receive a small impulse in the time of every descent, its vibrations may be increased to infinity. Did the successive actions of the sun or moon. just keep time with the natural propagation of the tides as the natural oscillations of the waters, the tides would also augment to infinity; but there is an infinite odds against this exact adjustment. It is much more probable that the action of to-day interrupts or checks the oscillation produced by yesterday's action, and that the motion which we perceive in this day's tide is what remains and is compounded with the action of to-day. This being the case, we should expect that the nature of any tide will depend much on the nature of the preceding tide. Therefore we should expect that the superior and inferior tides of the same day will be more nearly equal than the theory determines. The whole course of observation confirms this. In latitude 45°, the superior and inferior tides of one day may differ in the proportion of two and a half to one, and the tides corresponding to the greatest and least declinations of the moon may differ nearly as much. But the difference of superior and inferior tides, as they occur in the list of Observations at Rochefort, is not the third part of this, and the changes made by the moon's declination is not above one-half. Therefore we shall come much nearer the true measure of a spring tide, by taking the arithmetical mean, than by taking either the superior or inferior. We should expect less deviation from the theory in the gradual diminution of the tides from spring tide to neap tide, and in the gradual changes of the medium tide by the declination of the moon; because the successive changes are very small; and when they change in time, that is, diminish after having for some time augmented, the change is by insensible degrees. This is most accurately confirmed by observation. The vast collection made by Cassini of the observations at Brest being examined by Bernoulli, and the medium of the two tides in one day being taken for the tide of that day, he found a considerable agreement between them. He found no less agreement in the changes of the medium tides by the moon's declination. In like manner, the changes produced by the different distances of the moon from the earth, were found abundantly conformable to the theory, although not so exact as the other. This difference or inferiority is easily accounted for: When the moon changes in her mean distance, one of the neap tides is uncommonly small, and therefore the successive diminutions are very great, and one tide sensibly affects another. The same circumstance operates when she changes in apogee, by reason of a very large spring tide. And the changes corresponding both to the sun's distance from the earth and his declination agreed almost exactly. All these things considered together, we have abundant reason to conclude that not only the theory itself is just in principle (which no intelligent naturalist can doubt), but also that the data which are assumed in the appellation are properly chosen; that is, that the proportion of two to five is very nearly the true proportion of the mean solar and lunar forces. If we now compute the medium tide for any place in succession, from spring tide

to neap tide, and, still more, if we compute the series of times of their occurrence, we shall find as great an agreement as can be desired. Not but that there are many irregularities; but these are evidently so anomalous that we can ascribe them to nothing but circumstances which are purely local. We have been considering the tides of an ocean completely to cover the earth. How may those be determined which happen in a small and confined sea, such as the Caspian or the Black Sea? The determination in this case is very simple. As no supply of water is supposed to come into the basin, it is susceptible of a tide only by sinking at one end and rising at the other. It is evident that there will be high water, or the greatest possible rise, when the bason comes to that position where the tangent is most of all inclined to the diameter, and therefore three lunar hours after the moon's southing; at the same time it will be low water at the other end. It is plain that the rise and fall must be exceedingly small, and that there will be no change in the middle. The tides of this kind in the Caspian Sea, in lat. 45°, whose extent in longitude does not excced 8°, are not above seven inches; a quantity so small that a slight breeze of wind is sufficient to check it, and even to produce a rise of the waters in the opposite direction. We have not learnt that tides have been observed in this sea.

The tide should be much greater, though still very small, in the Mediterranean Sea. Accordingly, tides are observed there, but still more remarkably in the Adriatic. We do not know that tides have been observed in the great lakes of North America. These tides, though small, should be very regular. It would be low water on one side of the shore z when it is high water on the other side of this partition. If the tides in the Euxine and Caspian seas, or in the American lakes which are near each other, could be observed, this phenomenon would appear, and would be one of the prettiest examples of universal gravitation that can be conceived. Something like it is to be seen at Gibraltar. It is high water on the east side of the rock about ten o'clock at full and change, and it is high water on the west side, not a mile distant, at twelve. This difference is perhaps the chief cause of the singular current which is observed in the mouth of the Straits. There are three currents observed at the same time, which change their directions every twelve hours. The small tide of the Mediterranean proceeds along the Barbary_shore, which is very uniform all the way from Egypt, with tolerable regularity. But along the north side, where it is greatly obstructed by Italy, the islands, and the east coast of Spain, it sets very irregularly; and the perceptible high water on the Spanish coast differs four hours from that on the south coast. Thus one tide ranges round Europa Point, and another along the shore near Ceuta, and there is a third current in the middle different from both. Its general direction is from the Atlantic Ocean into the Mediterranean Sea, but it sometimes comes out when the ebb tide in the Atlantic is considerable. Suppose the moon over the middle of the Mediterranean. The surface of the sea will be level, and it will be half tides at both ends, and therefore within the

