class decandria, and order monogynia ; natural order, Tricoccs.Calyx five-parted; petals five; capsule tricoccous, there is onlyone species known, viz T. Brasiliensis, a native of Brazil .
THUANUS, Jacobus Augustus , or James Augustus DeThou, youngest son of the president de Thou , was famous for thedepth and erudition of his works. He was born in 1553; andhav mg finished his studies and travels, was made president a Mor-tier, and took possession thereof in 1595. He was employed inseveral important offices of state, and in reforming the universityof Baris ; which he discharged with so much prudence, that hewas esteemed the Cato of his age, and the ornament of France .He wrote the History of his Own Time, in Latin , from 1543 to1608, in 138 books ; a work, both for subject and style, worthy ofthe ancients. He also left Memoirs of his own Life, besidespoems ; and died at Paris, 1617.
THUCLES, the leader of the first Greek colony who settled inSicily .
TH UCYDIDES, a celebrated Greek historian, born at Athens 471 years B. C. He was the son of Olorus, and grandson ofMiltiades, who was descended from Miltiadesthe famous Athenian general, who married the king of Thrace ’s daughter. He waseducated in philosophy and eloquence. IT is master in the formerwas Anaxagoras , in the latter Antiphon; one, by his description inthe 8th book of his history, for power of speech almost a miracle,3nd feared by the people on that account. Suidas and Photius mention, that when Herodotus related his history in public, acustom then common, and many ages after, Thucydides felt sucha pang of emulation, that he shed tears; Herodotus himselfnoticed it, and congratulated his father on having a son who shewedso early an affection to the Muses. Herodotus was then 29 yearsof age, Thucsdides about 16. When the Peloponnesian warbroke out, Thucydides , thinking it would prove a subject worthy°f his labour, immediately began to keep a journal. This ex-plains the reason why he has attended more to chronological orderthan to unity of design. During the war he was sent bv hiscountrymen to relieve Amphipolis; but the quick march of Bra -sidas the Lacedaemonian general defeated his operations ; andThucydides being thus unsuccessful, was banished from Athens , inthe 8th year of this celebrated war, but during his banishment thegeneral began to write an impartial history of the important eventsWhich had happened during his administration, and which stillcontinued to agitate the states of Greece . This famous history iscontinued only to the 21st year of the war, and the remaining partof the time till the demolition of the walls of Athens was describedby Theopompus and Xenophon. Thucydides wrote in the Atticdialect, which has most vigour, purity, elegance, and energy.Thucydides died at Athens , where he had been recalled fromhis exile about 411 years B. C. The best editions of his works®re those of Oxford! in folio, 1696, and of Duker, Amsterdam ,h73i, also fol.
THUJA, the Arbor ViriE, or Tree of Life ; in botany, a8 e »us of plants of the class monadelphia, and order moncccia;Natural order, Conifera 1 . Male, calyx scale of an ament; corollaNone; stamina four: female, calyx of a strobile, with a two-fiow-Jjfed scale ; corolla none; pistil one; nut one, girt with a mem-branaceous wing. There are four species.
. P. Orientalis, the Chinese Arbor Vitje, grows naturallyjn the N. parts of China , where it rises to a considerable height.The branches grow closer together, and are much better adornedleaves, which are of a brighter green colour, so make a muchbe Uer appearance than the last species, and being very hardy, it isN'oeined preferable to most of the evergreen trees with'small leaves,;° r ornament in Gardens. These trees are propagated by seeds,
^ a j£ rs . or cuttings.
THUlN, a town of the Netherlands , in the bishopric of Liege,
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th
* p -ated oil the Sambre, 8 miles S. W. of Charleroy, 15 S. E. ' offT°us, and 48 VY. S. W. of Liege. Lon. 4. 22. E. Lat.h°. 21. N
Thule, or TIlYLiE, in ancient geography, an island ine most northern part of the German Ocean. Its situation wasever accurately ascertained by the ancients, hence its presenta >'ie is unknown by modern historians. Some suppose that it is, e island now called Iceland, or part of Greenland , and othersll *at nwasFoula.
J hule, Southern, a part of Sandwich Lund, in the Southtv— so. 207.
Atlantic Ocean . See Sandwich. Lon. 27. 45. W. Lat. 59.34. S.
THUMB, in anatomy, is the extremity of the hand. SeeAn atomy.
THHMERSTONE, ill mineralogy, a species of the flint ge-nus : common colour is brown of various degrees of intensity : itis seldom found massive, often disseminated, but most frequentlycrystallized. Specific gravity about 3.3. It inelis easily beforethe blow-pipe, without addition, into a greenish, white, semi-trans-parent glass. The constituent parts are,
100.00
It appears to be peculiar to the primitive mountains, and is fouiidin Cornwall, and in several parts of the continent of Europe .
THUMMIM. See Urim.
THUN, a large and handsome town of Switzerland , in thecanton of Berne, 15 miles S. S. E. of Berne . Lon. 7. 17. E. Lat.46.38. N.
THUNBERGIA, in botany, a genus of plants of the class di-dynamia, and order angiospermia. Calyx double; exterior di-phyllous ; interior multipartite ; capsule globose, beaked, bilocu-lar. There are two species.
THUNDER is the noise occasioned by the explosion of a flashof lightning, echoed back from the inequalities on the surface ofthe earth, in like manner as the noise of a cannon is echoed, and inparticular circumstances forms a rolling lengthened sound. It isuniversally allowed, that the variation of the electricity in dif-ferent parts of the atmosphere is the cause of thunder. Under thearticle Electricity, it has been shewn why lightning explodesafter the thunder clouds are charged. In this part of Great Bri-tain , and for a considerable way along the E. coast, althoughthunder may happen at any time of the year, yet July is that inwhich it may almost certainly be expected. Its duration is ofvery uncertain continuance ; sometimes only a few peals will beheard at any particular place during the whole season ; at othertimes the storm will return at the interval of three or four days forfive or six weeks, or longer; not that we have violent thunder inthis country directly vertical in any one place so frequently in anyyear, but in many seasons it will be perceptible that thunder-clouds are formed in the neighbourhood even at these short inter-vals. Hence it appears, that during this particular period theremust be some natural cause operating for the production of thisphenomenon, which does not take place at other times. Thiscannot be the mere heat of the weather, for we have often a longtime of hot weather without any thunder ; and besides, though notcommon, thunder is sometimes heard in winter. As therefore theheat of the weather is common to the whole summer, whether therebe thunder or not, we must look for the causes 6f it in those phne-nomena which are peculiar to July, August, and September.Now it is generally observed, in the above mentioned tract ofcountry; that from April an E. or S. E. wind generally takesplace, and continues with little interruption till towards the end ofJune. At that time, sometimes sooner and sometimes later, a W.w ind takes place ; but as the causes producing the E. wind are notremoved, the latter opposes the VV. wind with its whole force.At the place of meeting, there is naturally a most vehement pres-sure of the atmosphere, and friction of its parts against one ano-ther ; a calm ensues, and the vapours brought by both winds be-gin to collect and form dark clouds, which can have little motioneither wav, because they are pressed almost equally on all sides.For the most part, however, the VV. wind prevails, and what littlemotion the clouds have is towards the E. whence the commonremark in this country, that 11 thunder-clouds move against thewind.” But this is by no means universally true: for if the W.wind happens to be excited by any temporary cause before itsnatural period when it should take place, the E. wind will oftenget the better of it; and the clouds, even although thunder is pro-9 B duced,