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limc-llone of that dillria is interfoctixl by numerous per- 

 pendicular metallic veins, wliich rife from the loweil lime- 

 ilone to the uppermotl ; but on finking through the vein in 

 the firll limc-ilone, down to the firil toad-llonc, the vein will 

 entirely difappear, but on perforating through the toad- 

 ftone, it will be found again in the fecond limc-llone; and 

 the fame appearances will be prefentcd on piercing through 

 tlic fecond and third beds of lime-llone, and the fecond and 

 third beds of toad-ftone. See Plate IV. Geology, Jig. l. 

 where I, 2, 3, 4, reprefent the four beds of lime-ilone ; 

 h, h, i.^the three beds of toad-ftonc ; and -u, v, v, v, the 

 metallic vein pafling through the different lime-ilone beds, 

 but completely cut off or llparated by tlie intervening beds 

 of toad-ftonc. ' To account for this interruption of the vein 

 at V, V, V, Mr. Whitehurll fuppofcs tliat the toad-ftonc, in a 

 ftate of igneous fnfion, has burft through the lower ftrata, 

 and has forced itfelf between the ftrata of limc-ftonc by a 

 lateral motion. Were this the cafe, we muft admit that the 

 toad-ftonc had rifen through filTures or dikes, fimilar to what 

 exift in many of the northern parts of Britain, and are called 

 vrhin-dikes. The whin-ftone, or bafalt, bearing a clofe 

 refcmblance to toad-ftonc, and the ftrata in the peak of 

 Derbyfhire being mucli fraftured, we fliould feel little 

 difficulty in admitting the probability of Mr. Whitehurft's 

 theory, did it apply to the different phenomena which thefe 

 beds of toad-ftoiie prefent. According to this theory, the 

 beds of toad-ftone muft have been interpofed fubfequently to 

 the formation of the metallic veins. There are, however, in- 

 ftances, in which very large veins extend from the lime-ftone 

 to fome depth in the toad-ftone, and terminate in fmall 

 ftringsof ore ; in other inftances, though the ore is not con- 

 tinued through the toad-ftone, a fmall vein filled with fpar 

 may be traced from No. i. the firft lime-ftone, through b, to 

 No. 2. the fecond lime-ftone. Such inftances prove, in the 

 moft decifive manner, that the formation of the veins was 

 pofterior to that of the toad-ftone. Hence we are led to 

 feek for fome other caufe which may explain the abfence of 

 metallic ores in the beds of toad-ftone. This fubjeft will be 

 confidered when we treat of metallic veins. See Trap, and 

 Veins, Mineral and Metallic. 



From the experiments of Dr. Withering on this ftone 

 with different acids, alkalies, and by fufion, it appears that 

 one hundred parts of it confift of 63I parts of filiceous earth, 

 16 of calciform iron, 7 J- of calcareous earth, and 14^ of 

 earth of alum. The aggregate of thefe ingredients is found 

 to weigh i^ parts more than the original mafs, which is 

 afcribed to the fubftance capable of uniting with fixable air, 

 not having been fully faturated with it, as they would be 

 after their precipitation by the earth of alum. { Phil. Tranf. 

 vol. Ixxii. part ii. p. 353.) This fubftance differs httle from 

 bafaltes : it is fofter, contains a fmaller proportion of iron, 

 and a larger of filex. 



TOAGAMALLY, in Geography, a town of Hin- 

 dooftan, in the Carnatic ; 17 miles W.S.W. of Trit- 

 cliinopoly. 



TOAHOUTA, one of the fmaller Society idands, near 

 Otaha. 



TOAIREH, a town of Egypt, on the coaft of the Red 

 fea, where the water is fait ; 3 miles N. of Kolzum. 