Straits of Gibraltar. But without the Straits it is within half an hour of high water. Therefore there will be a current setting in from the Atlantic. About three hours and a half after, it is high water within, and half ebb without. The current now sets out from the Mediterranean: three hours later, it is low water without the Straits and half ebb within; therefore the current has been setting out all this time: three hours later, it is half flood without the Straits and low water within, and the current is again setting in, &c. Were the earth fluid to the centre, the only sensible motion of the waters would be up and down, like the waves on the open ocean, which are not brushed along by strong gales. But the shallowness of the channel makes a horizontal motion necessary, that water may be supplied to form the accumulation of the tide. When this is formed on a flat shelving coast, the water must flow in and out, on the flat and sands, while it rises and falls. These horizontal motions must be greatly modified by the channel or bed along which they move. When the channel contracts along the line of flowing water, the wave, as it moves up the channe!, and is checked by the narrowing shores, must be reflected back, and keep a top of the waters still flowing in underneath. Thus it may rise higher in these narrow seas than in the open ocean. This may serve to explain a little the great tides which happen on some coasts, such as the coast of Normandy. At St. Malo the flood frequently rises fifty feet. But we cannot give any thing like a full or satisfactory account of these singularities. In the Bay of Fundy, and particularly at Annapolis Royal, the water sometimes rises above 100 feet. This seems quite inexplicable by any force of the sun and moon, which cannot raise the waters of the free ocean more than eight feet. These great floods are unquestionably owing to the proper timing of certain oscillations or currents adjoining, by which they unite, and form one of great force. Such violent motions of water are often seen on a small scale in the motions of brooks and rivers; but we are too little acquainted with hydraulics to explain them with any precision. We have seen that there is an oscillation of waters formed under the sun and moon, and that in consequence of the rotation of the earth, the inertia, and the want of perfect fluidity of the waters, and obstructions in the channel, this accumulation never reaches the place where it would finally settle if the earth did not turn round its axis. The consequence of this must be a general current of the waters from east to west. This may be seen in another way. The moon in her orbit round the earth has her gravity to the earth diminished by the sun's disturbing force, and therefore moves in an orbit less incurvated than she should describe independent of the sun's action. She therefore employs a longer time. If the moon were so near the earth as almost to touch it, the same thing would happen. Therefore, suppose the moon turning round the earth, almost in contact with the equator, with her natural undisturbed periodical time, and that the earth is revolving round its axis in the same time, the moon would remain continually above the same spot of the earth's surface (suppose the

city of Quito), and a spectator in another plane would see the moon always covering the same spot. Now let the sun act. This will not affect the rotation of the earth, because the action on one part is exactly balanced by the action on another. But it will affect the moon. It will move slower round the earth's centre, and at a greater distance. It will be left behind by the city of Quito, which it formerly covered. And as the earth moves round from west to east, the moon, moving more slowly, will have a motion to the west with respect to Quito. In like manner, every particle of water has its gravity diminished, and its diurnal motion retarded; and hence arises a general motion or current from east to west. This is very distinctly perceived in the Atlantic and Pacific oceans. It comes round the Cape of Good Hope, ranges along the coast of Africa, and then sets directly over to America, where it meets a similar stream which comes in by the north of Europe. Meeting the shores of America, it is deflected both to the south along the coast of Brasil, and to the north along the North American shores, where it forms what is called the Gulf Stream (see AMERICA), because it comes from the Gulf of Mexico. This motion is indeed very slow, this being sufficient for the accumulation of seven or eight feet on the deep ocean; but it is not altogether insensible. We may expect differences in the appearances on the west shores of Europe and Africa, and on the west coast of America, from the appearances on the east coasts of America and of Asia; for the general current obstructs the waters from the western shores, and sends them to the eastern shores. Also when we compare the wide opening of the northern extremity of the Atlantic Ocean with the narrow opening between Kamtschatka and America, we should expect differences between the appearances on the western coasts of Europe and America. The observations made during the circumnavigations of captain Cook and others show a remarkable difference. All along the western coast of North America the inferior tide is very trifling, and often is not perceived. In the very same manner, the disturbing forces of the sun and moon form a tide in the fluid air which surrounds this globe, consisting of an elevation and depression, which move gradually from east to west. Neither does this tide ever attain that position with respect to the disturbing planets which it would do were the earth at rest on its axis. Hence arises a motion of the whole air from east to west, and this is the principal cause of the trade winds. They are a little accelerated by being heated, and therefore expanding. They expand more to the west than to the east, because the air expands on that side into air which is now cooling and contracting. These winds very evidently follow the sun's motion, tending more to the south or north as he goes south or north. Were this motion considerably affected by the expansion of heated air, we should find the air rather coming northward and southward from the torrid zone, in consequence of its expansion in that climate. We repeat it, it is almost solely produced by the aerial tide, and is necessary for the very formation of this tide. We cannot per ceive the accumulation. It cannot affect the ba

