S E M 



greater and lefs tone of the natural fcale, which divides it 

 into two (emitoncs nearly equal. Thus, the greater tone 

 8 : 9 is divided into two femitoncs, which are i6 : 17, and 

 17 : i8 ; where 16:17: 18, is an arithmetical divifion, the 

 numbers reprefenting the lengths of the chords ; but if 

 they reprefent the vibrations, the lengths of the chords are 

 reciprocal ; wz. as i : | f : 4 5 which puts the greater femi- 

 tones 4-f next the lower part of the tone, and the lefTer -!-J 

 next the upper, which is the property of the harmonical di- 

 vifion. And after the fame manner the lefs lone 9 : 10 is 

 divided into the two femitones 18 : 19, and 19 : 20; and 

 the whole oftave Hands thus : 



m- 



d. d^. e. f. /«. g. S¥:- 



b. 6. 



This fcale, Mr. Salmon tells us, in the Philofophical 

 Tranfadlions, he made an experiment of, before the Royal 

 Society, on chords, exaftly in thefe proportions, which 

 yielded a perfedt concert with other inllruments, touched by 

 the belt hands. Mr. Malcolm adds, that, having calculated 

 the ratios thereof, for his own fatisfaftion, he found more 

 of them falfe than in the preceding fcale ; but then their 

 errors were confiderably lefs, which made amends. Mal- 

 colm's Mufic, chap. X. § 2. 



SEMIVOWELS, in Grammar. See Consonants. 

 SEMIVULPA, in Zoology, a name hy which Gefner, 

 and fome others, have called the opoHum. 



SEMIZUS, \n Ancient Geography, a town of LefTer Ar- 

 menia, in Melitene. Ptolemy. 



SEMLIN, in Geography. See Zemlin. 

 SEMLYO, a town of Hungary ; iz miles W.N.W. of 

 Stuhl Weiflenburg. 



SEMMARA, a town of Naples, in Calabria Ultra ; 10 

 miles W. of Oppido. 



SEMMYA, a town of Hindoollan, in Bahar ; 14 miles 

 N. of Bahar. 



SEMNAN, a town of Perfia, in the province of Comis ; 

 40 miles S.W. of Damegan. 



SEMNEON, in Ancient Geography, a town and epifco- 

 pal fee of Afia, in Pamphylia. 



SEMNI, a race of philofophers in India. 

 SEMNO, in Geography, a river of Albania, which runs 

 into the Adriatic ; 4 miles W. of Canovia. 



SEMNONES, a people of Germany, who, according to 

 Tacitus, boatted of being the mod noble among the Suevi. 

 SEMODIUS, among the Romans, a meafure equal to 

 half the modus, or the fixth part of the amphora. 



SEMONES, among the Ancients, a clafs of gods that 

 were of a middle nature between the celeitial and terreftrial 

 gods. Jultin Martyr has miftaken one of thefe for Simon 

 Magus. Mem. de I'Acad. des Infcrip. vol. i. p. 270. 



SEMOVNIE, m Geography, a town of European Tur- 

 key, in Bulgaria; 12 miles W. of Nicopoli. 



SEMOY, a town of France, in the department of the 

 Forells ; 5 miles N.W. of Chiny. 



Semoy, a river of France, which rifes near Arlon, and 

 enters the Meufe near Chiteau Renard, in die department 

 of the Ardennes. 



SEMPACH, a town of Switzerland, and capital of a 

 bailiwick, fituated on a lake to which it gives name ; 7 

 miles N.W. of Lucerne. — Alfo, a lake of Switzerland, ia 

 the canton of Lucerne, fix miles long and two wide ; 8 miles 

 N.W. of Lucerne. 



SEMPERVIVjE, in Botany, a natural order of plants, 

 Co termed from one of the principal genera ; as alfo per- 

 haps, more efpecially, in allufion to the tenacioufnefs of the 

 living principle, common to the whole order, and to which 

 the faid genus owes its name. See Sempervivum. 

 Vol. XXXII. 



8 E M 



This is the 83d of JuJTieu's orders, the lirft of his 14th 

 clafs, whofe charafters may be found at length ui der the 

 article Ficoide^e. The Semper-viv^ are dchned as follows. 



