been demonstrated, by the sagacity of doctor Franklin, that thunder and lightning is merely a case of electrical discharges from one portion of the atmosphere to another, or from one cloud to another. Air, and all gases, are non-conductors; but vapor and clouds, which are composed of it, are conductors. Clouds consist of small hollow bladders of vapor, charged each with the same kind of electricity. It is this electric charge which prevents the vesicles from uniting together, and falling down in the form of rain. Even the vesicular form which the vapor assumes is probably owing to the particles being charged with electricity. The mutual repulsion of the electric particles may be considered as sufficient (since they are prevented from leaving the vesicle by the action of the surrounding air, and of the surrounding vesicles) to give the vapor the vesicular form. In what way these clouds come to be charged with electricity, it is not easy to say. But, as electricity is evolved during the act of evaporation,* the probability is, that clouds are always charged with electricity, and that they owe their existence, or at least their form, to that fluid. It is very probable that when two currents of dry air are moving different ways, the friction of the two surfaces may evolve electricity. Should these currents be of different temperatures, a portion of the vapor which they always contain will be deposited; the electricity evolved will be taken up by that vapor, and will cause it to assume the vesicular state constituting a cloud. Thus we can see, in general, how clouds come to be formed, and how they contain electricity. This electricity may be either vitreous or resinous, according to circumstances. And it is conceivable, that by long continued opposite currents of air, the charge accumulated in a cloud may be considerable. Now, when two clouds, charged, the one with vitreous and the other with resinous electricity, happen to approach within a certain distance, the

* M. Pouillet has lately published a set of experiments which seem to overturn Volta's theory of the evolution of electricity by evaporation. He has shown that no electricity is evolved by evaporation, unless some chemical combination takes place at the same time. But it follows from his experiments, that electricity is evolved abundantly during combustion; the burning body giving out resinous, and the oxygen vitreous electricity. In like manner, the cabronic acid emitted by vegetables is charged with resinous electricity, and the oxygen probably charged with vit reous electricity. These two sources are sufficiently abundant to account for the vast quantity of electricity so often accumulated in the clouds.

thickness of the coating of electricity increases on the two sides of the clouds which are nearest each other. This accumulation of thickness soon becomes so great as to overcome the pressure of the atmosphere, and a discharge takes place, which occasions the flash of lightning. The noise accompanying the discharge constitutes the thunder-clap, the long continuance of which partly depends on the reverberations from neighboring objects. It is, therefore, loudest and largest, and most tremendous, in hilly countries. These electrical discharges obviously dissipate the electricity; the cloud condenses into water, and occasions the sudden and heavy rain which always terminates a thunder-storm The previous motions of the clouds, which act like electrometers, indicate the electrical state of different parts of the atmosphere. Thunder, then, only takes place when the different strata of air are in different electrical states. The clouds interposed between these strata are also electrical, and owe their vesicular nature to that electricity. They are also conductors. Hence they interpose themselves between strata in different states, and arrange themselves in such a manner as to occasion the mutual discharge of the strata in opposite states. The equilibrium is restored; the clouds, deprived of their electricity, collapse into rain; and the thunder terminates. In thunderstorms, the discharges usually take place between two strata of air, very seldom between the air and the earth. But that they are sometimes also between clouds and the earth cannot be doubted. These discharges sometimes take place without any noise. In that case, the flashes are very bright; but they are single flashes, passing visibly from one cloud to another, and confined usually to a single quarter of the heavens. When they are accompanied by the noise which we call thunder, a number of simultaneous flashes of different colors, and constituting an interrupted zigzag line, may generally be observed stretching to an extent of several miles. These seem to be occasioned by a number of successive, or almost simultaneous discharges from one cloud to another, these intermediate clouds serving as intermediate conductors, or stepping-stones, for the electrical fluid. It is these simultaneous discharges which occasion the rattling noise which we call thunder. Though they are all made at the same time, yet, as their distances are different, they only reach our ear in succession, and thus occasion the lengthened

