To measure temperature, we need an instrument called a thermometer. There are several types of thermometers, namely the Galileo thermometer and the infrared thermometer. You can see the Top 5 Best Galileo Thermometers [2021 Review] – WeatherStationProfy to get the best suitable for you. In this discussion, we will thoroughly explore the two thermometers, as for the explanation as follows.

Galileo’s thermometer is a thermometer made of mercury placed in a glass tube. A calibrated mark on the tube allows the temperature to be read according to the length of the mercury in the beaker, varying according to temperature. To increase accuracy, there is usually a mercury bulb at the end of the thermometer which contains some of the mercury, expansion, and contraction of the mercury volume are then continued into the narrower part of the tube. The space between the mercury can be filled or left empty.

As a substitute for mercury, some family thermometers contain alcohol with added red dye. This thermometer is safer and easier to read. A special type of mercury thermometer, called a maximum thermometer, works by having a valve in the neck of the tube near the bulb. As the temperature rises, the mercury is pushed up through the valve by the expansion force The reader can then read the maximum temperature for the specified time. To restore its function, the thermometer must be swung vigorously. This thermometer is similar in design to a medical thermometer.

Mercury freezes at -38.83ºC (-37.89ºF) and can only be used at temperatures above it. Mercury, unlike water, does not expand when frozen so it does not break the glass tube, making it difficult to see when it freezes. If the thermometer incorporates nitrogen, the gas may rush down into the column and be entrapped there as the temperature climbs. If this occurs the thermometer cannot be utilized until it returns to its initial condition. To avoid this, the mercury thermometer should be placed in a warm place when the temperature is below -37ºC (-34.6ºF).