V E R 



V E R 



a repetition of obfcivatioiis on the repeating circle ; for, by 

 the mode in which Troughton's circular inflruinents are 

 ufcd, the readings will be had at fix different points of the 

 circle, though very little time is expended in making the 

 obfervations. It is hardly neceiTary to add liere, that when 

 an inftr,ument is of the refledling kind, its divilions are 

 doubly numerous for the fame radius, when compared 

 with an inftrument that meafures only by diredl vifion ; and 

 that therefore the divifions on the vernier mud be calculated 

 to have their dimenfions accordingly. In Troughton's re- 

 flefting circle of five inches radius, the degree is divided into 

 three parts, and fifty-nine of thefe are commenfurate with 

 fixty on the fcale of each of the three verniers ; therefore 

 the excefs of a fpace on the limb over, one on the 'Vernier is 



IO° 40' 70800" „ , . , . , r „ n 



— — = = 20 , which IS the Imallelt quantity 



59 X 60 3540 



that a fingle vernier will indicate ; but as there are fix read- 

 ings in the crofled obfervation, which obfervation annihilates 

 the errors of zero, and of the darkening glafles when ufed, 

 it is to be inferred that the rcfult will be accurate to 



20" 



-— , or little more than tLres feconds, if we difregard the 



probable errors of reading, and of taking contafts in the 

 obfervation, common to all inftruments. The figures of 

 the vernier fcales in this circle count both ways, from each 

 end, becanfe the figures read both to the right and left of 

 zero on the limb, but there can be no miftake if the figures 

 of the vernier are counted the fame way that the liml) of the 

 circle reads. Formerly the zero of the vernier was placed 

 at the middle of its fcale ; and when it read out at one end, 

 it commenced at the other, and finifhed again in tlie middle ; 

 but this method, being liable to mifapprehenfion, is now 

 difcontinued. 



In an eighteen -inch aflronomical circle, by Troughton, at 

 prefent under our examination, which has four verniers at 

 equal diftances, and turns in azimuth, the degree is divided 

 by Engine into twelve divifions, of which 59 fill the fame 

 arc as 60 on the verniers refpeftively ; hence we have 59 x 5' 

 ^ 295', or 17700" for the numerator, and 59 x 60 = 



q", the fmalleft 



? ?40 for the denominator, and • 



354° 



quantity that one vernier will indicate ; and accordingly 

 the fpace between zero and i' on the vernier is fiibdivided 

 in 12 fmaller fpaccs, fo that each fucceflive coincidence will 

 mark out 5" on each feparate vernier ; but as there are four 

 verniers, and as the circle will rcverfe in pofition iiy means 

 of the azimuthal motion, there will be virtually eight read- 

 ings from which to take an average of 5", fo that the pro- 

 bable accuracy rcfulting from fuch average comes ivilhin the 

 fecond, and would have done fo if there had been only three 

 verniers. Hence the advantage gained over the average of 

 the verniers by microfcopic readings, is probably not fo great 

 as is generally fuppofed. 



VERNIO, in Geography, a town of Etruria ; 1 1 miles 

 N.W. of Pifloya. 



VERNIS Maktin. See Co/a/ Varnish. 



VERNISH. See Varnish. 



VERNISSON, in Geography, a river of France, which 

 runs into the Loing, near Montargis. 



VERNODUBRUM, in /Indent Geography, a river of 

 GaUia Narbonnenfis. Pliny. 



VERNOIL, in Geography, a town of France, in the 

 department of the Mayne and Loire ; 14 miles S.E. of 

 Bauge. 



VERNON, in Bingrnphy, an Englifli finger, brought up 



at St. Paul's under Savage, was felefted from among the 

 chorillers of that cathedral, in 1750, to perform the part of 

 Puck the fairy in Queen Mab. When his voice broke into 

 a tolerable tenor, he was engaged at Drury-lanc theatre to 

 fupply the place of Lowe, who was degraded into a finger 

 at Sadler's Wells and Cuper's Gardens. Vernon, with a 

 voice much inferior to that of Lowe at his beft, was a mucli 

 better mufician and adlor, and had not only all Lowe's parts 

 afligned to him at Drury-lane, but fucceeded him at Vaux- 

 hall, where, and at the theatre, he continued to perform till 

 the time of his death. 



