T H U
make five metacarpal bones. The convex fide of this phalanx is very much flatted, and is much broader toward the head, than toward the bans. On the concave fide is a kind of an- gular line, which in fome meafure diftinguifhes it into two parts. Its head is like thofe of the metacarpal bones, only flatted at top. The articular fide of its bafis is proportioned to the digital fide of the os trapezium of the carpus, and fram- ed in fuch a manner as that the figmoide cavities and eminen- ces in the two bones crofs one another. This articulation has fomething very particular in it ; it is a kind of double gingly- muSj which readily allows of flexion and extenfion, adduc- tion and abduction, but with difficulty permits the oblique motions, becaufe then the two fides run counter to each other.
The fecond phalanx of the Thumb is Shorter than the firft ; its body is convex or femi cylindrical on one fide, flat on the other, and contracted between the edges. The articular fide of the bafis is gently concave, and is furrounded near the edges by fmall tuberofities ; as alfo near the angle of the pha- lanx. The head is the regular portion of a pulley, which pro- jects more on the concave, than on the convex fide ; and on each fide of it there is a fmall fofTula, and fome inequalities in form of tubercles. On the flat or concave iide of the pha- lanx are two rough lines, one near each edge; they are the impreifions or marks of the articular vaginae. The connec- tion of this phalanx with the firft, is by a kind of arthrodia, or by a flat enarthrofis, which permits a motion in feveral direc- tions, though more limited than in other articulations of the fame kind. It is articulated with the third by a very perfect ginglymus.
The third phalanx of the Thumb reprefents the half of a fort of cone, cut lengthwife, and by joining it to the fame bone of the other Thumb, an entire cone is formed ; the convex fide is more even than the flat fide, and on each edge there is a tuberofity near the bafis : The bafis has two hollow fides, which form a ginglymus with the head of the fecond phalanx. The head is flat and fmall, ending in a rough femi-circular border, which on the flat fide of the bone reprefents a horfe- fhoe. PFinfow's Anat. p. 87. THUNDER (Cycl.)— The noiCe ot Thunder and the flame of lightning are eafily made by art. If a mixture of oil or fpirit of vitriol be made with water, and fome filings of iteel ad- ded to it, there will immediately arife a thick fmoak, or va- pour, out of the mouth of the veflel ; and if a lighted candle be applied to this, it will take fires the flame will imme- diately defcend into the vefiel, and this will be burft to pieces, with a noife like that of a cannon.
This is fo far analogous to Thunder and lightning, that a great cxplofion and fire are occafioned by it ; but in this they differ, that this matter when once fired is destroyed, and can give no more explofions ; whereas in the heavens one clap of Thun- der ufually follows another, and there is a continued fuccef- fion of them for a long time. Mr. Homberg explained this by the lightnefs of the air above us, in comparifon of that here, which therefore would not fuffer all the matter fo kind- led to be diflipated at once, but kept it for feveral returns. Thunder-5/jw, in natural hiftory, the fame with that called
by authors Brontia. See the article Brontia. THUND£R-5/or//ij. It is frequent in the Thunder -ft arms in hot climates, to fee a bituminous matter fall with the lighten- ing to the ground, and there continue for fome time burning in a mafs, or elfe burft at once into a multitude of fparks, which burn every thing they touch, and always leave a violent fmell of brimftone behind them.
Something of this nature, but concreted into a foiid form and refcmbling common brimftone, was fome years ago obferved in the ifle of Wight ; of which Mr. Cook, an inhabitant of Newport there, has given the following account : The month of July, in the year 1737, had been very fultry and the nights often ftormy, in particular there was one even- ing a very violent ftorm of Thunder and lightening, attended toward the end with a great deal of rain. The morning af- terwards, as a countryman was walking over a meadow near the fea-fide, he obferved a yellow ball of a fhining matter, lying loofe upon the turf or grafs. When he had taken it up. he found it to be no other than a lump of fulphur, of an un- commonly ftrong fmell, and covered all over with a multi- tude of fine mining cryltals of a yellowifh colour, which fell off on the lighteft touch. The whole fubftance appeared to he fomewhat fpungy, and it had a large hole in one part ; ir was near an inch long, and fomewhat more than half an inch in diameter, and when put to the fire proved readily in- flammable, and burnt with a whiter flame than common brimftone, and with lefs acid and fuffocating fumes. The author of this account feems to think, that there is great probability that this ball was generated, not under ground but in the air, and that it was of the nature of thofe maffes of bituminous matter falling fo frequently in Thunder-Jiorms, in the hotter countries, but that by fome accident it miffed tak- ing fire, and was therefore left perfect in its folid form. It feems not to have been generated under ground, fince if it hud, it could never have been found on the furface fo per- fectly clean, with its pores all empty not filled with earth, and its covering of cryftals untouched, though they adhered
THY
fo very lightly to it that the gentleft touch threw them off". Phil. Tranf. N°. 450. p. 449. THURIBULUM, among the Romans, a cenfer or vefiel, in
which incenfe was burnt at facrifices. Pitifc. in voc. THURIFICATI, in church hiftory, a designation given to thofe, who, to avoid the perfecution of the Roman emperors, offered franlcinccnfe to the heathen gods. Hofm, Lex. in voc. See the article Persecution. THURSIO, in ichthyology, a fpecies of fifh, mentioned by Pliny, 1. g. c. 9. It is thought by fome to be the Phocana^ or porpoife ; and by others the Sturgeon. Hofm. Lex. univ. in voc. See the articles Porpoise, and Sturgeon. THURUS, in natural hiftory, the name of a creature defcribed by Gefner, and fome others, as a diftinct fpecies of wild bull ; but the accounts of it feem either fabulous, or miftaken defcriptions of the wild bull. See die article Bos. THUYA, Tree of life, in botany the name of a genus of trees, the characters of which are thefe : The embryo fruits are of a fquammofc ftructure, and finally become a fort of oblong fruit, between the fcales of which there lie a fort of margi- nated feed. To this it is to be added, that the leaves are fcaly.
