CATALAjV/ MOUNT VESUVIUS. Worfcs b professor AUTHOR OF "MOUNT VESUVIUS." In crown 8vo, cloth extra, price 2s. 6d. GEOLOGY FOR ALL, With Tables of the Principal Rock-forming Minerals, Geological Strata, &c., &c. In foolscap 4/0, tastefully printed and attractively bound in cloth extra, with Map and Illustrations of Local Scenery, &c., price 2s. 6d. HAMPSTEAD HILL, With Chapters on THE FLORA OF HAMPSTEAD, by H. T. Wharton, M.A., M.R.C.S., F.Z.S., &c., THE INSECT FAUNA OF HAMPSTEAD, by Rev. Dr. Walker, F.L.S., F.R.G.S., &c., and THE BIRDS OF HAMPSTEAD, by J. Edmund Harting, F.L.S., &c., &c. LONDON : ROPER AND DROWLEY, n, LUDGATE HILL, E.G. Plate I. MOUNT VESUVIUS. A DESCRIPTIVE, HISTORICAL, AND GEOLOGICAL ACCOUNT OF THE VOLCANO AND ITS SURROUNDINGS. J. LOGAN LOBLEY, F.G.S., &c., PROFESSOR OF PHYSIOGRAPHY AND ASTRONOMY, CITY OF LONDON COLLEGE AUTHOR OF "GEOLOGY FOR ALL," &c. WITH MAPS AND ILLUSTRATIONS. '\Here verdant vines o'erspread Vesuvius' sides, The generous grape here poured her purple tides.' " Now flaming embers spread dire waste around, And gods regret that gods can thus confound." Conbon : ROPER AND DROWLEY, ii, LUDGATE HILL. TO THE FAITHFUL GUARDIAN OF THE HONOUR AND LIBERTIES OF ITALY, AND THE FRIEND OF SCIENCE AND EDUCATION, HIS MAJESTY KING HUMBERT I., THIS ACCOUNT OF THE GREATEST NATURAL WONDER OF THE ITALIAN PENINSULA is, BY HIS MAJESTY'S VERY GRACIOUS PERMISSION, MOST RESPECTFULLY DEDICATED. 627 CONTENTS. PAGE PREFACE I3 CHAPTER I. THE NEAPOLITAN VOLCANIC REGION. Three Principal Italian Volcanic Regions The Neapolitan Volcanic Region The Phlegraean Fields The Sol- fatara Extinct Craters Monte Nuovo Temple of Serapis Tufa Hills Stuffe and Thermae Procida Nisida Ischia 17 CHAPTER II. THE SURROUNDINGS OF VESUVIUS. Characteristics Populousness Naples Destroyed Towns Ring of Towns Bay of Naples Appearance from Naples View of Surroundings from the Mountain ... 47 CHAPTER III. THE MOUNTAIN. Name Form Both Typical and Peculiar Five Parts The Lower Cultivated Slopes The Desert Platform The Ridge of Monte Somma The Great Cone The Crater 67 CHAPTER IV. HISTORY TO 1850. Numerous Records The Pre-Historic Volcano Vesuvius Dormant Recognition of Igneous Indications by 8 CONTENTS. PAGE Ancient Writers Renewal of Activity Destruction of Pompeii Formation of the Cone Mediaeval Eruptions Eruption of 1631 -Eruptions of Modern Times 94 CHAPTER V. HISTORY: 1851-1868. Eruptions of 1855 and 1861 Eruption of 1867-68 Aspect of the Surface of Vesuvius during the Eruption of 1868 Ascent to the Summit Lava-Flows The Cone The Ring Terrace The Eruptive Cone and Crater The Eruptive Phenomena seen from the Crater Rim 114 CHAPTER VI. HISTORY : 1869-1888. Repose, 1869-71 Eruption of 1872 Repose, 1873-75 Slight Activity of 1876 and 1877 Activity of 1878 and 1879 Increased Activity of 1880 Strombolean Activity, 1881-83 Scale of Vesuvian Activity Slight Activity of 1884-88 Continuous Observation and Record of Phenomena 135 CHAPTER VII. GEOLOGY OF VESUVIUS. Vesuvius Geologically Instructive and Illustrative Three Geological Divisions The Cone : Cause of its Regu- larity j its Structure, Lavas, Minerals Monte Somma : Change of Position of Axis, Formation of Great Crater-Rings, Structure, Dykes, Minerals The Base : Concavity of Volcanic Outlines, Structure Concealed, Hypothetical Origin, Geological Age Theory of Craters of Elevation ... 162 CONTENTS. 9 PAGE CHAPTER VIII. VOLCANIC ACTION. Pre-scientific Opinion Hypotheses of the Eighteenth Century Later Theories Central Heat Hypothesis of Fused Interior of the Earth with Thin Crust- Recent Hypotheses All Unsatisfactory Compen- dium of the Controlling Facts of Vulcanology Present Favourable Position of the Question for Settlement Author's Conclusions and Hypothesis ... 187 CHAPTER IX. VOLCANIC PRODUCTS. Vesuvian Products largely representative Similarity and Dissimilarity of Volcanic Products Descriptive Cata- logue of Volcanic Products Ejected Blocks with List of Fossils 217 CHAPTER X. THE MINERALS OF VESUVIUS. The Vesuvian Mountain the Richest Mineral Area This Fact Important in Vulcanology Introduction to Catalogue Descriptive Catalogue of Vesuvian Minerals Index of Synonyms and Included Varieties 253 CHAPTER XL THE FLORA OF VESUVIUS. The Flora of Vesuvius and Capri compared Cause of Difference Vesuvian Flora very varied List of Families and Summary of Species List of Medicinal Plants Genera of Graminaceae, Musci, Hepaticse, and Lichens List of Species, with Habitats, of Ferns and Fungi 343 IO CONTENTS. APPENDIX. PAGE LETTERS OF PLINY THE YOUNGER, containing an Account of the Eruption of A.D. 79 ... 