Volcanoes: What They are and What They Teach

by John W. Judd

ABICH, cited, [122]
— researches of, [4]
Absorption of gases by liquids and solids, [354], [355]
Acid lavas, [48]
Æolian Islands. See [Lipari Islands]
Æolus, origin of myth, [35]
Africa, volcanoes of, [227]
— South, diamonds of, [147]
Agates, formation of, [150]
Allport, Mr., cited, [259]
Alps, formation of, [292]
Altered lavas, names given to, [261]
America, volcanoes of, [227]
Amygdaloids, formation of, [140], [141]
Andesites, [50], [59]
Andesite-volcanoes, [126]
Andrews, Professor, cited, [321]
Anne Boleyn and Etna, [3]
Armstrong, Sir W., hydro-electric machine, [29]
Arthur's Seat, [275]
Artificial stone, [55]
Asia, volcanoes of, [227]
Asiderites, [316]
Asmanite, [314]
Astroni, crater-ring of, [170]
Atlantic, volcanoes in, [223]
Auvergne, breached cones of, [123], [fig. 40]
— denuded cones in, [124], [fig. 42]
— incrusting springs of, [184]
— puys of, [152], [212]
— volcanic cones in, [79]
BALL-AND-SOCKET structure in basaltic columns, [107]
Barrancos, formation of, [209]
Basalt, controversy concerning origin of, [249]
Basalts, [49], [50], [59]
Basaltic columns of Bohemia, [107]
— — of Central Germany, [107]
— — of Monte Albano, [107]
— — from the Giant's Causeway, [107], [fig. 29]
Basic lavas, [48]
Bath, hot spring of, [219]
Ben Nevis, [274]
Bohemia, volcanoes of, [126]
— lavas of, [103]
Boiling. See [Ebullition]
Bonney, Professor, cited, [69], [109], [259]
Boracic acid at volcanic vents, [216]
Bourbon, volcano of, [176], figs. [74], [75]
Bracciano, crater-lake of, [178], [fig. 77]
Breached cones, [123], [fig. 40]
Babbles of steam, escape from lava, [21]
Bubbles, spontaneous movement of, in liquid cavities, [62], [fig. 8]
— — cause of, [65]
Buch, Von, researches of, [4]
Buda-Pesth, deep well of, [335], [341]
Büdos Hegy, Transylvania, [215]
Bunsen, cited, [201]
Burning, does not take place at volcanoes, [2]
CADER IDRIS, [274]
'Calderas,' formation of, [180]
Caldera of Palma, [209]
Cambro-Silurian volcanoes of British Islands, [274]
Campi-Phlegræi, map of, [fig. 11]
— — volcanoes of, [79]
— — tuff-cones of, [118]
— — fissures in, [197]
Carbonic acid in cavities of crystals, [63]
Carboniferous volcanoes of British Islands, [275]
Carlsbad, Strudel of, [218]
— Strudelstein of, [184]
Caspian Sea, mud-volcanoes of, [182]
Catacecaumene, volcano cones in, [79]
Cause of proximity of volcanoes to sea, [239]
Central Asia, volcanoes of, [236]
— America, mud-volcanoes, [182]
— Pacific, volcanoes of, [236]
'Challenger,' H.M.S., voyage of, [73]
— — soundings of, [359]
Chance, Messrs., of Birmingham, [55]
Charnwood Forest, ancient volcanic rocks of, [259]
Chemical deposits at Vulcano, [44]
— — on surfaces of lavas, [110]
— elements present in lavas, [46]
— theory of volcanoes, [344], [346]
Chiaja di Luna, [108]
Chimborazo, size of, [44]
— [151]
Chodi-Berg, Hungary, [161]
Citlaltepetl, view of, [169], [fig. 69]
Coast-lines, proximity of volcanoes to, [228]
Cole, Mr. Grenville, [110]
Colours of lavas, [49]
Columns in lava, [105]
— — dimensions of, [105]
— radiating in intrusive masses, [136]
Columnar structure in lavas, [104]
— — origin of, [105]
Columnar lava-stream on the Ardèche, [107], [fig. 28]
Combustion, does not take place at volcanoes, [2]
Composite cones, [128], [161]
Comstock mines, temperature of, [342]
Concentric jointing in lava, [108], [fig. 30]
Cones composed of viscid lava, [129], [fig. 43]
— miniature on lava-streams, [100], [101], figs. [25], [26]
