Mercury expands on heating and contracts on cooling. We can place the thermometer in the mouth under the tongue or in the armpit for about one minute. The expansion of mercury along the scale gives us the temperature of the body.
Man has been increasing his knowledge by observing and exploring his own environment. Earlier, people did not know or understand the nature of diseases. He has discovered many secrets about his health. He has learnt about the causes of various diseases. Many diseases have been brought under control, and a few have been eradicated. Thus, today man leads a healthier and longer life. Many instruments have been developed in different parts of the world, which help to bring diseases under control.
The normal temperature of our body is 98.4°F. Sometimes it rises because a person suffers from a disease. We say that he has fever. In ancient times we learnt about the fever and the disease by touching the body or by feeling the pulse. G. Daniel Fahrenheit developed in 1715 a simple instrument, called the clinical thermometer. The scale marked on it generally shows the range between 95°F to 110°F. This instrument is filled with mercury.
Mercury expands on heating and contracts on cooling. We can place the thermometer in the mouth under the tongue or in the armpit for about one minute. The expansion of mercury along the scale gives us the temperature of the body. The exact and proper recording to temperature helps the doctor to treat the patient accordingly. This instrument is very useful for the doctors.