HEART 492 HEAT son of George Hearst, former United States Senator. He graduated from Harvard in 1885, and taking up his father's interests in San Francisco, be- gan to develop the "San Francisco Ex- aminer." Gradually he established news- papers in other American cities, until he became one of the most povi^erful news- paper owners in the country. He was the owner of the "Los Angeles Exam- iner," the "Chicago Examiner," the "Chicago American," the "Atlanta Geor- gian," the "Boston American," the "Bos- ton Advertiser," the "New York Eve- ning Journal," the "New York Amer- ican" and a number of daily papers in smaller communities. All are notable for their sensational treatment of the daily news. Mr. Hearst was also the owner of the "Cosmopolitan Magazine," "Hearst's Magazine," "Good Housekeeping," "Har- pers Bazar," the "Motor Magazine" and the "Motor Boating Magazine." He was elected to the 58th and 59th United States Congresses (1903-1907), from the Eleventh New York Congressional Dis- trict. In 1905 he was the candidate of the Independence League for Mayor of New York, and candidate for Governor of New York in 1906, but was in both cases defeated. HEART, in human anatomy, the cen- tral organ of circulation, inclosed in a membrane, the pericardium, and lying between the two layers of pleura, the mediastinum, with the base directed up- ward and backward to the right shoul- der, and the apex downward and foi- ward between the fifth and sixth ribs, and to the left. The under side is flat- tened and rests on the diaphragm, the upper rounded and convex, formed by the right ventricle and partially by the left; above these are the auricles whose appendages project forward, overlap- ping the root of the pulmonary artery, the large anterior vessel at the root of the heart, crossing obliquely the com- mencement of the aorta. The right is the venous side of the heart, the left arte- rial. The right auricle is larger than the left, and more complex in structure; it has tvvo valves, the eustachian and the coronary. There is not the same pyra- midal form in the left ventricle as in the right; the apex of the heart is also the apex of the left ventricle, and there- fore larger than the right. The valves of the right ventricle are the tricuspid and semilunar; of the left the mitral (bi- cuspid) and semilunar. The auriculo- ventricular opening connects the auricles and ventricles, and in connection with the ventricular valves we have the columnse cornese, of which there are three sets, and the chordae tendinex. There are three layers of fibers in the ventricles — the external, middle, and internal — their peculiar spiral arrangement causing the tilting forward of the cardiac apex. The fibers of the auricles are in two layers — the external and internal; and the left auricle is thicker and more fleshly than the right. From the right ventricle arises the pulmonary artery, conveying the venous blood to be aerated in the lungs; the infundibulum is a prolonga- tion of the anterior wall. The left auricle contains the four pulmonary veins re- turning the blood to the heart, thence to the left ventricle, and thence to the aorta, to be distributed to every part of the body, returning by the superior and inferior vetw, cava to the right auricle. In the lowest animals we have no blood-vessels, every part absorbing nu- tritious fluid for itself; the lower En- tozoa, and even the embryo in man in its early stage, are examples. Among the higher reptiles, we find the circula- tion approaching that in birds and mam- mals, till we get the double heart, as in man. HEAT, in natural philosophy, the term used chiefly to mean, not the sen- sation which our bodies feel when we say that they are hot, but the particular state or condition of matter which causes this sensation. The accepted hypothesis is that heat is caused by an oscillatory or vibratory motion of the particles of a body. It is thus a condi- tion of matter and not a substance. The hottest bodies are those in which the vibrations move quickest through the widest space. It is called also the Mechanical or Dynamical Theory of Heat. Heat makes bodies, whether solid, liquid, or gaseous, expand, while cold contracts them. Water is a partial ex- ception to the rule. In the case of a solid, heat can produce fusion at a cer- tain definite temperature; in that of liquids vaporization. It is transmitted by radiation or by conduction. Radiant heat is that produced by radiation. Latent heat is that which is absorbed by solid bodies when they are subjected to calorific influence far more than suffi- cient to make them melt, and when at the very time they are in process of fusion. The heat does not raise the temperature of the solid until it is completely lique- fied. There is also a latent heat of vapor- ization, being heat absorbed by liquids when being converted into vapor. Latent is opposed to sensible heat. Heat may be reflected or refracted, or, by being ir-