— natural sections of, [129]
— shifting of axis in, [167]
Coolin Hills, Skye, [144]
Cotopaxi, volcanic dust of, [69]
— view of, [168], [fig. 68]
Craters, formation of, [82]
— origin of, [167]
— position of, [167]
— fissuring of sides, [180]
Crater of Stromboli, aperture at bottom of, [15]
Crater-lakes, formation of, [171]
— of Agnano, [171]
— of Albano, [171]
— of Avernus, [171]
— of Bagno, [171], [fig. 71]
— of Bolsena, [171]
— of Bracciano, [171]
— of Frascati, [173], [175]
— of Gustavila, [171], [fig. 72]
— of Laach, [171]
— of Nemi, [171]
Crater-rings, formation of, [170]
Crater-ring of Somma, [177], [fig. 76]
Crater-ring of Pianura, [174]
— — of Piano di Quarto, [174]
— — of Vallariccia, [174]
Creuzot, shafts at, [340]
'Critical point' of liquids, [63]
Crust of globe, definition of, [308]
Crystals in lavas, [51]
— — formed of crystallites, [54-57]
— — formed in subterranean reservoirs, [60]
— — interruption in growth of, [60]
— pressure under which formed, [65]
— deposited on surface of lava, [110]
— porphyritic, origin of, [256]
Crystalline minerals formed beneath volcanoes, [146], [147]
— — ejected from volcanoes, [147]
Crystallised minerals of volcanoes, [46]
Crystallites, aggregates of, [54], Frontispiece
Crystallites in lavas, [53], Frontispiece
Crypto-crystalline base, [57]
'Cupolas,' [135]
Corral of Madeira, [209]
DACITES, [198]
Dana, Professor, J. D., cited, [100], [159], [291], [301], [327], [338], [339]
Darwin, Mr., cited, [245], [246], [271], [289]
Daubeny, cited, [182]
Daubrée, M., cited, [147], [315], [320], [358]
Daubréelite, [314]
Davy, Sir Humphry, chemical theory of volcanoes, [344], [345]
Deccan of India, [103]
Density of the earth, [306]
Denuded cones and craters, [158], [fig. 59]
Denudation, effects of, on volcanoes, [114]
Deposits about volcanic fissures, [42]
Detonations at Vesuvius, [26]
Devonian volcanoes of British Islands, [274]
Diorite, [59]
Dolomieu, cited, [4], [39]
Durocher, cited, [201]
Dykes, formation of, [116], [117], [209], [210]
— structure of rock in, [211]
— pseudo-, [119]
Dynamical theory of volcanoes, [347], [348]
EARTH'S interior, nature of, [309]
— — physical condition of, [325]
— — hypothesis concerning, [328-330]
— relation to other planets, [310], [311]
Earthquakes, depth of origin of, [343], [344]
— connection with volcanoes, [343]
— accompanying Vesuvian eruption of 1872, [27]
Ebullition, compared to volcanic eruptions, [19], [20]
Eifel, volcanic cones of, [45]
Ejected blocks, [45]
— materials, height to which thrown, [72]
— — stratification of, [117-119]
Elements, pyroxenic and trachytic, theory of, [201]
Elevation-craters, theory of, [135], [200]
Erroneous opinions, sources of, in regard to volcanoes, [2]
Eruptions, feeble and violent compared, [31]
— prediction of, not possible, [32]
— intervals between, [33]
— of varying intensity, [33]
— and barometric pressure, [36]
— effects of repetition of from same fissure, [80]
Eruptive action in sun and moon, [360-369]
Etna, ideas of ancients concerning, [3]
— and Anne Boleyn, [3]
— observatory on, [37]
— size of, [44]
—, [151]
— eruptions at summit and on flanks, [207]
Etna, dyke and lava-stream in, [133], [fig. 54]
Etna, views of, [162], [163], figs. [62], [63]
Euganean Hills, [139]
— — volcanoes of, [201]
Europe, volcanoes of, [227]
Extra-terrestrial rocks, [316]
Extra-terrestrial rocks, relation to ultra-basic rocks, [322], [fig. 88]
FELSTONES, [263]
Ferric-chloride, mistaken for sulphur, [41]
