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limits the diftance at which micronietrical meafurements 

 in loiiKimetry can be ufcfullv employed at one ilation. 

 What may be called the ot^liral error, or that which anles 

 from want of parallclilm in the rays of light on entermg the 

 obiea-jrlafs, and is allowed for in our fourth table, on the 

 contrarv, d-creafes with an incrcafe of diftance, and very 

 nearly in a fub-duplicate ratio ; fo that the corredion ariling 

 out of this optical error bjcoraes infenfible at no very great 

 diftance in tclefcopcs of ordinary dimenhons : for inftance, 

 at 220 vards, or its angle 15' 3S", the correaion is - 7 .4 

 by our'Tablc IV.; but at 440, or its angle 7' 49', the 

 correclion diminilhes to l".9, or nearly a fourth of the 

 former at double the diftance. Hence there is a peculiar 

 diftance at which every feparate telefcopc will have its 

 optical error or correaion reduced to 1", or quantity of 

 probable error of obfervation, beyond which diftance the 

 tabulated correftions may be difregarded in ordinary opera- 

 tions. With the telefcope of 63.5 inches focus, the cor- 

 reftion will be lefs than 1" at 590 yards diftance; with 

 that of 45.75 inches, at 537 ; and with that of 30.15 inches, 

 at 430, the diftance continuing to diminilh with the dimi- 

 niftiing length of the focus of each objeft-glafs, but not in 

 the fame ratio ; confcquently, when the telefcope is very 

 ftiort, and its power fmall, the optical error may be alto- 

 gether difregarded, wherever fucii telefcope can be of any 

 real ufe ; becaufe, in all probability, this error will be lefs 

 than the error of obfervation arifing from want of power. - 



Telescope Shell, in Comhology, the name of a fpecies of 

 turbo, with plane, ftriated, and numerous fpires. 



TELESCOPICAL Stak.s, fuch as are not vifible to 

 the naked eye, but difcoverable only by the help of a tele- 

 fcope. See Star. 



AH ftars lefs than that of the fixth magnitude are tele- 

 fcopic to a middling eye. 



TELESE, in Gcograf'hy, a town of Naples, in Lavora, 

 the fee of a bilhop, who reiides at Cerreto ; 18 miles E.N.E. 

 of Capua. N. lat. 41° 12'. E. long. 14" 32'. 



TELESIA, or Telessia, in Ancient Geography, a town 

 of Italy, in Samnium. 



Telesia, in Mineralogy. See CoRUNDUM. 

 TELESIO, Berkardino, in Biography, a modern phi- 

 lofopher, the defcendant of an illuftrious family at Cofenza, 

 in Naples, was born in the year 1508 or 1509. Having re- 

 ceived the early part of his education under an uncle at 

 Milan, he accompanied him to Rome in 1525, and ftiared 

 in the calamities which attended the fack and pillage of that 

 city. At Padua, whither he afterwards removed, he ap- 

 plied himfelf with diligence to the ftudy of mathematics and 

 philofophy. Returning again to Rome, he formed an inti- 

 mate acquaintance with feveral perfons of diftinguifhed cha- 

 rafter, and fo much ingratiated himfelf with pope Pius IV. 

 that he was offered the arclibiftiopric of Cofenza, which he 

 dechned for himfelf and obtained for his brother. From 

 Rome he retired to his native country, where he maiTied in 

 advanced age, and for a fiiort time became profefTor of phi- 

 lofophy in the univcrfity of Naples. However, the place 

 of his more conftant relidence was Cofenza, and here he 

 eftabliftied an academy called Cofentiiia. He paffed the re- 

 mainder of his life under the patronage of feveral perfons of 

 diftinftion, particularly Ferdinand, duke of Nocera ; but af- 

 flitled by the afTafTination of one of '.lis foiis, and by the ca- 

 lumnies circulated againft his fchool of philofophy, he ter- 

 minated hiB Hfe in the year 15SS. Telefio diftinguiftied him- 

 lelf by his oppofition to the phyfics of Ariftotle, and em- 

 ployed mathematical principles in explaining the laws of 

 nature. Theie were tirft divulged in a work printed at 

 Home in 1565, entitled " De Rerum Natura juxta propria 



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principia. Lib. II." and enlarged to nine books in an edition 

