TICONDEROGA. 274 TIDES. were then enlarged and strengthened by the Eng- lish. Being T;eakly garrisoned after the cession of Canada to Great Britain, Ticonderoga was surprised and captured on May 10, 1775, by Ethan Allen. On June 30, 1777, Burgoyne in- vested it, and on July 5, by placing a battery on Mount Defiance, a higher point, then called Sugar Loaf Hill, he forced the garrison to evacuate tlie place. Later in the year General Lincoln attacked the British here and cap- tured Mount Defiance, releasing 100 Ameri- can prisoners and taking 293 of the English, but he failed to recover the fort itself. After Burgoyne surrendered at Sara- toga, the English garrison was removed and the fort dismantled, though in 1780 another English force under General Haldimand was stationed here for a time. After the war the fort gradually fell in ruins. TIC-POLONGA. See Daboia and Colored Plate under Snake. TICUNA, te-kuU'na, or Tucuna. A wild tribe of uncertain afiinity inhabiting the forests of the Upper Amazon (Maranon) about the con- fluence of the Javary, on the Brazil-Peru fron- tier. They go perfectly naked, excepting for neck- laces of monkey teeth and armlets of feathers, and depend for a living upon hunting and fishing. Physically they are well formed, and rather slender, with a dark complexion and a gentle expression. In disposition they are honest and direct. They bury their dead in great earthen jars, with their face turned toward the rising sun, and weapons and fruit placed upon the bosom. The.v have interesting masked dances and curious ceremonies at the naming of children. Jesuit missions were established between 1683 and 1727. TIDAL WAVE. A term erroneously applied to almost any unexpected wave that inundates the seacoast or the shore of a great lake. These waves are rarely, if ever, due to the tides, since the tidal wave is a phenomenon admitting of exact calculation and prediction: on the other hand, they may usually be ti'aced to some distant earthquake or violent storm. See Earthquake. TIDEMAND, te'da-man. Adolf (1814-76). A Norwegian genre painter, born at Mandal. He studied at the Academy of Copenhagen and under Theodor Hildebrandt and Schadow at Diisseldorf, whence he went to Munich and later to Rome. Afterwards he usually spent the summer in Nor- way and the winter at Diisseldorf, where Scan- dinavian artists congregated around him and Gude. Besides the large historical compositions "Gustavus Vasa Addressing the Dalecarlians" (1841) and "Devotional Meeting of the Hau- gainer" (gold medal. 1848, National Gallery, Christiania, and Diisseldorf Gallery), he painted many genre subjects, remarkable for masterly conception and vigorous coloring, such as the cvcle of ten pictures illustrating "Norwegian Peasant Life" (1850, Chriteau of Oscarshall. near Christiania ) ; "Summer Evening on a Lake" (1851, National Gallery. Berlin): "The Wolf- Hunter's Tale" (18531 'and "A Funeral in Nor- way" (1854, both in the Ravene Gallery, ib.) ; "Grandmother's Bridal Crown" ( 1865, Karlsruhe Gallery), and others. He died at Christiania. TIDES (AS. Ud, OHG. zit, Ger. Zeit, time; connected with Skt. a-diti, boundless, and ulti- mately with Eng. time). The daily rising and falling of the waters of the ocean. When the. water has reached the highest point it is called liii/li, icater, and at its lowest point low water. The rising of the water is called jlood, the falling f66. Tides are caused by the gravitational at- traction or pull of the sun and moon upon the water, and upon the earth itself. The moon, being so much nearer than the sun, is of course the principal cause. When the moon is directly over a given place it pulls the water under it, and thus tends to heap up a tidal wave just under the moon. At the same time it is pulling the earth itself ; but it pulls the water more than the earth underneath, simply because the moon is nearer to the water on the surface than it is to the solid earth behind it. For we must remem- ber that, according to Newton's law of attraction, the pull decreases rapidly when the body pulled is removed to a greater distance. But this reason also makes the attraction exerted upon the solid earth greater than that affecting the mass of water U])on the side of the earth opposite to the moon. This water, being still fartlier awaj' than is the solid earth, gets the least pull of all. The earth is, so to speak, pulled away from that part of the ocean that is opposite the moon, instead of directly under it. This causes another distinct heaping up of water opposite the moon, giving us a second tidal wave. There should be, therefore, two lunar tidal-wave crests, one directly under the moon and tire other on the side of the earth opposite the moon. Tliis explanation is modified somewhat on account of the attraction of the sun, which at times tends to increase, and again at times to diminish, the lunar tide. We thus get the high tides of new and full moon (spring tides) and the low tides of certain other ages of the moon (neap tides). And the double tidal wave explains why there are two high tides and two low tides every twenty-four hours. This ex- planation is called the ■equilibrium' theory of the tides. It is ver,v plausible, but unfortunately it fails to agree with observed facts, though it is nevertheless of great use in leading up to a better theory. Under the equilibrium theory we should expect high water at any place about the time when the moon, as astronomers say, passes the meridian. This time might be modified by the solar effects, but only to a rather small amount easily calculated. Unfortunately, this is not in accord with observation. There are places where the high water conies as much as six hours away from the meridian passage of the moon. In other words, the equilibrium theory is at times in error by the maximum possible amoimt. The trouble is that it tells us what would happen if the forces governing the tides had plenty of time to act. But the turning of the earth on its axis continually presents a new meridian to the moon, so that the tidal-wave crest is always following the moon, ever trying to be highest directly under it. Thus what should occur under the equilibrium theory is greatly modified by the theory of the motion of fluid waves. This leads them to the 'dynamical' theory of the tides. A consideration of the subject is much simpli- fied by assuming a condition of things that does not really exist in nature. Let us imagine a canal full of water encircling the earth at the equator. Sir Isaac Newton was the first to in- vestigate what would happen to a wave set itt