355 THE FORMATION OF MONTE Nuovo IN 1538 : Four Con- temporary Narratives I. By Marco Antonio delli Falconi ; II. By Pietro Giacomo di Toledo ; III. By Francesco del Nero; IV. By Simone Porzio 362 CATALOGUE OF RECORDED ERUPTIONS ... 378 THE STRATA UNDERLYING VESUVIUS. Artesian Well Section (Pozzo dell' Arenaccia) ... ... ... 379 PROFESSOR PALMIERI'S SEISMOGRAPH 380 LIST OF ILLUSTRATIONS. PLATE P p"age e I. GENERAL VIEW OF MOUNT VESUVIUS FROM NAPLES (Frontispiece). II. MAP. Mount Vesuvius and its surroundings ... 17 III. MAP. The Neapolitan Volcanic Region ... 25 IV. VIEW OVER THE BAY FROM NEAR POZZUOLI (Hamilton), showing the City of Pozzuoli, the Bridge of Caligula, the Serapeum, Monte Nuovo, Baiae, Misenum, Procida, and Ischia 32 V. Fig. i. MONTE Nuovo FROM POZZUOLI. Fig. 2. PROMONTORY OF MISENUM (Scrope), showing volcanic structure. Fig. 3. THE PHLEGR^AN FIELDS 48 VI. RUINS OF THE TEMPLE OF SERAPIS, showing the three remaining pillars, with the bore-holes of Mollusca from i2ft. to 2ift. above the base ... 64 VII. Fig. i. VIEW OF VESUVIUS FROM SORRENTO (Scrope). Fig. 2. VIEW OF VESUVIUS FROM NAPLES. Fig. 3. VIEW OF VESUVIUS FROM NOLA 80 VIII. Fig. i. VESUVIUS IN THE PRE-HISTORIC PERIOD. A single great cone with an elevation of 7,000 ft. Fig. 2. VESUVIUS IN THE CLASSICAL PERIOD. Upper part of the great conical moun- tain blown away, leaving a vast crater ... ... 96 IX. Fig. i. THE CRATER OF VESUVIUS IN 1756 (Hamilton), showing cone in cone. Fig. 2. THE CRATER OF VESUVIUS IN 1805. (Duca dell a Torre in Roth) 106 X. Fig. i. THE CRATER OF VESUVIUS AFTER THE GREAT ERUPTION OF 1822 (Scrope). Crater greatly enlarged and the cone correspondingly lowered. Fig. 2. THE CRATER OF VESUVIUS IN 1828. (Monticelli in Roth) 112 12 PLATE XI. XII. LIST OF ILLUSTRATIONS. XIII. XIV. ^ XV. XVI. XVII. XVIII. XIX. XX. Opposite Page 1856 THE Fig. i. THE CRATER OF VESUVIUS IN (Herrn Bornemann in Roth.) Fig. 2. CRATER OF VESUVIUS IN 1883. (Lavis) ... 114 Fig. i. VESUVIUS AFTER THE GREAT ERUPTION OF 1631. (Carafa in Roth.) Cone lowered to less than the height of the crest of Monte Somma. Fig. 2. VESUVIUS AFTER ERUPTION OF 1868. Cone almost completed by a new summit cone. Volcano at its greatest elevation during Historic Period ... ... ... ... 118 VIEW OF THE GREAT ERUPTION OF 1872 (5 p.m. April 26th). From the first instantaneous photograph ever taken of an eruption. Show- ing the height of the column of smoke (nearly four miles), and an " exterior eruption " ... 144 DIAGRAMMATIC GENERAL SECTION THROUGH VESUVIUS AT THE PRESENT TIME, showing the structure, the substructure, and the successive accumulations ... ... ... ... ... 176 Fig. i. SECTION THROUGH VESUVIUS BEFORE THE ERUPTION OF A.D. 79. Fig. 2. SECTION THROUGH VESUVIUS AFTER THE ERUPTION OF 1631 186 THE LAVA OF 1858, SHOWING THE SURFACE PRODUCED BY THE SOLIDIFICATION OF SLOWLY- FLOWING LAVA. (From a Photograph.) (Judd's Volcanoes) 224 SIMPLE CRYSTALLINE FORMS. Cubic and Dimetric systems 256 SIMPLE CRYSTALLINE FORMS. Trimetric, Mono- clinic, Triclinic, and Hexagonal systems ... 272 CRYSTALLINE FORMS OF VESUVIAN MINERALS ... 288 PROFESSOR PALMIERI'S SEISMOGRAPH 380 PREFACE. SINCE "Mount Vesuvius" was published in 1868, much has been written on the subject of my brief sketch. A few months afterwards, at the beginning of 1869, Prof. John Phillips issued " Vesuvius," a work which, while rich in classic poetry and ancient fable, gave an extended account of the volcano and its surround- ings, as well as a history in considerable detail of its eruptive activity to the end of the preceding year. Since that time Prof. Palmieri, the faithful watchman of Vesuvius, has recorded the phenomena observable by the eye and ear, or appreciable by the seismograph, and has occasionally made public what appeared to him to be worthy of special atten- tion. He has also written an account of the important eruption of 1872, of which an English translation has been