rumbling noise, so different from the snap which accompanies the discharge of a Leyden jar. If the electricity were confined to the clouds, a single discharge, or a single flash of lightning, would restore the equilibrium. The cloud would collapse, and discharge itself in rain, and the serenity of the heavens would be restored; but this is seldom the case. I have witnessed the most vivid discharges of lightning from one cloud to another, which enlightened the whole horizon, continue for several hours, and amounting to a very considerable number, not fewer certainly than fifty, and terminating at last in a violent thunder-storm. We see that these discharges, though the quantity of electricity must have been immense, did not restore the equilibrium. It is obvious from this, that not only the clouds, but the strata of air themselves, must have been strongly charged with electricity. The clouds, being conductors, served the purpose of discharging the electricity with which they were loaded, when they came within the striking distance. But the electric stratum of air, with which the cloud was in contact, being a non-conductor, would not lose its electricity by the discharge of the cloud. It would immediately supply the cloud, with which it was in contact, with a new charge. And this repeated charging and discharging process would continue to go on till the different strata of excited air were brought to their natural state. From the atmospherical electric journal, kept by Mr. Reed, at Knightsbridge, during two whole years, from May 9, 1789, to May 9, 1791, it appears that clouds, and rain, and hail, and snow, are always charged with electricity; sometimes with negative, but more frequently with positive electricity. When the sky is serene and cloudless, the strata of air are generally charged with positive electricity. In such cases, the thunder rod is charged by induction; the highest end acquiring the opposite state of electricity from the air, and the lowest end the same kind of electricity, while a portion of the rod towards the middle is neutral. During the first year, there occurred only seven days in which no electricity could be perceived; and during the second year, when the apparatus was much more complete, not a single day occurred which did not give indications of electricity in the atmosphere. During the first year, the electricity was vitreous or positive 241 times, and, during the second year, 423 times. This difference was chiefly owing to the apparatus. During the first year, there occurred seventy-three days

in which the signs of electricity were so weak that the kind could not be determined. In the second year, it was found that on days when the electricity is weak, it is always vitreous or positive. During the first year, the electricity was observed resinous or negative 156 times, and, during the second year, 157 times. During the first year, sparks could be drawn from the apparatus during ninety-eight days, and, in the second year, during one hundred and six days. From these facts, the probability is, that the electrical state of the atmosphere did not differ much during each of the two years, during which the observations were kept. It would tend greatly to promote the progress of meteorology, which is obviously very much connected with electricity, if a register were kept in the torrid zone of the state of the electricity of the atmosphere during a whole year. The weather in these countries is so regular, and the transition from dry weather to rain so marked, that we have reason to expect corresponding changes in the state of the electricity of the atmosphere. The heaviness of the rain, and the large size of the drops in these countries, indicate that the clouds from which the rain comes are situated at a great height above the surface of the earth. If the accumulation of electricity should be at a corresponding height, this would render a greater height necessary for the rod, by means of which the electrical indications are determined.

THUNDERBOLT; a shaft of lightning; a brilliant stream of the electric fluid passing from one part of the heavens, and particularly from the clouds to the earth. (See the preceding article.)

THUNDERING LEGION. (See Legio Fulminatrix.)

THURGAU, OF THURGOVIA; a canton of Switzerland, bounded north and north-east by lake Constance, south-east and south by St. Gall, and south-west by Zurich and Schaffhausen. The chief town is Frauenfeld. It is divided into eight districts, and has a democratic constitution. The rivers are the Thur and Sitter. It is partly level, and partly hilly; but the elevations do not exceed 2500 feet above lake Constance. It is fertile and well cultivated, producing wheat, barley, oats, rye, flax, hemp, and vines, and has also good pasture. Cotton and silk are manufactured, but the staple article is linen. (See Switzerland.)