rometer, as many think, because, though the air becomes deeper, it becomes deeper only because it is made lighter by the gravitation of the sun. Instead of pressing more on the cistern of the barometer, we imagine that it presses less; because, like the ocean, it never attains the height to which it tends. It remains always too low for equilibrium, and therefore it should press with less force on the cistern of a barometer. There is an appearance precisely similar to this in the planet Jupiter. He is surrounded by an atmosphere which is arranged in zones or belts, probably owing to climate differences of the different latitudes, by which each seems to have a different kind of sky. Something like this will appear to a spectator in the moon looking at this earth. The general weather and appearance of the sky is considerably different in the torrid and temperate zones. Jupiter's belts are not of a constant shape and color; but there often appear large spots or tracts of clouds, which retain their shape during several revolutions of Jupiter round his axis. To judge of his rotation by one of these, we should say that he turns round in 9:55. There is also a brighter spot which is frequently seen, occupying one certain situation on the body of Jupiter. This is surely adherent to his body, and is either a bright colored country, or perhaps a tract of clouds hovering over some volcano. This spot turns round in 9:51. And thus there is a general current in his atmosphere from east to west. Both the motion of the air and of the water tend to diminish the rotation of the earth round its axis; for they move slower than the earth, because they are retarded by the luminaries. They must communicate this retardation to the earth, and must take from it a quantity of motion precisely equal to what they want, in order to make up the equilibrated tide. In all probability this retardation is compensated by other causes; for no retardation can be observed. This would have altered the length of the year since the time of Hipparchus, giving it a smaller number of days. We see causes of compensation. The continual washing down of soil from the elevated parts of the earth must produce this effect, by communicating to the valley on which it is brought to rest, the excess of diurnal velocity which it had on the mountain top.

TIDEMAN (Philip), an eminent painter born at Hamburg, in 1657. He studied under Lairesse, and painted subjects of allegory and fabulous history with great propriety. He died in 1705. TIDESWELL, a market-town in High Peak hundred, Derby, five miles east by north from Buxton, and 160 N. N. W. of London. The town is but indifferently built, but the church is large and tolerably well constructed. It has also a free-school. The name of this town is derived from its ebbing and flowing well, reckoned one of the wonders of Derbyshire. Market on Wednesday. Fairs May 3d, October 18th, and first Wednesday in September. TIDI, a river of England, in the county of Cornwall, which joins the Lynker.

TIDINGS, n. s. Sax. dan, to happen; Isl. tidende. News; an account of something that has happened; incidents related.

When her eyes she on the dwarf had set,
And saw the signs that deadly tidings spake,
She fell to ground for sorrowful regret. Spenser.
I shall make my master glad with these tidings.
Shakspeare.

Great numbers of each nation to receive,
They win
With joy, the tidings brought from heaven. Milton.
Portius, thy looks speak somewhat of importance:
What tidings dost thou bring? methinks I see
Unusual gladness sparkling in thy eyes. Addison.
The messenger of these glad tidings, by whom this
covenant of mercy was proposed and ratified, was the
eternal Son of his bosom.
Rogers.

TIDORE, one of the Molucca isles, about twenty-one miles in circumference, is three leagues south of Ternate. The people are principally Mahometans, and there are said to be twenty-five mosques on the island. This island was first visited by the Spaniards under Magellan, November 8th, 1521, who were kindly received, and obtained permission to build a factory. At that period cloves were plentiful here. After visiting the neighbouring islands, Matchian and Batchian, they returned to Europe. In 1527 the Portuguese succeeded in driving them from the island. In 1607 the Dutch arrived in these seas and soon managed to drive out the Portuguese, from which time till its capture by the English it had remained in their hands. The king possesses great part of the south-east portion of Gilolo, in which are three towns of some trade; viz. Patany, Maba, and Weda; he likewise claims the islands of Waygiou, Mysol, and Batanta. There is a great trade here with New Guinea, Gilolo, and with the northern islands; and the Chinese are much interested in it. Long. 127° 25′ E., lat. 0° 45′ N. TIDY, adj. Isl. tidt. ready.

