Thermometers are often seen in our life, but they can be divided into many kinds according to different environments. The most common ones are bimetal thermometer, pressure thermometer and glass rod thermometer.

For bimetallic and pressure thermometers, the data should be read with the observer's line of sight vertically aligned with the scale value indicated by the pointer tip。When the temperature is measured with a glass bar thermometer, the scale corresponding to the concave or convex surface of the liquid column shall be taken as the reading when reading the data due to the capillary phenomenon of the liquid in the tube.