Fissure on flanks of Etna, [194], [fig. 84]
Fissure-eruptions, [188]
Fissures, volcanic cones on, [194]
— systems of, [198]
Fingal's Cave, [106]
Flames, phenomena mistaken for, [2]
— at volcanoes, feebly luminous, [17]
— false appearance of, in volcanoes, [17]
Flames at volcanic vents, [41]
Flashing lighthouse, compared to Stromboli, [10]
Floods, accompanying volcanic outbursts, [30]
Forbes, Mr. David, cited, [337], [339]
Fossils, from beneath Vesuvius, [45]
— supposed in basalt, [250]
Fouqué, M., cited, [110], [213]
Fumaroles, gases emitted from, [213]
Fusiyama, form of, [90], [166]
Fusiyama, [178], [fig. 77]
GABBRO, [59]
Gardiner's river, travertine terraces of, [185]
Gases emitted from volcanoes, [40]
— — volcanic vents, [212-216]
Geanticlinals, formation of, [297]
Gems, formation of, [147]
— mode of occurrence, [148]
Geological continuity, doctrine of, [247]
Geosynclinals, formation of, [294]
Geysers, formation of, [217]
— intermittent action of, [218]
— of Colorado, [184], [217]
— of Iceland, [184], [217]
Giant's Causeway, [108]
Gilbert, Mr. G. K., cited, [208]
Girgenti, mud-volcanoes of, [182]
Glass, formed by fusion of lavas, [52]
Glasses, composed of certain silicates, [58]
Glassy base, [57]
Goethe, cited, [112]
Graham Isle, [178], [179], [fig. 78]
Graham, cited, [345]
Grand Sarcoui, Auvergne, [161]
Granite, [59]
Granite of Secondary and Tertiary ages, [254]
Granitic rocks, position beneath volcanoes, [145]
Great earth movements, nature of, [286]
Great volcanic bands of the globe, [232-234]
Grenelle, boring of, [341]
Greystones, [49]
Groundmass of lavas, [52]
Grotto del Cane, [215]
Guevo Upas, Java, [215]
Guiscardi, Professor, referred to, [45]
Gustavila, crater-lake of, [172], [fig. 72]
HAMILTON, Sir W., researches of, [4], [75], [84]
— — observations on Vesuvius, [80]
Hannay, Mr., referred to, [147]
Hartley, Mr. Noel, referred to, [65]
Hawaii, volcanoes of, [100], [125]
— — lava-masses of, [159]
— — volcanic eruptions at different levels, [327]
Hebrides, volcanoes of, [271]
Henry, Dr., cited, [355]
Henry Mountains, Southern Utah, [208]
Hephæstus, forge of, [3]
Hochstetter, cited, [135], [356]
Holosiderites, [315]
Hopkins, Mr., cited, [349]
Hot springs, numbers of, [219]
Humboldt, researches of, [4]
Hungary, lavas of, [96], [103]
— volcanoes of, [126], [201]
— deep wells of, [341]
Hverfjall, Iceland, [178], [fig. 77]
Hydro-electric machine of Sir W. Armstrong, [29]
Hypothesis, value of, [331-333]
ICE under lava of Vesuvius in 1872, and of Etna, [110]
Iceland, volcanic dust of, carried to Norway, [72]
Indian Ocean, volcanoes in, [229]
Insel Ferdinandez, [178], [179], [fig. 78]
Intermediate lavas, [48]
Intervals between Eruptions, [33]
Ireland, north-east of, [103]
Iron in Ovifak-basalts, [319], [fig. 87]
Iron, seething of, [356]
— of Ovifak, terrestrial origin of, [320]
Ischia, eruption in 1301, [164]
— crater-lake of Bagno in, [172], [fig. 71]
— plan of, [163], [fig. 64]
— parasitic cones in, [164], [fig. 65]
Island of Bourbon, [93]
Isle Julie, [178], [179], [fig. 78]
Isogeotherms, [359]
JANSSEN, referred to, [42]
Joint-structures in lava, [104-110]
KAMMERBÜHL, [112-114], [fig. 33]
— section of, [114], [fig. 34]
— section in side of, [118], [fig. 36]
Kant, nebular hypothesis of, [352]
Kilauea, volcano of, [71], [138]
— crater of, [181]
King, Mr. Clarence, cited, [301]
LAACHER SEE, minerals ejected at, [149]
Lac Paven, Auvergne, [171], [fig. 70]
'Laccolites,' formation of, [208]
