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f„. .n thf profcfforiJ chair of Rudbeck and L.nn^us at 

 Upfal. after having cffc.tially added to the general Hock of 

 knowledge by hi. Travels to Japan. h,s Moras of tha 

 country and of the Cape, and h.s very numerous academical 

 differtations. The liberal communications, and amiable cha- 

 rader of profeffor Thunbc-rg. have fecured him no lefs per- 



than his extenlTvc application and knowledge. 



rafter 



fonil elleem ...» . . . , -• 



His conftitution, though fhaken by a terrible misfortune in 

 his voyage, the accidental ufe of white lead in his food, 

 which proved fatal to fomc of his mefs-mates, has ftill car- 

 ricd him on to the advanced age of 73.— Retz. Aft. Lund. 

 V 1 i6v Linn. Suppl. 4^). Schreb. Gen. 426. Willd. 

 Sp PI. V. ^ 388. Mart. Mill. Dia. V.4. Ait. Hort. 

 kew. V. 4.65. Thunb. Nov. Gen. 21. Prodr. 106. 

 .luiT. 103. Lamarck lUuilr. t. 549. — Clafs and order, 

 DUjnamia yinglofptrmia. Nat. Ord. PerfmaU, Lmn. 

 Acanthi, JufF. 



Gen. Ch. Cal P.-rianth inferior, double, permanent: 

 the outermoll of two ovate, obtufe, ribbed, equal leaves, as 

 long as the tube of the corolla : inner of one leaf, in many, 

 about twelve, awl-lhaped ereft fcgments, not one-third fo long 

 as the former. Cor. of one petal, falver-lhaped : tube gra- 

 dually dilated upwards : limb in five deep, nearly equal, 

 obovate, very abrupt fegments, about half tlie length ot the 

 tube. Sliim. Filaments four, awl-fhapcd, inferted into the 

 tube, the two lower ones fliorteft, all included within the 

 tube ; anthers arrow-fliapcd. Piji- Germen fuperior, 

 roundifli ; ftyle thread-fhapcd, ereA, liardly fo long as the 

 tube ; ftigma of two rounded flat lobes. Perk. Capfule 

 globofe with a beak, fmooth, or two cells and two v.ilves, 

 burfting lengthwife : the beak linear, obtufe, comprelTed, 

 furrowed ; partition obovate, emarginatc, perforated below 

 the fummit, membranous at the ildes, permanent. Seeds two 

 in each cell, kidney-fhapcd, rugged, convex on the outl'ide, 

 concave on the inner, with a longitudinal furrow. 



E(r. Ch. Calyx double ; the outer of two leaves ; inner 

 in many awl-(haped fegments. Corolla falver-fliaped, with 

 five regular lobes. Capfule beaked, of two cells. 



Obi. Linnaus remai-ks that this genus agrees in many 

 points with Barler'ia. Thunberg takes the outer calyx- 

 leaves for brafteas, but this is not countenanced by the alto- 

 gether peculiar appearance of the inner calyx, by no means 

 like an external pcriantli. 



1. T.cnpenfis. DifFufe Thunbergia. Linn. Suppl. 292. 



Willd. n. 1. Retz. Aft. Lund. v. i. 163, witli a figure 



Leaves roundiih-ovate, obtufe. Stem diffufe. — Native of 

 the Cape of Good Hope. The root fecms to be perennial. 

 Stems a finger's length, diffufe, fimple, leafy, fquare, hairy. 

 Leaves oppofite, on (hort hairy ftalks, entire or fomewhat 

 toothed, hardly an inch long, ftrongly reticulated with 

 veins : very rough with minute briftlcs above ; haii^ be- 

 neath. Flowers yellow, on fimple, folitary, ftriated, ereft, 

 axillary, hairy Jlalis, twice the length of the leaves. Outer 

 ealyx very hairy ; inner rigid, with almoft pungent points. 

 Corolla about an inch long, its fegments fomewhat rounded. 

 Capfule rigid, about the fame length. 



2. T. fragrans. Twining Thunbergia. Roxb. Corom. 

 V. I. 47. t. 67. Willd. n. 2. Ait. n. i. Andr. Repof. 

 1. 123 — Leaves ovate -oblong, fomewhat hcart-fhaped, acute. 