Seasonable; neat;

If weather be faire and tidie, thy grain Make speedilie carriage, for fear of a raine. Tusser. Thou whoreson tidy Bartholomew boar-pig, when wilt thou leave fighting? Shakspeare. Henry IV. Whenever by yon bariey-mow I pass, Before my eyes will trip the tidy lass.

Gay's Pastorals.

TIE, v. a. & n. s. Sax. tian, tigan. To bind; fasten with a knot; knit; hold: hence to constrain; oblige; hinder; obstruct: a knot; fastening; obligation.

Tie the kine to the cart, and bring their calves home from them. 1 Samuel vi. 7. Although they profess they agree with us touching they have declared that it shall not be prescribed as a prescript form of prayer to be used in the church, a thing whereunto they will tie their ministers.

Hooker.

The well-swoln ties an equal homage claim, And either shoulder has its share of fame. Young. TIEDEMANN (Dieteric), a modern German philosopher of eminence, was born April 3d, 1748, at Bremervorde, in Bremen, of which place his father was a burgomaster. He was intended for the study of divinity, but early gave the preference to a more general pursuit of science and literature. In 1772 he published his Essay on the Origin of Languages, (Riga) and in 1776 his System of the Stoic Philosophy. This work, much admired by the celebrated Heyne, procured him the professorships of the Greek and Latin languages in the Collegium Carolinum at Cassel. In 1786 he published his Investigation of Man, 3 vols. 8vo., and in 1780 The First Philosopher of Greece. In 1786 he was removed with the other teachers of the college to Marpurg, and appointed professor of philosophy, in which capacity he sustained a high reputation. His latest performance was a translation of Denon's Travels in Egypt. He died May 24th, 1803, in the fifty-fifth year of his age. Besides the works already enumerated he was also author of a work entitled The Spirit of Speculative Philosophy.

TIER, n.s. Old Fr. tiere, tieire; Ial. tiro; Beig. tuyer. A row; rank.

Fornovius, in his choler, discharged a tier of great ordnance amongst the thickest of them. Knolles.

TIERCE, n. s. Fr. tiers, tiercier. A vessel holding the third part of a pipe.

Go now deny his tierce.

Ben Jonson.

Wit, like tierce claret, when 't begins to pall,
Neglected lies, and 's of no use at all;
But in its full perfection of decay
Turns vinegar, and comes again in play.

Dorset. TIFERNUM, three ancient towns of Italy: 1. called also Metaurense, near the Metaurus, in Umbria 2. called Samniticum, in the country of the Samnites: and 3. called Tiberinum, seated on the Tiber. Liv. x. c. 14. Plin. iii. 14.

TIFERNUS, a mountain and river of Italy, in the country of the ancient Samnites. Liv. x. c. 30. Mela ii. c. 4.

TIGELLIUS, a Sardinian who became a favorite of Julius Cæsar, Anthony, and Cleopatra, by his buffoonery, mimiery, and fine voice; but Horace represents him as a despicable character. 1 Sat. ii. 3, &c.

TIGER, n. s. Fr. tigre; Lat. tigris. A fierce beast of the leonine kind.

When the blast of war blows in your ear,
Then imitate the action of the tiger;
Stiffen the sinews, summon up the blood.

Shakspeare. Henry V. in her skin when she is angry. It is reported of the tigress that several spots rise

Has the steer,

Addison.

Shakspeare.

A tight maid, 'ere he for wine can ask, Guesses his meaning, and unoils the flask.

Dryden's Juvenal. Handle your pruning-knife with dexterity; tightly, I say, go tightly to your business; you have cost me much. Dryden. If the centre holes be not very deep, and the pikes fill them not very tight, the strength of the string will alter the centre holes. Moron's Mechanical Exercises.

O Thomas, I'll make a loving wife;
I'll spin and card, and keep our children tight.

Gay. The girl was a tight clever wench as any. Arbuthnot. I do not like this running knot, it holds too tight; I may be stifled all of a sudden. Id. History of John Bull. The bones are inflexible; which rises from the greatness of the number of corpuscles that compose them, and the firmness aud tightness of their union. Woodward on Fossils.

Every joint was well grooved; and the door did not move on hinges, but up and down like a sash, which kept my closet so tight that very little water came in. Swift.

Drest her again genteel and neat,
And rather tight than great.

Id.