The fpecies of Thuya, are the common arbor vita, and the Chinefe kind. Tourn. Inft. p. 587. THWART the Hazvfe, in the fea language. See the article
Hawse. PHYIA, Qma., in antiquity, a feftival in honour of Bacchus* celebrated by the Eleans. Potter, Archaeol. Gnec. I. 2. c. 20. T. 1. p. 405. THYITES Lapis, in the materia medica of the antients, the name of an indurated clay, approaching to the nature of a ftone. It was found in Egypt, and ufed in diftemperatures of the eyes.
This fubftance has been very much mifunderitood by the late writers, and by moft of them fuppofed to be loft at this time j but this was wholly owing to their mithking the clafs of bo- dies among which they were tu look for it. Some imagining it to have been a fpecies of green marble ; and others the turquoife- ftone, that Diolcorides meant by this name. It is very plain however, that it was no other than an indurated clay of the morocbthus kind, and no more a ltone than that fubftance, that being alfo frequently called tapis morochthus. It is of a fmooth, even and regular texture, very heavy, of a mining furface, and of a pale green, without the admix- ture of any other colour, it does not at all adhere to the tongue, nor ftain the fingers in handling ; but drawn along a rough furface, leaves a flender white line. It melts flowly in the mouth, and is of a fharp acrid and difagreeable tafte ; and when rubbed down with water on a marble, it melts in- to a milky liquor of a pure white, not the leaft greennefs be- ing fenfible in it. It is found at prefent in the great mine at Goilelar in Saxony, and feems to owe its colour to particles of copper; to which alfo it owes the virtues attributed to it by Diofcorides, acting as a weak kind of verdigreafe. Hill's Hift. of Foff. p. 36. THYLACION, a word ufed by the antient medical writers, to exprefs the bag formed by the membranes of the fcetus at the orifice of the pudenda, before the birth. THYLLA, ©v>^.a., in antiquity, a feftival in honour of Venus.
Potter, T. I. p. 405. THYMALLUS, in ichthyology, the name of a fi(h of the truttaceous kind, called in Englifh the greyling, or umber. It is of a long and flatted body, the belly is fomewhat broad, and the back rigid and thin. It feldom exceeds a pound, or at the utmoft a pound and half weight. Its back is of a dufky browniih green, with a fomewhat bluifh caft inter- mixed, and its fides of a more blue fliining glofs with an ad- mixture of gold colour. The fcales are of a fort of rhom- boidal form, and the fide-lines are much nearer the back than the belly. The fides are variegated with black fpots placed irregularly ; but there are none of thefe near the tail. The back has two fins, and the tail is forked. The head is fmall, the eyes large and protuberant ; the mouth is mode- rately large, and the upper jaw larger than the under; it has no teeth, but the whole jaws are rough like a file- It is caught in the frefli rivers in the mountainous counties of England, and in the like fituations in Germany, and other kingdoms, and is one of the fineft tailed of all the frefli- water fifh, It feeds on worms, and fpawns in May. See Tab. of Fifties, N°. 31. and WMughby's. Hift. Pifc. p. 187. THYMBRA, in botany, the name of a genus of plants ; the characters of which are thefe : The flowers and feeds are in all refpects like thofe of thyme, but that they are placed ver- ticillately round the ftalks.
The fpecies of Thymbra, enumerated by Mr. Tournefort, are thefe: 1. The Thymbra, fimply fo called, and named by- others candy favor y. %. The Spanilh Thymbra, with leaves like marjoram, called marum, and majlichina ; and by ibme clinopodium. 3. The round ifh-leavcd Spanifh Thymbra, 4. The Spanifti Tliymbra, with leaves like the coris, called by (ome/erpillum ; and by others a fpecies of thyme. And, 5. The St. Julian Thymbra, or true favory, called alfo by fome fpiked favory, and the St. Julian's Savorv. Tourn. Inft. p. 197. 1 THYME,
