720 THOMSON the First Principles of Chemistry by Experi- ment" (2 vols., 1825) ; " The History of Chem- istry" (2 vols., 1830-'31); "Outlines of Min- eralogy and Geology" (2 vols., 1836); and "Brewing and Distillation" (1849). His son THOMAS, superintendent of the East India com- pany's botanic gardens at Calcutta, has pub- lished an -account of his travels in the western Himalaya and Thibet (8vo, 1852). THOMSON, William, an English clergyman, born in Whitehaven, Feb. 11, 1819. He was educated at Queen's college, Oxford, of which ho was successively fellow, tutor, and pro- vost. He was ordained in 1842, became select preacher at Oxford in 1846, Bampton lecturer in 1853, rector of All Souls, Marylebone, in 1855, preacher of Lincoln's Inn in 1858, bishop of Gloucester and Bristol in 1861, and arch- bishop of York in 1863. He has published "The Atoning Work of Christ" (London, 1853); "Outline of the Necessary Laws of Thought," a text book in several English and American colleges (1842 ; 9th ed., 1868); "Life in the Light of God's Word " (1867) ; " Limits of Philosophical Inquiry" (1868); and ser- mons, pastoral letters, and lectures. THOU, in Scandinavian mythology, the first born of Odin and Frigga, the bravest and bold- est of all the gods. He directed the winds and the seasons ; agriculture and the family rela- tions were under his special care ; and, unlike Odin, he was opposed to war among men. In the Eddas he appears as the champion of gods and men, destroying monsters and giants with his bolts of thunder. A terrible hammer was hurled at his victim, and after the blow was dealt the weapon returned to his hand. His waist was bound with a girdle which forever renewed the strength he spent in battle. Thor has been compared with Hercules, Jupiter, and the old Saxon deity Irmin. The fifth day of the week has from him received its name, Thursday. THORAX (Gr. d6pat- the chest, or tipper part of the trunk of the body, situated between the neck and the abdomen. The osseous frame- work of the thorax consists of the 12 dorsal vertebrae behind, the sternum or breast bone in front, and the ribs upon each side. The spaces between the ribs are occupied by the intercostal muscles, external and internal. The floor or inferior wall of the thor.ax is consti- tuted by the diaphragm, a vaulted muscular sheet, with a central tendinous expansion, the convexity of which looks upward toward the chest, while its concavity looks downward to- ward the abdomen. The general form of the thorax is conical, with a broad base below, and presenting at its upper extremity a com- paratively narrow and nearly circular open- ing, bounded on each side by the curved bor- ders of the first pair of ribs, through which the trachea, oesophagus, nerves, and blood vessels pass from the neck into the chest, or vice versa. The framework of the chest thus constituted 'has a considerable degree of elasticity, owing THORAX to the curved form of the ribs themselves, and to the fact that they are articulated with the sternum by elastic cartilages of variable length, oblique in position. Owing to the mobility of the ribs at their vertebral articulations, they are capable of being rotated outward and ele- vated by the action of the intercostal muscles, and of thus expanding the cavity of the chest laterally. The expansion also takes place at the same time in an antero-posterior direc- tion, since the sternum itself is elevated by the movement of the ribs and carried further away from the spinal column ; in this way is produced the alternate rising and falling of the walls of the chest during respiration. By the contraction of the diaphragm the central ten- don of this muscle is drawn downward at the moment of inspiration, thus also expanding the chest vertically. The cavity of the thorax has a general conoidal form, corresponding with Cavity of the Thorax in Man, opened anteriorly, showing the internal organs, a, &, c. Upper, middle, and lower lobes of the right lung, d, e. tipper and lower lobes of the left lung. /. Heart, g. Pulmonary artery, h. Pul- monary vein. ^. Aorta, k. Superior vena cava. I. Up- per surface of the diaphragm, m. Lower extremity of the sternum, n. Trachea. its external configuration. It is partially divi- ded, however, into lateral halves by the for- ward projection of the bodies of the dorsal ver- tebrae, leaving on each side of the spinal column a tolerably deep rounded groove or furrow. The principal organs contained in the cavity of the thorax are the heart, lungs, and great blood vessels. The heart is situated nearly in the median line, with its point directed down- ward and toward the left side, and the lower part of its inferior and posterior surface rest- ing upon the central tendon of the diaphragm. The superior and inferior venaa cavaB, the aor- ta, the pulmonary artery, and the pulmonary veins are connected with the base of the heart, mostly about the level of the junction of the third costal cartilage with the sternum. Tho lungs are on each side, moulded to the form of the cavity in which they are contained, and
