T H U 



T H U 



no certain and fatisfaftory accounts ; and others again liave 

 been of opinion, that no iOanJs to whicli modern voyagers 

 have liad accefs, correfpond more exaftly to their reports 

 than the ifles of Shetland, N. of Scotland. See Zet- 

 land IJhmdi. 



Thui.k, in Geography, a town of Weftphalik, in the bl- 

 Ikopric of Paderborn ; 6 miles W.S.W. of Paderborn. 



Tiuhe, a river of Wales, in the county of Glamorgan, 

 whicl) runs into the Lloghor, near its mouth. 



Thulk, Southern, a part of Sandwich Land, obferved by 

 Capt. Cook in January 1775, in S. lat. 59° 13' 30" and W. 

 long. 27° 45', and fo called becaufe it is the moft fouthern 

 land that has ever yet been difcovered. It exhibits a furface 

 of vaft height, and is every where covered with fnow. Some 

 thought that they faw land in the fpace between Thule and 

 Cape Briltol : Cook thought it more than probable that thefe 

 two lands are conuefted, and that this fpace is a deep bay, 

 which he called Forfter's bay. 



THUM, a town of Saxony, in the circle of Erzgebirg ; 

 7 miles S. of Chemnitz. N. lat. 50° 37'. E. long. 12° 

 50'. — Alfo, a town of Bavaria, in the bifhopric of Bam- 

 berg ; 3 miles S.S.W. of Forcheim. 



THUMATA, in Ancient Geography, a town of the 

 Arabs, placed by Pliny on the banks of the Tigris, at a 

 confiderable diftance from the town of Petra. 



THUMATHA, atown fituated in the interior of Arabia 

 Fehx, between Chabuati and Olaphia. Ptol. 



THUMB, PoLLEX, in Anatomy, one of the members or 

 parts of the hand. See Extremities. 



Thumb-S/^//, a ferrule made of iron, horn, or leather, 

 with the edges turned up, to receive the thread in making 

 fails. It is worn on the thumb to tighten the ftitches while 

 fewing. 



THUMELITHA, in Ancient Geography, a town of 

 Africa, in Interior Libya, near the fource of the river Ci- 

 nyphis. Ptol. 



THUMEREVILLE, in Geography, a town of France, 

 in the department of the Mofelle ; 6 miles S.W. of 

 Briey. 



THUMERSTONE, in Mineralogy; Axinite, Haiiy. 

 This mineral was called Thumerftone by Werner, from 

 Thum, in Saxony, the place where it was found ; and Axi- 

 nite by Haiiy, from the flattened (harp edges of the cryftals 

 refembling the edge of an axe. This is the firft charafter 

 which ftrikes the eye when this mineral is prefented for in- 

 fpeftion. It is moft commonly found cryftallized, but 

 fometimes maffive or dilTeminated. The form of the cryf- 

 tals is a very comprefTed oblique rliomboidal prifm. The 

 primitive cryftal, according to Haiiy, is a four-fided prifm, 

 whofe bafes are parallelograms with very oblique angles : 

 the larger angle being 101.32, and the fmaller 78.28. In 

 the fecondary cryftals, the acute edges are generally trun- 

 cated. It is cryftalhzed alfo in obhque four-fided tables. 

 The form of the cryftals is fometimes very difficult to be de- 

 termined ; they not unfrequently interfeft one another, form- 

 ing a cellular aggregation. The external luftre is generally 

 fplendent ; Internally it is gliftening or fliining, and is vitre- 

 ous. It is tranfparent or tranflucent. The frafture is 

 fine-grained and uneven ; in the tranflucent varieties, it 

 fometimes approaches to fplintery ; and in the tranfparent 

 varieties, to the fmall and imperfeftfy conchoidal. It 

 fcratches glafs ; is harder than felfpar, but not fo hard as 

 quartz ; it is fragile, and fufible by the blow-pipe into a 

 greenifli-white glafs, but if laid on charcoal into a black 

 glafs. The fpecific gravity is from 3.2 to 3.3. The 

 colours of this mineral are moft commonly a clove-brown of 

 various degrees of intenfity, inclining to violet and green. 