Lago di Bolsena, [173], [175]
Lago di Bracciano, dimensions of, [172], [173]
Lake Avernus, [215]
Lapilli, [70]
Laplace, nebular hypothesis of, [325], [352]
Lavas, action of acid gases on, [41]
— resemblance to slags, [46]
— chemical elements in, [46]
— oxygen in, [47]
— silicon in, [47]
— proportion of silica and other oxides in, [47]
— silicates in, [47]
— acid, intermediate, basic, [48]
— specific gravities of, [49]
— colours of, [49]
— microscopic study of, [50]
— fusibility of, [51]
— minerals in, [51]
— artificially fused, [51]
— crystals in, [51], [93]
— ground mass of, [52]
— crystalline forms of, [59]
— of Bohemia, [103]
— of Hungary, [96], [103]
— of Kilauea, [95]
— of Lipari, [96]
— of Niedermendig, [103]
— of Vesuvius, [104]
— of Volvic, [95]
— of Volcano, [95]
— presence of water In, [102]
— chemical deposits on, [110]
— different fluidity of, [204]
— augite and hornblende in, [267]
Lava, cascade of, [93], [fig. 18]
Lava-cones, composed of liquid lava, [125]
— — of viscid lava, [126], [127]
— characters of, of liquid lava, [159]
— — of viscid lava, [160]
Lava-cones, outlines of, [160], [fig. 60]
Lava, in deep-seated reservoirs, [138]
— consolidation of, at great depths, [139]
Lava-fountains, [94]
Lava-sheets, intrusive, [136], [137], [fig. 56]
'Lava' ornaments of Naples, [45]
'Lava,' slow-cooling of, [110]
— a bad conductor of heat, [110]
— ice under, [110]
Lava-streams, nature of movements, [92]
— difference in liquidity of, [92]
— miniature cones on, [100], [101]
— vast dimensions of, [102]
— structure of, [103]
— position of columns in, [106]
— sinking of surface of,

[111]
'Lave di fango,' [30]
'Lave di fuoco,' [30]
Lawrencite, [314]
Laws of volcanic action, [38]
Le Conte, cited, [347]
Leucite, absence from ancient lavas, [268]
Lightning, accompanying volcanic outbursts, [28]
Linear arrangement of volcanic vents, [191]
— — of volcanoes, [231]
Lipari Islands, [3], [39]
— — fissures in, [197]
— — pumice-cones in, [154]
— — order of appearance of lavas in, [200]
— — breached pumice-cones in, [124], [fig. 41]
— — map of, [192], [fig. 81]
— — lavas of, [96], figs. [20], [21]
Liquids in cavities of crystals, [63]
Liquid cavities in lavas, [60], [fig. 7]
— — spontaneous movement of bubbles in, [62], [fig. 8]
— — spontaneous movement of bubbles in, cause of, [65]
Lockyer, Mr. Norman, cited, [322], [363], [364]
Lunar craters, [368], [fig. 95]
Lyell, Sir Charles, cited, [135], [167], [197]
MACCULLOCH, cited, [207], [208]
Madeira, cliff-section in, [128], [fig. 47]
Magmas, theory of, [201]
— objections to, [202], [203]
Mallet, Mr., cited, [269], [343], [346]
Mamelons of Bourbon, [126], [127], figs. [45], [46]
Maskelyne, Professor, cited, [314]
Massa di Somma, destruction of, [26]
Mauna Loa, [138]
Metamorphism around volcanic vents, [145]
Meteorites, nature of, [312]
— composition of, [313]
— minerals of, [314]
— classification of, [315]
Melaphyres, [262]
Miascite, [59]
Michel Lévy, M., [110]
Micro-crystalline base, [58]
Microliths. See [Crystallites]
Microscopic study of lavas, [50]
Minerals in lavas, [51]
— of Vesuvius, [46]
Mineral-veins, formation of, [149]
— connection with volcanoes, [220]
— nature of materials in, [321]
Misenum, Cape of, section of tuff-cone of, [121], [fig. 38]
Modena, mud-volcanoes of, [182]
Mont Dore, section at, [130], [fig. 48]
Monte Cerboli, Tuscany, [216]
Monte Massi, Tuscany, well at, [341]
Monte Nuovo, history of formation of, [76]