published, with a lengthy and valuable " Introductory Sketch " by our late distinguished seismologist, Mr. Mallet. Descriptive letters in Nature, by Mr. Rod well, containing much scientific information, have added considerably to our knowledge of the state of the volcano to the year 1880. More recently there have appeared communications from an English resident in Naples, Dr. Johnston Lavis, who has devoted much time and labour to the study of Vesuvius, and who, as the secretary of the British Association Committee for the investiga- tion of Vesuvian phenomena, has presented several reports on the subject ; and an elaborate paper on the geology of the volcano, by the same gentleman, has been published in the Quarterly Journal of the Geological Society. In addition to these sources of information and occasional letters and telegrams from Naples in the Athenceum and other journals, a very important volume has been published by the Italian Alpine Club, " Lo Spettatore 14 PREFACE. del Vesuvio e del Campi Flegrei," in which is contained Prof. Palmieri's " II Vesuvio e sua Storia," a new list of Vesuvian minerals by the eminent Neapolitan mineralogist, Prof. Archangelo Scacchi, and a record of changes and phenomena from 1882 to 1886, with photographs, by Dr. Johnston Lavis, together with much interesting matter by other authors. Recent excavations and well-borings have also added to our information respecting Mount Vesuvius, and hence a more complete account of the volcano can now be given than at any former period. The present volume has therefore been prepared to give the latest knowledge on the subject, and to bring down the history of the mountain in a connected form through an interesting twenty years of its existence to the present time. All the explanations of the causes of Volcanic Activity and its varied phenomena which have been advanced by previous Authors are admittedly so unsatisfactory, that I recently ventured to submit the new hypothesis given in the Chapter on Volcanic Action. In view of the great names associated with past attempts to solve the question, this Physio-Chemical theory is offered for consideration with great deference, and I trust that the attention given to the subject during more than twenty years may avert the charge of temerity. Included in the Appendix are the four Contemporary Accounts of the formation of Monte Nuovo brought together for the first time; that by Simone Porzio not having before been published in English. In addition to the writers on Vesuvius mentioned above, I am under great obligations to the other authors whose works have been consulted and whose names appear in the body of the work. The Chapter on the Flora of Vesuvius has been revised by Dr. Henry Wharton, M.A., F.Z.S., &c., to whom I am indebted for giving me the benefit of his extensive botanical knowledge. The elevation of points on the mountain are taken from the great contour map of Vesuvius published by the Institute Topo- grafico Militaire of Italy in 1877, a magnificent map on the scale of i to 10,000, and for the convenience of general readers metres have been reduced to English feet. Translations have also been substituted for the original in classical quotations. PREFACE. 15 To make the book sufficiently complete, the original work has been recast and largely extended, and it is therefore hoped that the volume may prove not altogether unacceptable to the increasing number of Vesuvians as well as to ordinary visitors to the marvellously interesting and attractive Neapolitan volcano. J. L. L. CITY OF LONDON COLLEGE, August, 1889. 1 Oh ! land to mem'ry and to freedom dear, Land of the melting lyre and conquering spear, Land of the vine-clad hill, the fragrant grove, Of arts and arms, of Genius and of Love, Hear, fairest Italy." " The leaves scarce rustled in the sighing breeze ; In azure dimples curled the sparkling seas, And, as the golden tide of light they quaff 'd, Campania's sunny meads and vineyards laugh'd, While gleam'd each lichen'd oak and giant pine, On the far sides of swarthy Apennine." " Saw ye how wild, how red, how broad a light Burst on the darkness of that mid-day night, As fierce Vesuvius scatter'd o'er the vale His drifted flames and sheets of burning hail, Shook