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TIEN-TSIN

1911

TIGER

tide and ebb-tide each last approximately six hours, there being two high and two low tides daily. Each day high water occurs 52 minutes later than the day before, as the average time between two high or low tides is 12 hours and 2 6 minutes Sir Isaac Newton first discovered the cause of the tides by applying his newly discovered law of gravitation, showing that the rising of the waters is due to the difference between the attraction of the moon and of the sun upon the earth as it revolves. As the particles of water are free to move while the particles of land are not, this attraction draws them toward the moon, forming a swell in the ocean's waters. This swell draws toward it waters from both sides, leaving on the coasts a depression, or low water. Gravitation acts on the solid mass of the earth as if this mass were concentrated at the center of the globe. So on the side of the earth opposite that of the moon the waters are less attracted than the land, being at a greater distance, and are as it were, left somewhat behind, thus lorming another swell, just opposite to the one in the other hemisphere. By the rotation of the earth this system of swells and troughs travels from east to west over every part of the ocean. The attraction of the sun also causes two daily tides, but these solar tides are much smaller than the lunar tides. As the moon and sun rarely are in the same relative positions, their high tides do not usually occur at the same time. But at new moon and full moon they are in line with the earth and their attractions act together, causing especially high water, known as the sprtng tides. At the time of the first and of the third quarter of the moon, it is at right angles with the sun, and their attractions act against one another, lessening the height of the high water. These are the neap tides.

A complete explanation of the tides cannot be given in this place. For this the student is advised to read Sir Robert Ball's Time and Tide in the Romance of Science Series; articles 464-84 in Young's General Astronomy; Francis Darwin's Tides, popular lectures before Lowell Institute; and, lastly, his masterly article oil Tides in the Encyclopedia Britannic a.

In the references just given the tides are treated as a wave-motion, which they really are; This is the only point of view from which they can be satisfactorily considered. See WAVE-MOTION.

Tien-Tsin (te-en'tsen), a large city of China, is on Pei-ho River, 38 miles from its mouth and 80 southeast of Pekin. The old mud and dried-brick houses have been replaced, in part by well-built dwellings. The Pei-ho is generally frozen from the middle of December to the middle of March, and business, at other times carried

on by means of boats and junks, is then done by sledges which swarm on the river. Tien-Tsin is an open port; it exports large quantities of cotton, peas and dates and imports cotton-goods, needles, window-glass, sugar and paper. Population 800,000.

Tierra del Fuego (teerfra del fwa'go), "Land of Fire,'* is a cluster of islands at the southern end of South America, with the Straits of Magellan between them and the mainland. They are small, mountainous islands, with many peaks over 5,000 feet high, covered with perpetual snow, while the lower slopes bear forests of beech. The island proper is Tierra del Fuego, 300 miles long. Cape Horn is the southern end of a small island of the group. The natives belong to the Patagonian race; build cone-shaped huts of branches of trees stuck in the ground with a hole for a door; dress in sealskins; and feed largely on shellfish. The climate is very variable, with storms, wind, rain and snow in close succession. The islands were discovered by Magalhaes (Magellan) in 1520, and named from the fires seen at night along the shores. They are nominally divided between the Argentine Republic (q. v.) and Chile (q. v.). See PATAGONIA.

Tiffin, O., county-seat of Seneca County, is 34 miles by rail southwest of Sandusky, on Sandusky River. It is the seat of Heidelberg University, founded in 1850, There also are two daily and four weekly newspapers, a courthouse, three banks, sixteen churches, a convent, several schools and two libraries. It manufactures carriages, stoves, furniture, tiles, farming implements, and has potteries, glass-works, straw-board, emery-wheel and iron works, planing, flour and woolen mills and shoe-factories. Tiffin has the service of four railroads, and near the city are deposits of clay and glass sand. Population 11,894.

Tiflis (tye-ftyes'), an important city of Asiatic Russia on Kur River, 165 miles east of the Black Sea. It is the capital of the Russian government of the same name in Transcaucasia, and is on the military railroad which joins the Black and Caspian Seas. It has a large trade with Persia, and manufactures woolen and linen cloth, carpets and arms. It is noted for its warm-spring baths. Population 159,590.

Ti'ger, the largest and most powerful member of the cat family. The lion appears larger on account of its immense hairy head and mane, but the royal Bengal tigers reach a length of 11 feet and are able to overcome the lion in combat. They have a tawny ground-color, with black stripes on the body and limbs, the tail being ringed with black, the coloring closely resembling that of the herbage. The common tiger is about eight feet in length. It is abundant in Hindustan, does great damage to herds of cattle, and occasionally attacks man.