— — description of, [77], [78], [fig. 10]
— — [152]
— — crater of, [168]
— — production of fissure at, [190]
Monte Rotondo, Tuscany, [216]
Moon, effect of internal forces on, [305]
Mountains, all volcanoes not, [2]
Mountain-chains, formation of, [291]
— — all of recent date, [292]
Mud-streams at volcanoes, [30]
Mud-volcanoes, formation of, [181], [182]
Mull, dissected volcano of, [142-4], figs. [57], [58]
Muscovite, absence of, from modern lavas, [268]
NEBULAR hypothesis of Laplace, [325], [352]
— — of Kant, [352]
New Zealand, geysers of, [217]
— — volcanoes of, [135]
— — volcanic cones in, [79]
Niedermendig, lava of, [103]
Nordenskiöld, Professor, cited, [318]
OBSERVATORY on Vesuvius, [24], [37]
— on Etna, [37]
Obsidian, [59]
Oceans, depth of, in volcanic areas, [242]
Oceanic islands, volcanoes in, [228]
Oliver, Capt. S. P., [92]
Oldhamite, [314]
Outlines of Vesuvius, [87], [fig. 17]
Ovifak, iron-masses of, [319]
Oxidation of materials of globe, [324]
Oxygen, proportion in lavas, [47]
PACIFIC, volcanoes in, [229]
Palmieri, Professor, cited, [25], [37]
Papandayang, eruption of, [169]
Papin's digester, nature of action in, [22]
Parasitic cones, formation of, [161], [162], [fig. 61]
Pele's Hair, [71]
Perlitic structure, [109]
Phillips, Mr. J. A., cited, [220]
Phonolites, [50], [59]
Phonolite-volcanoes, [126]
Photograph of Vesuvius eruption, [24], [fig. 5]
'Pine-tree, appendage of Vesuvius, [29]
Pitchstones, porphyritic, [60]
Plateaux formed of lava-sheets, [270]
Pliny, Elder, death of, [7]
Plombières, hot springs of, [147]
Plutonic rocks, [61]
Pompeii, nature of materials covering, [117]
Ponza Islands, [39]
Ponza, sections in, [131], [132], figs. [51], [52]
Porphyrites, [263]
Porphyritic pitchstones, [60]
Potentially liquid rock, [250]
Pre-Cambrian volcanoes of British Islands, [274]
Presence of water in lavas, [353]
Pressure under which crystals were formed, [65]
Predazzo, ancient volcano of, [165], [fig. 67]
Propylites, [199]
Pseudo-dykes, [119]
Pumice, how formed, [68]
— cause of white colour of, [71]
— floating on ocean, [73]
— on ocean-beds, [73]
Pumice-cones, [154]
Puy de Pariou, Auvergne, [193], [194], figs. [82], [83]
Puzzolana, [89]
RAIN, accompanying volcanic outbursts, [30]
Rate of movement of lava-streams, [97]
Rath, Professor Vom, [72]
Red clay of ocean-beds, [74]
Red Mountains, Skye, [144]
Reservoirs beneath volcanoes, [145]
Reyer, Dr. Ed., experiments of, [125], [160]
Reykjanes, eruption of, in 1783, [102]
Rhyolites, [50], [59]
Richthofen, Von, cited, [196], [199], [200], [205]
Rocca-Monfina, [178], [fig. 77]
— —, [204]
Rock-masses, movements of, [288]
Rocky Mountains, [103]
— — volcanoes of, [201]
Rotomahana, sinter-terraces of, [185]
Ropy-lavas, [98], [fig. 24]
SALINA, section in, [132], [fig. 53]
Sandwich Islands, lavas of, [125]
San Sebastiano, destruction of, [26]
San Stephano, section in, [131], [fig. 50]
Santorin, [42]
Sarcoui, Grand Puy of, [126], [fig. 44]
Sciarra del fuoco, [13]
Scoria, how formed, [68], [70]
Scoria-cones, altered by acid gas, [155]
— breached, [156]
— characters of, [153]
— preservation of, [155]
— red colour of, [154]
Scoria-cone in Vesuvius, [122], [fig. 39]
Scoria-cone near Auckland, N. Z., [165], [fig. 66]
Schmidt, referred to, [153]
Schreibersite, [314]
Scrope, Mr. Poulett, cited, [5], [69], [106], [135], [198], [205], [212], [238], [289]
Sea of Azof, mud-volcanoes of, [182]
Secchi, Father, cited, [362]
Shiant Isles, [105]
Silica, presence in lavas, [47]
Silicates in lavas, [47]