Vernon was not only the profefiional fucceflbr to Lowe, 

 but heir to his imprudence and debauchery. 



Vernon, in Geography, a town of France, in the depart- 

 ment of the Eure, on the fouth fide of the Seine ; 15 miles 

 E.N.E. of Evreux. 



Vernon, formerly Hinfdah, a town of America, in Wind- 

 ham county and ftate of Vermont, on the W. bank of Con- 

 nefticut river ; containing 1 159 inhabitants. — Alfo, a town 

 of Suflex county, in the Hate of New Jerfey, 2 1 miles N.E. 

 of Newtown ; containing 1 708 inhabitants. — Alfo, a town 

 of Trumbull county, in the diftrift of Ohio ; containing 

 606 inhabitants. 



Vernon, Mount. See Mount Vernon. 



VERNONBURG, a town of the ftate of Georgia ; 1 1 

 miles S. of Savanna. 



VERNONIA, in Botany, was fo named by Schreber, 

 in memory of Mr. William Vernon, fellow of St. Peter's 

 college, Cambridge, who towards the end of the fevcnteenth 

 century made a voyage to Maryland, in company with Dr. 

 David Kreig, a German phyfician, of which botany was 

 the principal objeft. Their herbarium, confifting, it is faid, 

 of feveral hundred new plants, came into the pofieffion of 

 fir Hans Sloane, and contributed to enrich the iupplcment, 

 or third volume, of Ray's H'ljlorui Plantarum. A North 

 American genus therefore is peculiarly proper to comme- 

 morate Mr. Vernon ; whofc merits as an accurate and in- 

 duftrious EngHfh botanift are, moreover, recorded by Ray 

 in the preface to his Syttopfis, ed. 2d, and his name often 

 occurs in the cryptogamic part of that work. We find no 

 further mention of this gentleman, nor does he appear any- 

 where as an author Schreb. Gen. 541. Willd. Sp. PI. 



V. 3. 1632. Mart. Mill. Dift. v. 4. Ait. Hort. Kew. v. 4. 

 502. Michaux Boreal. -Amer. v. 2. 94. Purfh 511 — 

 Clafs and order, Syngenefia Polygamia-itquaUs. Nat. Ord. 

 Compofita capitatte, Linn. CinarocephaU, Juff. 



Gen. Ch. Common Calyx ovate, imbricated, with nume- 

 rous, ovato-lanceolate, pointed, coloured fcales. Cor. com- 

 pound, uniform, all the florets, tubular, equal and perfeft, 

 of one petal, funnel-fliaped ; the tube inflexed ; limb with 

 five recurved fegments. Stam. Filaments five, capillary, 

 very (hort ; antliers united into a cylindrical tube. P'lJI. 

 Germen oblong ; flyle thread-fliaped, the length of the fta- 

 mcns ; ftigmas two, reflexed. Peru, none, the calyx re- 

 maining unchanged. Seeds folitary, ovate. Down capil- 

 lary, coloured, feflilo, longer than tlie calyx, furrounded at 

 its bafe witli a vej-y (hurt crown, of many chaffy brillles. 

 Recept. naked, flat. 



Elf. Ch. Receptacle naked. Calyx ovate, imbricated. 

 Florets tubular, five-cleft. Seed-down double ; the outer 

 chaffy, fliort ; inner capillary. 



The fpecies of this geiuis, as far as they were known to 

 Linnarus or JulTieu, were referred by both to Sehratula ; 

 fee that article and Liatri.s. Thefe genera differ very 

 clearly from Vern'miii in their featlicry feed-down, deftituie 

 of furrounding fcah s or brillles, and the firll of them has, 

 moreover, either a fcaly or a villous receptacle. Seven fpo 



cics 