hell's wan lightnings from his blazing cone, And gilded heaven with meteors not its own ? " MACAULAY'S " POMPEII. I ^W. HH -ft <^Xf < S\) MOUNT VESUVIUS CHAPTER I. THE NEAPOLITAN VOLCANIC REGION. Three Principal Italian Volcanic Regions The Neapolitan Volcanic Region The Phlegraean Fields The Solfatara Extinct Craters Monte Nuovo Temple of Serapis Tufa Hills Stufe and Thermae Procida Nisida Ischia. MOUNT VESUVIUS, the world-famed volcano of Southern Italy, has been for many centuries an object of great interest to the inhabitants of Europe. In -ancient times, the conspicuous position of the mountain in one of the fairest and most frequented portions of the Roman dominions the resort of the most wealthy, most famous, and most noble of the citizens of Rome and the terrible character and dreadful results of the eruption of the year 79, combined to render Vesuvius an object of especial interest and wonder. In modern times, the proximity of the volcano to one of the greatest cities of Europe, the accessibility to travellers, and the many attractions of the classic and romantic coast of Italy, with, especially, the frequency and violence of the eruptions, have 1 8 MOUNT VESUVIUS. fixed the attention of mankind upon the Cam- panian fiery mountain not less earnestly than in the days of old. But although Mount Vesuvius has absorbed so great an amount of attention, it must not be for- gotten that it is but one of a large number of Italian volcanoes, active or extinct, and forms but the most prominent feature of one of the principal volcanic districts of Italy ; for, besides the minor areas of the Euganian and Vicenian Hills, the Ponza Islands, the Rocca Monfina, and Monte Vulture, there are three principal Italian volcanic regions the Roman, the Neapolitan, and the Sicilian, well marked and well separated from each other. The most northern of the three, the Roman, occupies an extensive area between the Apennines and the Mediterranean, and although there is not now in Latium an active volcanic vent, there are very perfect examples of volcanic craters. Not twenty miles from the walls of Rome, the Lago Albano and the Monte Albano, the Lago Nemi, the Arco d'Aricia, and the great, though incomplete, crater-like wall of Monte Artemesia, at the southern side of the Roman Campagna, are well known ; while north of Rome there are the Lago Bracciano, an immense crater-lake of twenty miles circumference, and the still larger Lago Bolsenna ; while the "seven hills" of the Eternal City itself are but accumulations of ejectamenta from the volcanoes of the district. THE NEAPOLITAN VOLCANIC REGION. 19 In the southern volcanic region, the Sicilian, which is partly terrestrial and partly marine, the giant cone of Etna is still in full activity, and with Stromboli, the " lighthouse of the Mediterranean,'* never dormant, Vulcano and Vulcanello not far off, and the extinct craters of the other Lipari Islands, there are abundant evidences of great volcanic activity in the Sicilian Region, both at the present day and in long-past prehistoric times. Intermediate between the Roman and the Sicilian regions is situated the Neapolitan volcanic region, which, like the Sicilian, is an area partly land and partly sea, since it comprises not only the Vesuvian mountain and the Phlegrsean Fields, but also the marine area in which lie the volcanic islands of Ischia, Procida, and Nisida. It includes, therefore, all the Bay of Naples north of a line drawn from Ischia to Castellamare, for only on the south-eastern side of the bay from the last-named town to Capri are evidences of historic or prehistoric volcanic activity absent, though even here there are small deposits of tufa, but evidently not composed of material ejected from any vent on the Sorrento peninsula, a projection from the giant leg of Italy formed by a spur of the Apennines, and chiefly composed of the limestone called from those moun- tains the Apennine limestone. The Neapolitan volcanic region is, like the Roman, and, indeed, like the Sicilian also, on the western side of the main mountain axis of Italy, 20 MOUNT VESUVIUS. but unlike the former, though like the latter, it has still on one side a marine boundary. This fact has some significance on account of the continuing vol- canic