Silicon, proportion in lavas, [47]
Siliceous sinter, deposits of, [220]
Silver, spitting of, [355]
Silvestri, Professor, cited, [230]
Similarity of lavas of different ages, [260]
Sinter-cones, forms of, [183], [fig. 79]
Skye, dissected volcano of, [144]
Slags, compared with lavas, [46]
Smith, Lawrence, cited, [320]
Smoke, appearance of, due to steam, [2]
Snowdon, [274]
Solar prominences, [364-366], figs. [92], [93], [94]
Solfatara of Naples, [214]
Solfatara-stage of volcanoes, [215]
Somma, [133]
— crater-ring of, [83]
Sorby, Mr. H. C., referred to, [59], [252]
Spallanzani, early researches of, [4]
— observations on Stromboli, [8]
— cited, [39], [367]
Specific gravities of lavas, [49]
— — of glassy and crystalline rocks, [59]
Spectroscope in vulcanology, [41]
Spectrum-analysis, results of, [311]
Specular-iron, deposited on lava-streams, [110]
Sperenberg, boring of, [341]
Sphærulites, [54], Frontispiece
Sporadosiderites, [316]
Stability of crust of globe, [326]
Staffa, Isle of, [106]
Steenstrup, cited, [319]
Steam-engine compared to volcano, [8]
Steam, emitted by lava of Vesuvius, [27]
Sternberg, referred to, [113]
St. Kilda, [181]
Stokes, Professor, [65]
St. Paul, Island of, [180]
Stromboli, [42], [158]
— apertures at bottom of crater, [15]
— appearances in crater of, [16]
— — at night, [10]
— compared with Vesuvius, [23]
— crater of, [13]
— dependence of eruptions on atmospheric conditions, [34]
— eruption of, [14], [fig. 4]
— general features of, [11]
— map of, [11], [fig. 2]
— observations by Spallanzani, [8]
— resemblance to flashing light, [10]
— section of, [13], [fig. 8]
— soundings around, [12]
— vapour-cloud above, [9]
— violent eruptions of, [23]
Strombolian stage, [23]
Stufas, nature of, [217]
Submarine volcanoes, [179]
Subterranean forces, beneficial effects of, [303]
Subsidence in centre of volcanoes, [165]
Sulphur, absorption of water by molten, [356]
— deposited on lava-streams, [110]
— how formed at volcanoes, [18]
— not the cause of volcanic outbursts, [18]
Surfaces of lava-streams, [97-99], figs. [22], [23]
Sun-spots, [361-363], figs. [89], [90], [91]
Syenite, [59]
Syssiderites, [316]
Szabo, Professor, cited, [199]
TACHYLYTE, [59]
Tertiary volcanoes of British Islands, [276]
Terraces, sinter- and travertine-formation of, [185], [fig. 80]
Temperature, increase in deeper parts of earth's crust, [335]
— rate of increase in different areas, [340]
Teneriffe, [44], [151]
Teneriffe, [178], [fig. 77]
— peak of, [175], [fig. 73]
Tenon-and-mortise structure in basaltic columns, [107]
Theodosius and Vulcano, [3]
Thunder, accompanying volcanic outbursts, [28]
Trachytes, [49], [50], [69]
Trap-rocks, origin of, [241]
Trass, [90]
Travertine or Tibur-stone, [184]
— deposits of, [220]
Triassic volcanoes of British Islands, [275]
Tridymite deposited on lava-streams, [110]
Troilite, [314]
Troost, cited, [355]
Tufa, or tuff, [90]
Tuff-cones, character of, [157]
— denudation of, [157], [158]
Typhon, fable of, [3]
ULTRA-BASIC lavas, [50], [66]
— rocks, [317]
VAL DEL BOVE, Etna, [133], [180], [209]
— — dykes in, [134], [fig. 55]
Vapour-cloud over Vesuvius, [26], [29]
— — Stromboli, [9]
Ventotienne, Island of, section at, [130], [fig. 49]
Vesuvius, [37]
— changes in form of, [81]
— compared with Stromboli, [23]
— crater of in 1756, [84], [fig. 14]
— — of in 1767, [85], [fig. 16]
— — of in 1822, [82], [fig. 13]
— — of in 1843, [86], [fig. 16]
— detonations at, [26]
— early history of, [83]