TOALDO, Joseph, in Biography, a diftinguifhed phi- 

 lofopher, was born in 17 19 at a final! village near Marof. 

 tica, in the valley of Vicenza, at the foot of the Alps, and 

 fcnt, in the year 1733, to the feminary of Padua, where he 

 ftudied Latin, rhetoric, philofophy, tlieology, and parti- 

 cularly mathematics. In this feminary he afterwards be- 

 came n teacher of grammar, rhetoric, philofophy, and 

 mathrmatics. His firft literary work was a new edition of 



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the writings of Galileo, to which he added feveral fragments 

 ncTcr before publifhed, with a preface and notes. For his 

 ferviccs to the above-mentioned feminary he was recom- 

 penfed with the benefice of Montcgalda, which he enjoyed 

 for 14 years, and wliich he cxchimged for another more 

 convenient, after his appointment by the fenate of Venice, 

 in 1762, to the profcfforftiip of aftronomy and meteorology 

 in the univerfity of Padua. Here he conftrufted an ob- 

 fervatory, begun in 1767 and completed in 1774. In 1769 

 he publifhed at Padua a fliort view of plane and fpherical 

 trigonometry, entitled " Tavole Trigonometriche, Sec." 

 which was reprinted and ufed in many of the Italian femi- 

 naries. He next publiftied atreatife on the influence of the 

 heavenly bodies on the weather and atmofpherc, containing 

 the refult of a lojig feries of meteorological obfervations. 

 This work, printed at Padua in 1770, 4to., was tranflated 

 into difterent languages, and fo w.ll received, that he was 

 admitted into various learned fucieties. About the fame 

 time he prefented to the public effays in favour of eleftrical 

 conduiftors, which caufed them to be erefted in the Venetian 

 territories ; alfo a chronological view of uncommon changes 

 in the weather, with tables of the ftate of the barometer, 

 and the flux and reflux of the fea. His meteorological 

 journal was begun in 1773, and continued till his death. 

 His celebrity was augmented in 1774 by an anfwer to a 

 prize queftion, propofed by the academical fociety of Mont- 

 pelier, on meteorology applied to agriculture ; and after 

 this time he laboured inccflantly in diffufing meteorological 

 fcience. In 1777 he tranflated Lalande's Aftronomical 

 Tables, and his " Abr^ge de I'Aftronomie ;" and fome 

 time after, his " Aftronomie des Dames ;" erefting alfo in 

 his obfcrvatory a marble buft of that eminent aftronomer. 

 From this time he almoft reftrifted his attention to aftro- 

 nomy and meteorology, endeavouring to confirm his hypo- 

 thefis of the influence of the moon on the different changes 

 of the weather. He alfo publiflied an hiftorical view of the 

 fervices rendered by the Venetian fchools to aftronomy, 

 geography, and navigation. In 1783 he obtained, in con- 

 jundlion with his nephew Chiminello, who was his afliftant 

 in the obfervatory, the prize offered for the bell treatife on 

 the conftruftion of a comparative hygrometer; and in 1784 

 he publiftied a fmall work on the longitude, which was well 

 received. He proceeded regularly with his journal till the 

 year 1787, when a fmall woi-k in two ftieets was printed at 

 Venice ; and in the following year his Tables of Vitality 

 appeared at Venice and Padua. Of his travels in 1780 and 

 in 1 788, in the courfe of which he examined the place where 

 Hannibal croffed the Alps, the refult was inferted in his 

 difl'ertation on the fubject, printed in the fourth volume of 

 the Tranfaftions of the Academy of Padua. But our limits 

 will not allow us to give even the titles of the numerous 

 effays and papers which he publiftied on various fubjefts, 

 relating principally to meteorology. The journals of the 

 period in which he lived contain many curious pieces con- 

 tributed by this induftrious inquirer into the operations and 

 phenomena of nature. Befides his publications, he left 

 in MS. feveral papers, and pai-ticuhtrly obfervations on the 

 travels of Marco Polo, and on the real epoch of the 

 Chinefe wall. The termination of Toaldo's life was acce- 

 lerated by the chagrin which he felt, in confequence of a 

 fruitlefs attempt to ferve a young man who had been de- 

 prived of his ofiice. This irritation affefted his health, fo 

 that in November, 1797, he was attacked by a nervous af- 

 feftion, which in a few days proved fatal, in the 79th year 

 of his age. 



" Toaldo," fays his bipgrapher, '< was of fmall ftature ; 

 but, in general, had an engaging appearance that infpired 



confidence 



