Thermometer how to shake can not shake down, this time should consider the thermometer is bad, should be replaced with a new thermometer. The principle of mercury thermometer is thermal expansion and contraction, it is the use of temperature so that the mercury column rises, generally recommended that the armpit temperature shall prevail, in the middle of the armpit clamping 5-10 minutes can be derived from the value of human body temperature. Half an hour before the temperature measurement, it is best not to drink, eat, activities or bathing, because these factors may lead to high body temperature, in the measured body temperature should be placed in a horizontal position, read out the value of the mercury end is the measured body temperature.