— eruption of year 79, [84]
— — of 1822, [69]
— — of April 1872, [24]
— — of October 1822, [24]
— ejected blocks of, [45]
— first eruption of, [7]
— form of, [166]
— fossils of, [45]
— growth of cone of, [80]
— history of, [204]
— last eruption of, [7]
— lava-stream of 1855, [101]
— lava-streams of 1858, 1872, [97]
— lavas of, [104]
— minerals of, [46]
— — ejected at, [149]
— observatory on, [24], [37]
— outlines of, [87]
— pine-tree appendage of, [29]
— scoria-cones in lava, [122]
— — on lava of 1855, [153]
— steam emitted by lava of, [27]
— vapour-cloud over, [26], [29]
Vesuvian stage, [23]
— eruption, photograph of, [24], [fig. 5]
Viscid lavas of Lipari Islands, [94-96]
Vitreous lavas, devitrification of, [259]
Volcanic action, laws of, [32]
— bombs, [70], [71]
— cycles, nature of, [221], [222]
— — duration of, [223]
— cones, internal structure of, [115-122]
— — experimental illustration of formation of, [120], [fig. 37]
— — limits to height of, [166]
— — form of, [152]
— — dimensions of, [152]
— — irregular development of, [90]
— — slopes of sides of, [91]
— — composed of ejected rock-fragments, [156]
— — curved slopes of, [156]
— débris on sea-bottom, [240]
— dust, fineness of, [69]
— districts, areas of upheaval, [245]
— ejections, alteration of, [258]
— eruptions, compared to ebullition, [19], [20]
— forces, compensate for denudation, [283]
— — intensity at former periods, [278]
— — necessity for action of, [285]
— — shifting of from one area to another, [277]
— mountains, origin of conical forms, [89]
— — mode of growth, [89]
— phenomena of the past similar to those at present, [273]
— products, order of appearance of, [198], [199]
Volcanic rocks, [61]
— — similarity of ancient and modern, [253]
Volcano, origin of name, [3]
— craters of, [167]
— Island of. See [Vulcano].
— compared to steam-engine, [8]
Volcanoes, blocks, ejected from, [45]
— built up of ejected fragments, [74]
— destruction caused by, [281]
— dissected by denudation, [115], [139]
— erroneous ideas concerning, [1]
— ejection of different materials from, [205]
— known to ancients, [3]
— life-history of, [186]
— number of, [224], [225]
— of Africa, [227]
— of America, [236]
— of Asia, [236]
— of Bohemia, [126]
— of Central Asia, [236]
— of Central Pacific, [236]
— of Europe, [227]
— of Hungary, [126]
— position in relation to mountain chains, [243]
— popular ideas concerning, [1]
— reservoirs beneath, [145]
Volvic lava of, [103]
Vose, cited, [346]
Vulcan, forge of, [3]
Vulcano, island of, [3], [158]
Vulcano and Theodosius, [3]
Vulcano, [178], [fig. 77]
— and Vulcanello, view of, [43], [fig. 6]
— chemical deposits at, [44]
— eruption in 1786, [43]
— — in 1873, [43]
— — lava-stream in, [95], [fig. 19]
— —, [103], [fig. 27]
— plan of, [195],

[fig. 85]
— section of volcanic cone in, [116], [fig. 35]
— section in, [129]
— shifting of centre of eruption in, [196]
Vulcanello, craters of, [197], [fig. 86]
Vulcanology, origin of the science, [4]
— earliest treatise on, [5]
WALFERDIN, M., cited, [340]
Water in lavas, [353]
— penetration through rocks, [358]
— presence of in lavas, [102]
— and saline solutions in cavities of crystals, [63]
Werner, cited, [201]
Western Isles of Scotland, [103], [139], [142]
— — volcanoes of, [212]
Whymper, Mr., [69]
Woodward, Mr., experiments of, [119]
Wrekin, ancient volcanic rocks of, [259]
YOUNG, Professor, cited, [365]
ZEOLITES, formation of, [150]

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