The mercury thermometer usually measures five minutes. Before using the mercury thermometer, you need to shake the mercury column to below 35°C, then place the mercury end of the thermometer at the very top of the armpit, which is deep in the armpit, and clamp the thermometer with your upper arm to avoid dislocation and falling off. After five minutes of measurement, remove the thermometer, read the temperature data and then wipe it clean with toilet paper for next time or for others to use. To read, hold the end of the thermometer with one hand, that is, away from the end of the mercury column, so that the eyes and the thermometer at the same level, and then slowly turn the thermometer, from the front to see a very thick column of mercury, you can read the corresponding temperature value. When reading, do not touch the water temperature end of the thermometer with your hand, this will affect the mercury column, and cause inaccurate measurement.