THURINGIA (in German, Thüringen); the former name of an extensive tract, in the central part of Germany, in Saxony, having Franconia on the west, and Meis

sen on the east. In the latter part of the fifth century, it was inhabited by the Thuringians, who are then first mentioned in history, and whom some consider as a Visigothic tribe, while others maintain that they are the same as the Hermunduri. The kingdom of Thuringia was conquered by the Frankish kings, in 530, who governed it by dukes. In the thirteenth century, it was annexed to Meissen, or Misnia. It was styled a landgraviate, and gave the title of landgrave to the elector of Saxony; but it was subdivided among many petty princes. The circle of Thuringia comprised the northern part. The name of Thuringia became gradually disused after the incorporation of the territory with other states. It is still, however, preserved, in a limited sense, in the Thuringian forest. The greatest part of the old Thuringia now belongs to Prussia.-See Hersog's Geschichte des Thüringischen Volkes (Hamburg, 1827), or Galletti's Geschichte Thuringens (1781-1785, 6 vols.).

THURINGIA, FOREST OF; a hilly and woody tract, in the interior of Germany, comprising a part of the ancient Hercynian forest, and included within the territories of Prussia, Gotha, Weimar, Meiningen, Hildburghausen, and Coburg. It is about seventy miles long, and from eight to sixteen broad; population, about 188,000; square miles, about 1200. It is covered with wood; thinly peopled, containing only smail villages; but rich in mines, particularly of iron. The highest summit, Schneekopf (q. v.), is about 3000 feet high. Inselsberg, another summit, is nearly as high.

THURLOW, Edward, baron Thurlow, lord high chancellor of Great Britain, was the son of the rector of Ashfield, in Suffolk, where he was born in 1732. He was educated at Caius college, Cambridge; and after having been a student of the Middle Temple, he was, in 1758, called to the bar. He rose to eminence through the display of his abilities in the famous Douglas cause; and he soon after obtained a silk gown. In 1770, he was appointed solicitor-general, in the room of Dunning (lord Ashburton), and the following year he succeeded lord Walsingham as attorney-general. He was now chosen member of parliament for the borough of Tamworth, and became a warm and powerful supporter of the ministry in the house of commons. He retired from office in 1783, but resumed it again on the dissolution of the coalition ministry, and continued to hold the seals

under the premiership of Mr. Pitt till 1792. His death took place in September, 1806. He was succeeded in the peerage by his nephew. He was never married, but left three illegitimate daughters.

THURN AND TAXIS (De la Tour, or Della Torre); a family of princes and counts in Germany, which originated in Milan. The first of this family, it is said, received the name Della Torre from St. Ambrose, bishop of Milan (from 374 to 397), on account of his defence of the new gate against the Arian rebels. In 1313, Lamurald de la Tour took the surname of Taszis, now Taxis. His great grandson Roger I, count of Thurn and Taxis and Valsassina, went to Germany, where he established the first posts (q. v.) in Tyrol. The post establishment in the German empire became, at a subsequent period, a fief of the family, which, in Germany, as well as in several other countries, enjoyed great privileges, so that they became rich and powerful. Many important privileges have been continued to this family since the new organization of the German confederacy. The present head of the family has an income of about 800,000 guilders a year, and possesses about 260 square miles, in various German countries, with 30,746 inhabitants. Besides the princely line, there are four lines of counts.

THURSDAY (in Latin, dies Jovis, whence the French Jeudi); the fifth day of the week, so called from the old Teutonic god of thunder, Thor, the northern Jupiter. (See Thor.) The German name for Thursday is Donnerstag (Thunderday), thunder being the chief attribute of Thor. (See Maunday-Thursday.) Ascension day (q. v.) is also called Holy Thursday.

THUSNELDA; wife of Arminius. (q. v.) THYADES; the same as Manades. (q. v.) THYESTES; Son of Pelops and Hippodamia. Having seduced the wife of his brother Atreus (q. v.), the latter, in revenge, served up to him the body of his own son at a feast. Thyestes, discovering the fact, fled to Sicyon with his daughter Pelopia, by whom he had a son, Ægisthus. An oracle had declared that the son and grandson of Thyestes should revenge the crime of Atreus; and when Ægisthus was grown up, he accordingly murdered his uncle, at the instigation of his father. Thyestes then ascended the vacant throne, but was afterwards expelled by Agamemnon and Menelaus, the sons of Atreus, and died in banishment on the island of Cythera. The tragedies of Sophocles

and Euripides, on this subject, are lost; that of Seneca is yet extant.

