What is the Meaning & Definition of thermometer

Is designated by the term of thermometer to that instrument which is used to make and measure the temperature, either at the behest of ambiance, of a region or body temperature observed human at some point.
Thermometer, all instruments created back far in time that they still enjoy an absolute popularity and use, one of which has undergone further evolution and is crossed, done that needs to be proved and tested, with the recent emergence of electronic thermometers, digital.
In its early days, the thermometer was made taking advantage of the phenomenon of the expansion, therefore, for their production have been always used those materials that have a high coefficient of expansion, in such a way that by increasing the temperature, stretch that could occur is easily visible and appreciable. Then, the base metal used in the manufacture of thermometers was mercury, enclosing it in a glass tube to which was incorporated a graduated scale whereby the temperature of things or people could be determined.
The history of the thermometer is the thermoscope, created in the year 1592 by Galileo Galilei. It consisted of a glass tube that ended with a closed sphere form, open end was which dipped are mouth down into a mixture of alcohol and water, for example, while the mentioned sphere remained on the other side, at the top, then, when warming liquid, this went through the tube and marked temperature. Then, the invention of Galileo Galilei, the graduated scale would be added with and as well the thermometer would be created as we know it today.
There are different types of thermometers that will be differentiated among themselves by the scope in which they are used and what are responsible for measuring, among them, the most famous, the thermometer's mercury (used in medicine to measure the body temperature of individuals and determine if they have fever or not), the pyrometer (used in foundries and glassworks) , gas (used to calibrate other thermometers), bimetallic (used as a temperature sensor), thermocouple (used at the behest of the welding of metals), balloon (measure radiant temperature), wet-bulb (measures the influence of moisture on the thermal sensation) and the maximum and minimum thermometer (used in meteorology).