Vol. XXXV. J" B g 



It is fometimM green and opaque : according to Brongniart, 

 this is owing to a mixture of chlorite. It has been ob- 

 lervcd, he remarks, that the cryftals which are coloured 

 with this earth arc the moft regular. The conftituent parts 

 are given by Klaproth and Vauquehn as under. 



Kliiprnth. Vauqueliii. 

 Silex - - - 52.70 and 50.50 44 



Alumine - - 25.79 '6. i8 



Lime - - 9.39 17. 19 



Oxyd of iron - 8.63 9-50 '4 



Oxyd of manganefe i. ^.z^ 4 



Potafli 



0.25 



This mineral occurs in Saxony, France, Switzerland, 

 and Spain, and at mount Atlas, in Africa. It is found alfo 

 mafTive and cryftallized near St. Juft, in Cornwall, at the 

 Botellock mine, aflbciated with common garnet, and in veins 

 between Marazion and Penzance. 



The moft beautiful variety is met with in a rock of fer- 

 pentine, near Balme d'Auris, in Dauphiny, in the depart- 

 ment of the IfSrc, where it generally occurs in well-defined 

 cryftals, fometimes colonrlefs and tranfparent, but more 

 frequently of a dull reddifli-violet colour, whence it ob- 

 tained the name of violet fchorl of Dauphiny. The cryf- 

 tals of thumerftone, which are not fymmetrical, become 

 eleftric by heat : it is indeed a general law, that all minerals 

 which poflefs tlie pyro-elettric property, are defeftive in 

 the fymmetry of the cryftals. 



THUMLITZ, in Geography, a river of Saxony, which 

 runs into the Mulda ; 3 miles S. of Grima. 



THUMMIM, in the Scripture Learning. See Uhim and 

 Thummim. 



THUMNA, in Ancient Geography, the name of two 

 towns fituated in the interior of Arabia Felix ; one between 

 Mochura and Aluare, and another between Mariama and 

 Vodona. Ptol. 



THUN, in Geography, a town of Switzerland, in the 

 canton of Bern, at the diftance of about 1 2 miles from the 

 town of Bern. It occupies the bottom and brow of a hiD, 

 and ftretches on both fides of the Aar. It contains 1200 

 inhabitants, enjoys confiderable immunities, has its own ma- 

 giftrates and courts of juftice, in which the bailiff from Bern 

 alw-ays prefides, and from whofe decifion an appeal always 

 lies to the capital. The inhabitants employ themfelves in 

 carding and fpinning filk for the manufaftures of Bafle. 

 Some of the burghers poflefs large herds of cattle. To the 

 N.E., on an eminence, ftand the church, and the caftle, which 

 is the refidence of the baiUfF. N. lat. 46° 44'. E. long. 

 7° 31'. — Alfo, a lake of S\<atzerland, in the canton of 

 Bern ; about four leagues long, and one broad, and pro- 

 bably very deep : the borders are richly variegated, and pre- 

 fent feveral fine points of view, much heightened by many 

 rugged rocksrifing boldly frona the margin of the water. The 

 river Aar pafles through the lake of Bricntz, and then en- 

 ters that of Thun, from which it is again difcharged, pafling 

 between two level promontories, prettily fprinkled with 

 trees, on one of which ftands the caftle of Schadao ; 15 

 miles S.S.E. of Bern. 



THUNA, a town of Cachemire ; 45 miles S. of Ca- 

 chemire. 



THUNBERGIA,in5ote«)',receivedthatname firft from 

 profeffor Retzius, and next in the Supplementum Plantarum, 

 from the pen of the younger Linnaeus, in honour of their 

 mutual friend, fir Charles Peter Thunbeig, knight of the 

 order of Wafa, by whole difcoveries that work was pecu- 

 liarly enriched with new and curious fpecies, efpecially from 

 the Cape of Good Hope. This illuftrious veteran ftill 

 4 F » fits 