 printed at Naples in 1586. The fame fyftem was main- 

 tained in other treatifes, under the titles of " De his qua; in 

 Aerc hunt, et de Terrig Motibus ;" « De Mari ;" " De 

 Colorum Genere," &c. His fyftem was in its efl"ence the 

 doftrinc of Parmenides, who taught, that the firft principles 

 in nature, by means of which all natural phenomena are pro- 

 duced, are cold and heat. (See Parmenides and Eleatic.) 

 Teletio's theory is thus developed : " Matter, which is in 

 itfelf incapable of aftion, and admits neither of increafe nor 

 diminution, is afted upon by two contrary incorporeal prin- 

 ciples, heat and cold. From the perpetual oppoiition of 

 thefe, arife the feveral forms of nature : the prevalence of 

 cold in the lower regions producing the earth and terreftrial 

 bodies, and that of heat in the fuperior regions, the heavens 

 and celeftial bodies. All the changes of natural bodies are 

 owing to this conflid ; and according to the degree in which 

 each principle prevails, are the different degrees of denfity, 

 refiftance, capacity, moifture, drynefs, &c. which arc found 

 in different fubftances." This fyftem is founded on the 

 fanciful converfion of mere attributes and properties into 

 fubftaiitia! principles. For lord Bacon obferves, that Te- 

 lefio, no lefs than Plato and Ariftotle, places abftraft notions 

 at the bafis of his fyftem, and produces his world of real 

 beings from non-entities. This eminent pLilolopher, how- 

 ever, charafterifes him as a lover of truth ar.d a benefaftor 

 to fcience ; and one who prepared the way for fubfv-quent 

 improvements. After his death, his writings, as containing 

 " innovations," were put into the Index Expurgatorius of 

 the Inquifition. His philofophy, neverthelefs, had many 

 advocates, among whom was CampancUa ; and his works 

 were republiftied at Venice, in 1590, by Antonio Perfio, 

 who wrote a compendium of his philofophy in the vernacu- 

 lar tongue. Telefio's ftyle was more poliftied than that of 

 other philofophers of his time ; and he intermixed fome 

 Latin verfes of conCderable eloquence. Brucker by En- 

 field. 



TELESPHORUS, in Mythology, a deity invoked by 

 the Greeks for health, together with Efculapius and Hygeia. 

 The figures of thefe three divinities occur on feveral me- 

 dals ; and on fome we have Telefphorus with Efculapius 

 alone, and on others with Hygeia. 



The figure of Telefphorus is invariably the fame, viz, 

 that of an infant clothed with a fort of cloak without 

 fleeves, which enfolds its arms, defcends below the knees, 

 and has a kind of hood or cowl covering its head. 



Montfaucon has given a particular defcription of this 

 deity, the worihip of which is fuppofed to have paffed from 

 Epidaurus to Rome, with that of Efculapius. 



TELETiE, among the Ancients, were folemn rites per- 

 formed in honour of Ifis. 



TELETZKOI-Ozero, in Geography. See Altin. 



Teletzkoi Mountain, deriving its name from the lake 

 Teletzkoi-ozero, one of the greateft eminences of the Altay 

 mountains (fee Altai), and from which the river Oby 

 ifTues. It forms, with its lofty fummits, the boundary be- 

 tween Siberia and the Soongarey, ftrikes its powerful ridges 

 down between the lake and the Katunia ; and after having 

 turned round the eaft fide and the lake, unites with the Ku- 

 netzkoi mountains. This divifion is one of the greateft, but 

 at the fame time the coldeft and moft inacceflible, of all the 

 Altaian ore -mountains ; hence ■ it is, that its quality and 

 contents are little known. This, however, is certain, that 

 very powerful granite and porphyry mountains are in its 

 range, and that the earth near and upon it yields jafper, flint 

 breccia, hornfchiftus, white (probably faline) thalk-ftone, 

 coloured marble, black fchiiius, marie, fand-ftone, and in 



thefe 



