Decided variations either above or below normal are highly important symptoms. A temperature below 98° is called subnormal, and one above 99.5° is called fever. The number of degrees of fever does not necessarily bear a direct relation to the severity of an illness. Thus, it does not follow that one person is twice as sick as another, because his temperature is twice as many degrees above normal. All symptoms, including variations in temperature, must be considered in connection with one another, and it is generally impossible to state the significance of any one symptom taken by itself. The temperature should be taken once or twice a day as a matter of routine in almost every form of illness, and oftener when the patient's condition requires it. Also it should be taken as a matter of routine whenever there is indication of beginning sickness; especially when there is headache, pain, sore throat, coated tongue, cough or cold, chill, vomiting, diarrhœa, or rash. It is not a good plan to take one's own temperature oftener than necessary, or indeed anyone's; certainly not a baby's, since frequent use of the thermometer may irritate the rectum. PULSE.--Each time the heart beats, blood is forced out from the heart into the arteries, thus causing an expansion of the arterial walls. This expansion, called the pulse, can be felt in some places where arteries lie close to the surface of the body. The character of the pulse beat and its rate, or the number of times the beat occurs each minute, give information about the heart and blood vessels; taken together they are perhaps more important than any other one symptom. [Illustration: FIG. 11.--TAKING THE PULSE AT THE WRIST. NOTE THE POSITION OF ARM. (_From "Elementary Nursing Procedures," California State Board of Health._)] The pulse rate varies much more than the temperature. It differs in different individuals and at different ages, and it often shows great temporary changes, especially during exercise or eating, or as a result of excitement, fear, or other emotion. Definite statements in regard to normal pulse rates are hard to make, because different individuals though in perfect health show marked variations; we generally say, however, that the pulse rate of a normal man at rest is about 72 a minute, and that of a normal woman is about 80 a minute. At birth the pulse is quickest; it may then be from 124 to 144. From the 6th to the 12th month it may be from 105 to 115 a minute, and from 90 to 105 between the 2d and 6th years. About the time of puberty it reaches the adult rate, and during old age it may be decidedly slower than the adult rate. What we chiefly want to know about the pulse is 1. Its rate, or number of beats per minute, 2. Its force,--whether weak or strong, 3. Its rhythm,--whether regular or irregular.