In the first place we will proceed to determine the etymological origin of the term thermometer that now concerns us. In this sense we can establish that it is composed of two clearly defined words: the Greek word thermos, which can be translated as "hot", and the Greek term metron, which stands for "measure."
A thermometer it is an instrument that allows measuring the temperature . The most popular consist of a glass bulb that includes a small capillary tube; It contains mercury (or other material with a high coefficient of expansion), which expands according to the temperature and allows it to be measured on a graduated scale.
He thermoscope what Galileo Galilei invented in 1592 It is considered as the predecessor of the thermometer. This device had a hollow glass ball and a tube welded to it and allowed to measure changes in temperature from the contraction or expansion of a mass of air.
When incorporating the numerical graduation to the thermoscope, the thermometer emerged. In 1714 , Gabriel Fahrenheit He created the mentioned mercury thermometer. This scientist is also the creator of the Fahrenheit thermometric scale , which became the unit of temperature in the Anglo-Saxon system of units. The most common scale, anyway, is Celsius , baptized in honor of Anders Celsius .
He pyrometer On the other hand, it is a thermometer that allows you to measure the temperature of a substance without being in contact with it. It is based on the distribution of thermal radiation.
However, there are many other types of thermometers. Thus, for example, we find the digital ones that are the ones that have become the most used in homes since they are simple, fast and do not contaminate. This last reason is explained by the fact that they do not contain mercury inside.
In the same way, we cannot ignore the existence of clinical thermometers. These can be of two kinds, digital or mercury, and are those used in different health centers to measure the body temperature of patients.
To all these we could add the maximum thermometers, which are responsible for recording the maximum temperatures; those of minimums, which do the same with the lowest temperature; and the differentials. The latter are used to carry out the measurement of what are small temperature differences.
There are also kitchen thermometers that are very useful because they serve to determine the temperature at which certain foods are found. This will help us, in many cases, to know if a dish that we have made needs to be in the oven longer or is already in the right place.
There are other types of thermometers that work from electrical resistance, electromotive force or the changes that a gas undergoes, for example.
Thermometers have multiple uses. The wide variety of instruments has its logic according to the different uses of the device. There are thermometers that are used in industrial production and that must withstand very high temperatures. The classic mercury thermometers, on the other hand, are used to take the fever .