V E S 



VESUVIAN, in Mineralogy, {Idocrafe, Haiiy,) a mi- 

 neial originally found in the vicinity of Vefuvius, and clafled 

 by feme mincralogiils with the garnet family, of which it 

 forms a diftinft fpecies. It is generally cryftallized in four- 

 Cded prifms, the edges of which are truncated, forming 

 prifms with eight, fourteen, or iixteen fides, differently ter- 

 minated by low planes. The fides of the cryftals are ftreaked 

 longitudinally ; the terminating planes are fmooth. The 

 cryftals are generally middle-fi zed ; they occur in groups, 

 or lining cavities of other minerals. Vefuvian fometimes 

 occurs maflive. The colour of tins mineral is either a liver- 

 brown or reddi{h-brown, or blackifh or yellowifh-green. 

 The luftre of the cryftals is fplendent or vitreous. The 

 frafture is fmall-grained and uneven. It is more or lefs 

 tranflucent. It is fufEciently hard to fcratch glafs, but is 

 brittle. Vefuvian melts before the blow-pipe into a yel- 

 lowifh tranflucent glafs. The fpecific gravity varies from 

 3.36103.42. 



Ttie analyfis of Vefuvian gives its conftituent parts as 

 under : 



Frum Vrfuv'ms. From Siberia. 



Vefuvian has been found in various parts of Europe as 

 well as near Vefuvius : the opinions refpeAing its formation 

 will be referred to under Volcanic ProduHs. 



VESUVIAN.S1 Aqu;e, in Ancisnt Geography, the name 

 given by Tacitus to a fmall river of Campania, which 

 watered the town of Ncapolis. 



VESUVIUS, in Geography, a celebrated volcanic moun- 

 tain in Italy, fituated in the kingdom of Naples, about fix 

 miles SE. of the capital. Vefuvius appears an ifolated 

 mountain, ftanding in the middle of a plain, but is con- 

 fidered as connefted with the Apennines. The bafe of the 

 mountain is about 40 miles in circumference ; the height is 

 ftated at from 3700 to 3900 Englifti feet. Vefuvius has 

 two fummits ; the moft northern is called Somma, the other 

 is properly called Vefuvius. Somma is fuppofed, with much 

 reafon, to have been part of the cone of a larger volcano, in 

 which the prefeut volcanic cone of Vefuvius was formed. 

 " It is impoffible," fays fir James Hall, " to fee the moun- 

 tain of Somma, which in the form of a crefccnt embraces 

 Vefuvius, without being convinced tliat it is a fragment of 

 a larger volcano, nearly concentric with the prefent cone ; 

 which in fome great eruption lias dcltroyed all but this frag- 

 ment. In our own times, an event of no fmall magnitude 

 has taken place in tlie fame fpot : the inner cone of Vefuvius 

 having undergone fo great a change during the eruption in 

 1794, that it now bears no refcmblance to what it wa; in 

 1785." Tranfadlions of the Royal Society of Edinburgh, 

 vol. vii. 



From the building of Rome to the year 79 of the Chrif- 

 tian era, a period of feven centuries, Vefuvius appears to 

 have been in a ft ate of profound rcpofe, as no mention is 

 made of any eruption during the whole of that time ; and 

 the ancient writers who refer to this mountain always fpeak 

 of its extraordiriary beauty and fertility. There were, how- 

 ever, certain appearances near the funimrt which left no 

 doubt of its prior volcanic ftatc, and the cities in its vicinity 

 were paved with tlic lavas of ancient eruptions. 

 Vol. XXXVII. 



V E S 



Vitruvius, who flouriftied in the reign of Auguftus, fays 

 (lib. ii. cap. 6. ) " that Vefuvius had formerly been burning, 

 and had covered all the adjacent country' witli its fires." 

 Diodorus Siculus, who wrote at the latter end of the fame 

 reign, refers to a tradition of a volcanic eruption of Vefu- 

 vius feen by Hercules. Strabo, a contemporary writer, 

 defcribing this mountain, fays, " here rifes Vefuvius, inha- 

 bited through all its dehcious fields, the fummit alone ex- 

 cepted, which fpreads into a barren plain, difplaying afhes 

 and caverns formed of burnt rock ;" whence it may be con- 

 jeftured, that this fummit was formerly in a ftate of confla- 

 gration, and prefented fiery craters, which became extin- 

 guifhed when the materials were exhaufted. Silius Italicus, 

 in the time of Nero, fays, " Vefuvius, by its fires, had for- 

 merly caufed great ravages both on the land and at fea." 



The firft great eruption on authentic record took place 

 in the reign of Titus, on the 24th of Auguft, A.D. 79 ; and 

 on the fame the towns of Herculaneum, Pompeii, and Stabiae 

 were buried under (howers of volcanic fand, ftones, and 

 fcoriae. Such was the immenfe quantity of volcanic fand 

 (called afhes) thrown out during this eruption, that the 

 whole country was involved in pitchy darknefs ; and accord- 

 ing to Dion, the afhes fell in Egypt, Syria, and various 

 parts of Afia IMinor. The particulars of this eruption are 

 defcribed in a letter from the younger Pliny to Tacitus : his 

 uncle, the elder Pliny the naturalift, loft his fife by this event. 

 He had the command of the Roman fleet on the coaft of 

 Campania, and wifliing to fuccour thofe perfons who might 

 defire to efcape by fea, and alfo to obferve this grand phe- 

 nomenon more nearly, he left the cape of Mifenura, and 

 approached the fide of the bay nearefl to Vefuvius. He 

 landed and advanced towards it, but was involved in whirl- 

 winds of fulphureous vapour, in which he expired. 



After this period, Vefuvius continued a burning mountain 

 for nearly a thoufand years, having eruptions of lava at in- 

 tervals. The fire then appeared to become entirely extindl, 

 and continued fo from the beginning of the 12th century to 

 the beginning of the i6th, a period of about 400 years. 

 Woods were growing on the fides of the crater, and pools 

 of water were collefted in its centre. Since the eruption 

 of 15C6, it has remained burning to the prefent time, having 

 \'iolent eruptions of lava and aflies at intervals. Thefc 

 have been more frequent during the laft century and the 

 beginning of the prefent, than at any former period. Of 

 twenty-nine eruptions which took place from the time of 

 Titus to 1800, fourteen occurred in the laft century: fcveral 

 have taken place fince the commencement of the prefent 

 century, and the volcano is at this time ( 1817) in a Itatc of 

 aftivity. 



The eruptions of Vefuvius are always preceded by earth- 

 quakes more or lefs violent and cxtenfive, and by a fuccelTion 

 of fubterranean explofions, growing louder before the floncs 

 or lava are ejedled. SirWiUiam Hamilton, the EngUfli am- 

 baflador to the court of Naples from the year 1766 to the 

 latter end of the century, has given fcveral intereiUng dc- 

 fcriptions of the eruptions that took place under his own 

 obfcrvation, which are publiflied in the Tranfaftions of the 

 Royal Society. From 1 769 to 1779 tliere were nine erup- 

 tions, many of tliem confiderable. Moft of the eruptions 

 of Vefuvius take place from the crater at the fummit, but 

 the eruption of 1794, which dcllroycd Torre del Greco, a 

 city containing 10,000 inhabitants, flowed from a large 

 opening made near the bottom of the cone. 



The volcanic produfts of Vefuvius differ confiderably 

 from thofe of jEtna, and ftill more from thofe of the volca- 

 noes in the Lipari iflands, more immediately in its vicinity. 

 White pumice and obfidian, a volcanic glafe, have not been 

 R found 



