Thermometers are found everywhere these days.This medical instrument, however small and simple it might look, saves lives on a daily basis. It is worth exploring how thermometers came into existence and some of the unknown facts about them.History Of ThermometersA thermometer is a simple device that is used to measure the temperature of an object or a living animal. People are able to tell how hot or cold something is by reading these measurements. A significant temperature change usually indicates that something is wrong. Thermometers have been around for several centuries. Over the years with the improvement in technology, their usage and accuracy have improved significantly.The first attempt to create a device that could measure temperature was by Galen, a Greek physician, in 170 AD. Almost all of his attempts failed.In 1593, Galileo Galilei invented a water-based rudimentary thermoscope that could measure temperature variation. This device is called the ‘Galileo Thermometer’, even though it was a thermoscope.The difference between the two is that while a thermometer has calibration, a thermoscope does not.Calibration was added to the thermoscope by Santorio Santorio, an Italian physiologist, in 1612. Santorio invented the first-ever thermometer.In 1654, Ferdinand II, Great Duke of Tuscany, created the first sealed liquid-in-glass thermometer. Although he was successfully able to fill alcohol inside the glass, the measurements were inaccurate.In 1701, Danish astronomer Olaus Romer decided to calibrate the temperature scale relative to the boiling point of water.The first mercury-based thermometer was invented by Gabriel Fahrenheit. He introduced the Fahrenheit scale in 1714 and this was the most accurate thermometer up until this point. The Fahrenheit scale is named after him.In 1731, French entomologist René Antoine Ferchauld de Réamur invented the Réamur scale.In 1742, the Celsius scale was invented by Swedish inventor Anders Celsius.The absolute temperature scale or Kelvin scale was invented by Sir William Thomson in 1848.The first clinical thermometer was invented in 1866 by Thomas Clifford Allbutt.Types of ThermometersThere are different types of thermometers that are designed for a specific purpose in mind. Some thermometers were designed to be more accurate or more convenient to use than their predecessors.All thermometers can be broadly classified into laboratory and medical thermometers.Laboratory thermometers are used in lab settings and are highly accurate in their readings. They have longer stems compared to their medical counterparts.The oldest type of thermometer is the mercury-based thermometer, also known as the liquid-in-glass thermometer. This thermometer provided accurate readings and was used orally, rectally, or underarms.Since mercury is a hazardous substance that can leak when glass breaks, mercury thermometers are no longer in use.The next oldest type of thermometer is the digital thermometer. This thermometer has in-built heat sensors that can detect body temperature.The main benefit of using a digital thermometer is it takes less than a minute to read the temperature. A mercury-based thermometer took three to four minutes to do the same.A digital thermometer can be used orally, rectally, or placed under our armpits.Tympanic thermometers or digital ear thermometers are meant to be placed in the ear canal for measuring temperature.Tympanic thermometers are equipped with infrared rays that provide fast and accurate readings.Forehead thermometers or temporal thermometers are handheld devices and are able to read temperature within seconds.Forehead thermometers do not require any physical contact to measure temperature.Oral thermometers can be based on mercury liquid or digital technology. These are the most accurate type in both children and adults.Digital thermometers are the most common types of thermometers used. These thermometers do not have calibration, but display temperature readings on a digital screen. A modern thermometer can display both celsius scales and fahrenheit scales.Uses Of ThermometersDifferent types of thermometers have specific uses. They cannot be used interchangeably, at least not with accuracy.A clinical thermometer is used to measure the temperature of a human body. Whether it be mercury thermometers or digital thermometers, if they are designed for clinical use, they must be able to read temperatures.Laboratory thermometers are used to measure the temperature of any substance in the lab. They usually have more range compared to clinical thermometers. In extreme cases, they also measure the boiling and freezing point of a liquid.Industrial thermometers are used to measure the temperature of a multitude of objects that can range from -76-932F (-60-500 C).The majority of industrial thermometers are infrared thermometers and the temperature is measured from a distance.Scientists have also invented app-based thermometers. These use a digital thermometer for reading temperature that link back to a mobile app. These apps are used for measuring the temperature of the environment rather than people.Fun Facts About ThermometersThermometers are medical devices that most people do not have to use on a day-to-day basis. This means you may not many of the facts about them. Here are some fun facts about thermometers that you should know:A thermometer consists of several components like the tube, bulb, and stem. The tube doesn’t exist in a digital thermometer.The very first thermometers invented contained water in them rather than mercury. However, water freezes at 32 F (0 C) so inventors switched to mercury and alcohol.Thermometers with liquids were based on a simple principle. When heat was applied to the liquid, it expanded and indicated a rise in temperature.A digital thermometer is based on sensors that detect changes in temperature.Digital thermometers were invented because people with a cough or patients who were vomiting could not hold mercury-based thermometers in their mouths.Rectal thermometers are usually more reliable than oral thermometers since there are less influencing factors.There are thermometers specifically meant for toddlers known as pacifier thermometers. Babies can keep in their mouths like a teat.Today’s modern thermometer can measure multiple temperature scales, like degrees celsius, degrees fahrenheit, and even degrees Kelvin.
Thermometers are found everywhere these days.
