showing a difference in temperatures.

Therefore, his thermoscope showed if the temperature was lower, higher or the same but the actual difference could not be recorded.

Gabriel Fahrenheit invented the first reliable mercury thermometer in 1714 and his thermometer is still used today.

Fahrenheit also lent his name to the measurement of temperature (OF) which is universally accepted today so that there is agreement and consistency in measurements.

In 1742, Anders Celsius a Swedish inventor suggested that 0 be taken as the boiling point, and 100 be taken as the freezing point.

The Celsius scale was invented the next year, which used this measurement method, and this too is widely accepted today.

In 1848, Lord Kelvin of Scotland proposed another measurement where 0 is considered the lowest temperature.

According to this, 1 Kelvin (degree) is equal to 1 Celsius (degree). The Kelvin method is also used in some thermometers today.

When indicating temperature levels most the Fahrenheit measure and its equivalent Celsius grade are mentioned to make things clearer.

Besides these key figures that invented and improved the thermometer, there were others too that contributed in large and small ways to make it what it is today.

The thermometer uses different principles to measure the heat, such as temperature sensors (the bulb of mercury at the end), and a way of converting this change (the amount the mercury rises) into numbers.

Today’s thermometers are made from either alcohol or mercury and they measure the temperature of the air. They are the most reliable of thermometers.

The alcohol or mercury rises according to the amount of amount the air expands. So the reading is taken at the amount the alcohol or mercury rises.

Another type of thermometer is the ‘expansion thermometer’. This has different metals that expand and contract according to the air expansion.

The two metals are wound together like a spring. So according to the changes in the temperature, these two either unwind, or wind up tight.

A needle is connected to the spring, which moves according to the movement of the spring so that a reading can be taken.

Besides these two varieties, there are many other types of thermometers used for different purposes.

Some of their applications are on roadways to gauge if icing conditions are there, in air conditioners, freezers, heaters, refrigerators, and water heaters.

They are also used in airports, weather centres, hospitals, space stations, nuclear power facilities, and in the food industry.

It is difficult to think that the thermometer that we use at home to check if we are running a fever has such a colourful history.