=HEADACHE FROM VARIOUS CAUSES.=--It is impossible to decide from the location or nature of the pain alone to what variety of headache it belongs, that is, as to its cause. It is only by considering the general condition of the body that such a decision can be attained. =Headache from Indigestion.=--The pain is more often in the forehead, but may be in the top or back of the head. The headache may last for hours, or "off and on" for days. Dull headache is seen in "biliousness" when the whites of the eyes are slightly tinged with yellow and the tongue coated and yellowish, and perhaps dizziness, disturbances of sight and a feeling of depression are present. Among other signs of headache due to indigestion are: discomfort in the stomach and bowels, constipation, nausea and vomiting, belching of wind, hiccough, and tender or painful eyeballs. In a general way, treatment for this sort of headache consists in the use of a cathartic, such as calomel (three-fifths of a grain) at night, followed by a Seidlitz powder or a tablespoonful of Epsom salts in a glass of cold water in the morning. A simple diet, as very small meals of milk, bread, toast, crackers with cereals, soups, and perhaps a little steak, chop, or fresh fish for a few days, may be sufficient to complete the cure. =Sympathetic Headaches.=--These are caused by irritation in various parts of the body, which is conveyed through the nervous system to the brain producing headache. Headache from eye-strain is one of this class, and probably the most common, and, therefore, most important of all headaches. There is unfortunately no sure sign by which we can tell eye-headaches from others, except examination of the eyes (see p. 29). Redness, twitching, and soreness of the eyelids, and watering of the eyes, together with headache, after their excessive use may suggest the cause in some cases. The pain may be occasioned or almost constant, and either about the eyes, forehead, top or back of the head, and often takes the form of "sick headache." The headache may at times appear to have no connection with use of the eyes. When headache is frequent the eyes should always be examined by a competent oculist (a physician) not by any sort of an optician. =Decayed Teeth.=--These not uncommonly give rise to headache. =Disorders of the Nose and Throat.=--Such troubles, especially adenoids and enlarged tonsils in children, enlarged turbinates, and polypi (see Nose Disorders, p. 60) are fruitful sources of headache. In nose-headaches there is often tenderness on pressing on the inner wall of the bony socket inclosing the eyeball.