Calyx inferior, divided deeply into a d/finite number of 

 fegments. Petals inferted into the bottom of the calyx, 

 alternate with its fegments, and agreeing with them it: num- 

 ber, or more rarely the corolla is nionopetalous, either tubu- 

 lar, or deeply divided. Stamens either as many as tin piials, 

 and alternate therewith ; or twice as numerous, inferted al- 

 ternately into the claws of the petals, and the bottom of 

 the fegments of the calyx ; anthers roundifh. Germens 'Seve- 

 ral, equal in number to the petals, joined togethei by the 

 internal angle of their bafe, glandulai at the oppofite part, 

 their glands, in fome inftances, affuming the form of fcalcs ; 

 ftyles and (ligmas as many as the germens. Capfules as many, 

 of one cell, with many feeds, feparating at the inner margin 

 into two valves, whofe edges bear the Jeeds. Corculum in- 

 curved, furrounding a farinaceous mafs. Stem herbaceous, or 

 foinewhat fhrubby. Leaves oppofite or alternate, fnccnlent. 



The genera are Til/iea, Crajfula, Cotyledon, Rhodiola, Se- 

 dum, Sempervivum, and Septas ; to which Penthorum is fub- 

 joined, as akin to the reft, but differing in habit, (as being 

 not fucculent,) and in " the mode in which the capfule 

 burfts ;" fee Penthorum, where Juflieu's miftake is rec- 

 tified, and this genus referred to the order in quellion, with- 

 out any exception or doubt. 



SEMPERVIVUM, a name which immediately befpeaks 

 its own derivation, femper vivexs, ever-living, or evergreen ; 

 the plants which compofe this genus being from their very 

 fucculent nature fo extremely tenacious of life. — Linn. Gen. 

 244. Schreb. 329. W^iUd. Sp. PI. v. 2. 930. Mart. Mill. 

 Dift. V. 4. Sm. Fl. Brit. 522. Prodr. Fl. Grxc. Sibth. 

 V. I. 334. Ait. Hort. Kew. v. 3. 171. .Tufl. 307. La- 

 marck Uluftr. t. 413. Gaertn. t. 65. — Clafs and order, 

 Dodecandria Dodecagynia. Nat. Ord. Succulents, Linn. 

 Sempervi-va, Juli. 



Gen. Ch. Cal. Perianth inferior, permanent, deeply 

 cloven into about twelve, concave, acute fegments. Cor. 

 Petals twelve, oblong, lanceolate, acute, concave, a little 

 larger than the calyx. Neftaries ufually wanting. Stam. 

 Filaments twelve, (lenderly awl-(haped ; anthers roundifh. 

 Pi/l. Germens twelve, fuperior, placed in a circle, ereft, 

 terminating in the fame number of fpreading ftyles ; iligmas 

 acute. Peric. Capfules twelve, oblong, comprefled, fhort, 

 ranged circularly, pointed outwardly, opening inwardly. 

 Seeds numerous, roundifh, fmall. 



Efl'. Ch. Calyx inferior, in twelve deep fegments. Petak 

 twelve. Capfules twelve, with many feeds. 



Obf. Linnius in a remark under the natural charafter 

 in his Gen. PI. makes the greater number of petals the 

 effential dillinftion between this genus and Sedum, but in the 

 Sy/l. Feg. the neftariferous fcales are properly made charac- 

 terillic of tiie latter. According to this principle, Semper- 

 vivum fediforme , of Jacquin, has been referred by fir J. E. 

 Smith, in Tr. of Linn. Soc. v. 10. 6, to Sedum, with which 

 it accords alfo in habit, differing altogether from Sempervi- 

 vum, except in number of petals, &c. a circumllance 

 known, in this cafe, to be uncertain. Neverthelefs, there 

 being in Sempervivum hirtum, according to Schmidcl's figure 

 at leaft, a minute indication of a fcale, or tooth, at the bafe 

 of each gcrmcn, the learned editor of Hort. Kew. was in- 

 duced, on that ground alone, to prefer the charafter de- 

 duced from number, in the above plant of Jacquin. Both 

 Willdcnow and Martyn enumerate fourteen fpccics of this 

 handfome genus, including Sediformc ; many of thefe arc 

 beautifully figured by Jacquin and Curtis. The fnllowing, 

 beginning with the only Britifh fpccies, may fcrve as an 

 epitome of the whole. 



F f S. uaorum. 