THYME (thymus vulgaris); a small labiate plant, a native of the south of Europe, and frequently cultivated in gardens. The stems are branching, eight inches or a foot in height; the leaves simple and opposite; and the flowers disposed in whorls near the summits of the branches. All parts of the plant have a strong and penetrating odor, as is usual in this family. Its essential oil is extremely acrid and pungent, and is used for culinary purposes, but less so now than before the Oriental spices were common. Bees are very fond of this, as well as of other labiate plants, and the honey obtained is of superior quality. The thyme of mount Hymettus is celebrated. We have no native species of thyme in America, but T serpyllum is naturalized in many parts of the U. States. This plant has the same sensible qualities as the garden thyme, but the flavor is milder and rather more grateful, and the essential oil less abundant and not so powerful.

THYRSUS (Greek Ovpros); one of the most ancient and common attributes of Bacchus and his followers. It consisted of a lance, the iron part of which was hidden in a cone of pine, in memory of the stratagem which the followers of Bacchus employed against the Indians, when they went to combat them with pikes, the iron of which was concealed by ivy leaves. It was used at all the festivals held in honor of the god of wine, and often enveloped with wreaths of ivy or bay, or with little fillets of other kinds. (See Bacchus.)

TIARA; originally, and with Herodotus, the cap of the Persian kings. The tiara of the pope is a high cap, surrounded by three crowns rising one above the other. These crowns are covered with precious stones, and ornamented with an orb, on which stands a cross, and on two sides of it a chain of precious stones. Originally, the popes wore a common bishop's mitre. (See Infula.) It has been said, but not proved, that Clovis, the Frankish king, in the fifth century, or Constantine the Great, in the beginning of the third century, presented the pope with a gold crown, which the latter united with the infula. According to Henke (Ecclesiastical History, in German, vol. ii.), the popes first wore the simple crown in the ninth century; Cicognara (Storia della Scultura, &c.), however, is of opinion, that only Alexander III, in the twelfth century, surrounded the mitre with a crown, as a

sign of sovereignty. Boniface VIII (who died in 1303) is said to have added the second, as a sign of power over spiritual and temporal things, and Urban V (who died in 1370) the third, in order, as is believed, to indicate the power of the pope in the church, suffering, militant and triumphant (or in heaven, on earth and in hell.) Perhaps the three crowns were to indicate the three parts of the globe at that time known. At the consecration or coronation of the pope, the following words are pronounced: Accipe tiaram tribus coronis ornatam, et scias te esse patrem, principem ac regem, rectorem orbis in terra, vicarium Salvatoris nostri Jesu Christi. As the mitre is placed over the coat of arms of bishops, and the cardinal's hat over that of the cardinals, so the tiara, with the two keys, is placed over the family coat of arms of the pope. On coins, &c., the tiara and two keys are often found alone.

sea.

TIBER; a river in Italy, which rises in the Apennine mountains, and, in its course of about 160 miles, receives several small rivers, as the Teverone, the Chiana, Puglia, Nera, &c., runs through Rome, and empties, at Ostia, into the Tuscan It owes its fame to the Roman poets. In itself it is insignificant, and always muddy. The fishes in it are not healthy, and are bad tasted. It is navigable only for small craft. Its water is yellow and thick. It has been long believed that this river contains many antiquities-an opinion founded on its frequent inundations in former times; nay, it has been even said, that Gregory the Great, in his religious zeal, ordered the statues and monuments of heathen antiquity to be thrown into the Tiber. Fea, in his work Novelle del Tevere (Rome, 1819), maintains, on the contrary, that little would be gained by exploring the mud of the river; and the most recent undertaking of this kind (see Excavations) confirms his opinion. That part of Rome which is situated to the west of the Tiber, or on its left bank, is called Trastevere, and contains the Vatican, with several other important buildings. The inhabitants of this quarter are distinguished by many peculiarities from the other Romans, and are called Trasteverini. (See Rome.)—An insignificant creek in Washington has been dignified with the name of Tiber.

TIBERIAS. (See Genesareth.)