 Stem twining — Common in hedges, ainong bufhes, on the 

 banks of water-courfes, about Samulcotah, "flowering in the 

 wet and cold feafons. Dr. Roxburgh never met with it 

 any where elfe. He fays the plant poii'efles a peculiar and 

 agreeable fragrance, and the beauty of its flowers, though 

 not fragrant, entitles it to a place in the flower-garden. 

 No fcent has been difcovered in any part of this plant in our 

 ttoves, where it blolToms freely all fummer long. The long 



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and twining fltms readily diftinguirti this fpecies from the 

 foregoing, as well as the elongated form of the leaves, which 

 are occafionally angular, or toothed, near the bafe. The 

 flowers arc white, larger, and with a narrower tube than the 

 capenfls, their fegments more abrupt or fomewliat notched. 



It appears by the Linn;ian herbarium that the younger 

 Linnxus had originally deiliiicd the name of Solandra for this 

 genus. J 



Another Thunbergia was previoufly eftablifhed by Dr. ^ 

 Montin, in the Stockholm Tranfaftions for 1773, but the 

 noble plant on which it was founded proved a Gardenia. 

 See that article. 



THUNDER, a noife in the loweft region of the air, ex- 

 cited by a fudden cxplofion of eleftrical clouds ; which, on 

 this account, are called thunder -clouds. 



Seneca, Rohault, and other authors, both ancient and 

 modern, account for thunder by fuppofing two clouds im- 

 pending over one another, the upper and rarer of which, be- 

 coming condenfed by a frefli acceffion of air raifed thither 

 by warmth from the low er parts of the atmofphere, or driven 

 upon it by the wind, immediately falls forcibly down upon 

 the lower and denfer cloud : by which fall the air interpofed. 

 between the two being comprefled, that next the extremities 

 of the two clouds is fqueezed out, and leaves room for the 

 extremity of the upper cloud to clofe tight upon the under ; 

 thus a great quantity of air is enclofed, which, at length 

 efcaping through fome winding irregular vent or paffage, oc- 

 cafions that noife which we call thunder. 



But this could only reach to the phenomena of thunder 

 heard without lightning ; and, therefore, recourfe has been 

 had to auother lolution. It has been faid, that thunder ii 

 not occafioned by the falling of clouds, but by the kindling 

 of fulpluirous exhalations, in the fame manner as the noife 

 of aurum fulminans. 



" There are fulphurous exhalations," fays fir Ifaac New- 

 ton, " always afcending into the air when the earth is dry ; 

 there they ferment with the nitrous acids, and fonietimes 

 taking fire, generate thunder, lightning, &c." 



That, befides the vapours raifed from water, &c. there 

 are alfo exhalations carried off from fulphur, bitumen, vola- 

 tile falts, &c. is paft all doubt ; the vail quantity of ful- 

 phurous and bituminous matter all over the furface of the 

 earth, and the volatile falts of plants and animals, afford 

 fuch an ample ftock of them, that it is no wonder the air 

 fhould be filled with fucli particles, raifed higher or lower, 

 according to their greater or lefs degree of fubtlety and afti- 

 vity ; and more copioufly fpread in this or that quai'ter, ac- 

 cording to tlie direftion of the winds. 



Now, the effefts of thunder are fo like thofe of fired 

 gunpowder, that Dr. Wallis thinks we need not fcruple to 

 afcribe them to the fame caufe ; and the principal ingre- 

 dients in gunpowder, we know, are nitre and fulphur ; 

 charcoal only ferving to keep the parts feparate, for their 

 better kindling. 



Hence, if w-e conceive in the air a convenient mixture of 

 nitrous and fulphurous particles, from the fources above men- 

 tioned ; and thofe, by any caufe, to be fct on fire, fuch 

 explofion may well follow,; and with fuch noife and light, 

 the two phenomena of thunder, as in the firing of gun- 

 powder ; and being once kindled, it will run from place to 

 place, this way or that, as the exhalations happen to lead it ; 

 much as is found in a train of gunpowder. 



This explofion, if high in the air, and remote from us, 

 will do no mifchief; but if near us, may deftroy trees, 

 animals, &c. as gunpowder would do in the like circum- 

 ftances. 



This nearncfs, or diftance, may be eftimated by the in- 

 terval 



