V I R 



V I R 



mony ; red, of acidity or aftringency ; black, of a noxious 

 quality. Even this lalt however is overruled by the infertion 

 of the ftamens into the calyx ; witnefs Prunas and Rites. 



Such are a f:w of the hints given by Linnseue. They are 

 well worthy of confideration, and may be extended or modi- 

 fied by praftical obfervation. Exceptions, of courfe, will 

 prefent themfelves, but fcarcely more than occur in any 

 other department of natural fcience. 



It is hardly necelTary to fay that the above rules relate 

 ■exclufively to the human conftitution. Some animals feed 

 on what are fatal poifons to others. The Goat and Deer 

 browze on the Clematis, which would blifter our throat, or 

 even our (Icin ; and dehght in the naufeous virulent feed ?f 

 the Horfe Chefnut. Infedls thrive on the moft bitter or 

 burning milky herbs or (hrubs, which no quadruped could 

 tafte with impunity. Nature teaches every animal what is 

 falutary to itfelf, and what is dangerous ; but man is capable 

 ■of reafon and fcience, to make experiments and obfervations, 

 and to enlarge the fphere of his knowledge by drawing 

 general conclufions. 



VIRTUOSO, A man pofleffed of talents in any of the 

 fine arts is called a virtuofo, but particularly in mufic, where 

 it ufually imphes a profefTor of talents. 



Among us, the term feems appropriated to thofe who 

 apply themfelves to fome curious and quaint, rather than 

 immediately ufeful art or ftudy : as antiquaries, colleftors 

 of rarities of any kind, microfcopical obfervers, &c. 



VIRTZ, in Geography, a lake of Ruflia, in the govern- 

 ment of Riga, about forty miles in circumference ; 96 miles 

 N.N.E. of Riga. 



VIRUCINATES, in Ancient Geography, a people of 

 Vindelicia, denominated Rucinates by Hardouin, who is juf- 

 tified in this reading by Ptolemy. 



VIRUELA, in Geography, a town of Spain, in Aragon ; 

 6 miles from Tarracona. 



VIRVESCA. See BiRViESCA. 



VIRULENT, a term applied to any thing that yields a 

 virus, that is, a contagious or malignant pus. 



The gonorrhoea virulenta is what we popularly call a clap. 



VIRUNI, in Ancient Geography, a people of Germany, 

 placed by Ptolemy with the Teutonari, between the country 

 of the Saxons and that of the Siievi. 



VIRUNUM, a town fituated in the northern part of 

 Germany, probably belonging to the Viruni, and fuppofed 

 by Cluvier to be the prefent Waren, in Mecklenburg. — 

 Alfo, a town of Norica, or ifle of Norica, in the middle of 

 the Danube, upon the route from Aquileia to Lauriacum, 

 between Santicum and Candalica, according to Anton. Itin. 

 In the table of Peutinger it is named Varenum. It is thought 

 that the emperor Claudius eftablifhed a colony in this place. 

 Cellarius fuppofes that this is the prefent Volckmarck, m 

 Carinthia. 



yiRUPAKSHA, in Mythology, a name of the Hindoo 

 <leity Siva ; which fee. It is faid to mean with three eyes, 

 fimilar to Trilokan ; vi'hich fee. The epithet Sri, or divine, 

 is commonly prefixed to this name. See Sri and Ski- 



VIRUPAKSHA. 



VIS, or ViSAY, in Commerce, a weight in the Eaft Indies, 

 which is the eighth part of the maund. See Maund. 



Vis, in Phyjiotogy, a term employed to denote the vital 

 powers : th'is, vis itijita is the contraftile power of a mufcle, 

 10 named becaufe it is inherent in the organization of the 

 part, and not dependent on any other influence : it is equi- 

 valent to vis irritabd'is. Vis nervea is that power of contrac- 

 tion which depends on the nerves. Vis vita is a general 

 <Kpreffion for the vital power altogether. See Life, Mus- 

 ctE, and Nervous S^/lem. 



Vis, a Latin word, fignifying force or power ; adopted by 

 phyfical writers, to exprefs divers kinds of natural power* 

 or faculties. See Force. 



This is aftive and paffive ; the vis aHiva is the power of 

 producing motion ; the vis pajjiva, that of receiving or 

 lofing it. The vis aSiva is again fubdivided into vit viva 

 and vis mortua. 



Vis Abfoluta, or ahfohti force, is that kind of centripetal 

 force which is meafured by the motion that would be gener- 

 ated by it in a given body, at a given diftance, and depends 

 on the efficacy of the cajfe producing it. 



Vis Accel^ratrix, or accelerating force, is that centri- 

 petal force which produces an accelerated motion, and is 

 proportional to the velocity which it generates in a given 

 time. 



This is different at different diftancea from the fame cen- 

 tral body ; and depends not on the quantity of matter that 

 gravitates, being equal in all forts of bodies at equal diftances 

 from the centre. See Acceleration. 



Vis Imprejfa is defined by fir Ifaac Newton to be the 

 aftion exercifed on any body to change its ftate, either of 

 reft or movi;;g uniformly in a right line. 



This force confifls altogether in the aftion ; and has no 

 place in the body after the aftion has ceafed. For the body 

 perfeveres in every new ftate by the vis inertia alone. 



The vis imprejfa may arife from divers caufes ; as from 

 p^rcuffion, prefiion, and centripetal force. 



Vis Inertia, power of inaSivity, is defined by fir Ifaac 

 Nev?ton to be a power implanted in all matter, by which it 

 refifts any change endeavoured to be made in its ftate, «'. e. 

 whereby it becomes difficult to alter its ftate, either of reft 

 or motion. 



This power, then, coincides with the vis rejijlendi, power 

 of refifting, by which every body endeavours, as much as 

 it can, to perfeverc; in its own ftate, whether of reft or uni- 

 form reftilinear motion ; which power is ftill proportional 

 to the body, and only differi from the vis inertia of the mafs, 

 in the manner of conceiving it. 



Bodies only exert this power in changes brought on their 

 ftate by fome ^i;r imprejfa, force impreffed on them. And 

 the exercife of this power is, in different refpefts, both re- 

 fiftance and impetus ; refiftance, as the body oppofes a force 

 impreffed on it to change its ftate ; and impetus, as the fame 

 body endeavours to change the ftate of the refifting obftacle. 

 Phil. Nat. Princ. Math. lib. i. 



The vis inertia, the fame great author elfewhere obfe/ves, 

 is a paffive principle, by which bodies perfift in their motion, 

 or reft, receive motion, in proportion to the force impreffuig 

 it, and refift as much as they are refifted. 



For the efFetl of the vis inertia, in refifting and retarding 

 the motion of bodies, &c. fee Resistance. 



Vis Infta, or innate force of matter, is a power of refifting, 

 by which every body, as much as in it lies, endeavours to 

 perfevere in its prefent ftate, whether of reft or of moving 

 uniformly forward in a right line. 



This force is ever proportional to that body whofe force 

 it is, and differs nothing from the vis inertia but in our man- 

 ner of conceiving it. 



Vis Centnpeta. See Centripetal Force. 



Vis Centrifuga. See Centrifugal Force. 



Vis Mo'.rix, or rioving force, of a centripetal body, is the 

 tendency of the whole body towards the centre, refulting 

 from the tendency of all the parts, and is proportional to 

 the motion which it generates in a given time, fo that the 

 vis motrix is to the vis acceleratrix, as the motion to the cele- 

 rity : and as the quantity of motion in a body is eftimated 

 by the produft of the celerity into the quantity of matter, 



the 