TIBERIUS, Claudius Nero, a Roman emperor, born B. C. 42, was the son of a father of the same name, of the ancient Claudian family, and of Livia Drusilla,

the wife of Augustus. Rapidly raised to authority by the influence of his mother, he displayed much ability in an expedition against some revolted Alpine tribes, in consequence of which, he was raised to the consulate in his twenty-eighth year. On the death of Agrippa, the gravity and austerity of Tiberius having gained the emperor's confidence, he chose him to supply the place of that niinister, obliging him, at the same time, to divorce Vipsania, and wed his daughter Julia (q. v.), whose flagitious conduct at length so disgusted him, that he retired, in a private capacity, to the isle of Rhodes. After experiencing much discountenance from Augustus, the deaths of the two Cæsars, Caius and Lucius, induced the emperor to take him again into favor and adopt him. (See Augustus.) During the remainder of the life of Augustus, he behaved with great prudence and ability, concluding a war with the Germans in such a manner as to merit a triumph. After the defeat of Varus and his legions, he was also sent to check the progress of the victorious Germans, and acted in that war with equal spirit and prudence. On the death of Augustus, he succeeded (A. D. 14), without opposition, to the sovereignty of the empire, which, however, with his characteristic dissimulation, he affected to decline, until repeatedly solicited by the servile senate. The new reign was disquieted by dangerous mutinies in the armies posted in Pannonia and on the Rhine, which were, however, suppressed by the exertions of the two princes, Germanicus and Drusus. The conduct of Tiberius, as a ruler, has formed a complete riddle for the student of history, uniting with an extreme jealousy of his own power the highest degree of affected respect for the privileges of the senate, and for the leading virtues of the ancient republican character. He also displayed great zeal for the due administration of justice, and was careful that, even in the provinces, the people should not be oppressed with imposts a virtue which, according to Tacitus, he retained when he renounced every other. Tacitus records the events of this reign, including the suspicious death of Germanicus (q. v.), the detestable administration of Sejanus (q. v.), the poisoning of Drusus (q. v.), with all the extraordinary mixture of tyranny with occasional wisdom and good sense, which distinguished the conduct of Tiberius, until his infamous and dissolute retirement (A. D. 26) to the isle of Capreæ, in the bay of Naples, never to return to

Rome. On the death of Livia, in the year 29, the only restraint upon his actions, and those of the detestable Sejanus, was removed, and the destruction of the widow and family of Germanicus followed. (See Agrippina.) At length, the infamous favorite extending his views to the empire itself, Tiberius, informed of his machinations, prepared to encounter him with his favorite weapon, dissimulation. Although fully resolved upon his destruction, he accumulated honors upon him, declared him his partner in the consulate, and, after long playing with his credulity, and that of the senate, who thought him in greater favor than ever, he artfully prepared for his arrest. Sejanus fell deservedly and unpitied; but many innocent persons shared in his destruction, in consequence of the suspicion and cruelty of Tiberius, which now exceeded all limits. The remainder of the reign of this tyrant is little more than a disgusting narrative of servility on the one hand, and of despotic ferocity on the other. That he himself endured as much misery as he inflicted, is evident from the following commencement of one of his letters to the senate: "What I shall write to you, conscript fathers, or what I shall not write, or why I should write at all, may the gods and goddesses plague me more than I feel daily that they are doing, if I can tell." What mental torture, observes Tacitus, in reference to this passage, which could extort such a confession! In the midst, however, of all this tyranny, he often exhibited gleams of strong sense, and of a judicious attention to the public welfare-a remark which holds good in every part of his anomalous reign. Having at length reached an advanced age, Caius Caligula, the son of Germanicus, his grandson by adoption, and Gemellus, the son of Drusus, his grandson by nature, became objects of interest. Caius, however, who had reached the age of twentyfive, and who held the popular favor as a paternal inheritance, was at length declared his successor. Acting the hypocrite to the last, he disguised his increasing debility as much as he was able, even affecting to join in the sports and exercises of the soldiers of his guard. At length, leaving his favorite island, the scene of the most disgusting debaucheries, he stopped at a country house near the promontory of Misenum, where, on the sixteenth of March, 37, he sunk into a lethargy, in which he appeared dead; and Caligula (q. v.) was preparing, with a numerous escort, to take possession of the