activity in the two regions which touch the sea, and the total extinction of the fires of that one which has been separated, though but a little dis- tance, from the waters of the sea by the advance of the coast line. But although throughout the entire district Mount Vesuvius commands most attention from its magnitude, its position, and the remarkable and splendid phenomena displayed during its fre- quently alarming and sometimes destructive activity, yet in some respects the area of the Phlegrsean Fields is more remarkable still. The scene of classic fable and the theme of Roman poets, the land of gods and giants, titans and sibyls, the Campi Phlegraei excited the wonder and charmed the imagination of the ancient world. A land of fire, of smoke, of vaporous exhalations, mephitic and deadly, of deep hollows and cavernous recesses, of scorched rocks and stones, and subterranean passages, it well might be taken for the ruins of an older world, or imagined to be the vestibule of the realms of Pluto, with the inner portal at Avernus. Yet, with all their terrors, the Campi Phlegnei were not wanting in charms and allurements for the luxurious epicures and sybarites of Rome, Neapolis, Baise, and Pompeii, for in the Lucrine THE NEAPOLITAN VOLCANIC REGION. 21 Lake were beds of the choicest oysters, and on fertile volcanic soils and sunny slopes were here produced the ancient banquet wines, and at but a little distance the famous Falernian itself. Here, too, were temples and baths, and looking over the beautiful Bay of Baiae stood patrician villas, while towns and ports made busy the water's edge. The Phlegrsean Fields extend from Naples to the neighbourhood of the site of ancient Cumae, with a breadth of six or seven miles, and, to accept the usually received etymology, were so named because of the fiery phenomena they displayed, from Qtiyvpos, ardent or burning. Those, however, who love to find a Syriac origin for the names of places in a part of Italy early colonised by the Phoenicians, derive the word Phlegraean from the Syriac Phele Geroh, meaning "wonderful strife," an appropriate designation enough for a region that seems as if it had been a battle-field for beings having command of supernatural powers. Strabo, however, thought the neighbourhood was made the scene of the struggle of giants from its exceeding fertility giving rise to battles for its possession. Certain it is it was very early colonised. Cumae, its chief town perhaps the most ancient of all Italian cities flourished long before Rome was founded, and was the greatest centre of civilisation in Southern Italy in the days of the Tarquins, the last of whom died and was buried here. Its glories had even all departed in the imperial days of Rome, 22 MOUNT VESUVIUS. for it was then spoken of as " Vacuse Cumse " and " Quieta Cumse," and Juvenal says of it : " Griev'd though I am an ancient friend to lose, I like the solitary seat he chose ; In quiet Cumse fixing his repose Where far from noisy Rome secure he lives, And one more citizen to Sibyl gives." Dry den's Juvenal, iii., I. It was afterwards fortified, and became the last stronghold of the Gothic Kings of Italy, but now nothing remains of this renowned city but a few ruins. Cumae itself was situated upon a hill of volcanic material, a trachytic tufa, which breaks the mono- tony of the flat coast between Monte di Procida and the mouth of the Vulturno. Between the region of volcanic craters and tufa hills and the Apennines lies the great plain of Capua, the Campanus Ager, all on volcanic mate- rial of abounding fertility, and famed also for its beauty and the goodness of its harbours, and one of the most valuable districts of Italy, constituting much of the province of Campania, which extends along the Tyrrhenian Sea from the Bay of Poli- castro to beyond Gaeta. In the time of Augustus, Campania was joined to Latium, and hence the neighbourhood of Rome is called by the modern term, Campagna di Roma. So rich and fertile was Campania, and so easy and luxurious was the consequent mode of life there in the time of Hannibal, that his subsequent want of military success, resulting in the loss of Italy and the mastership of the world, has been attributed to THE NEAPOLITAN VOLCANIC REGION. 23 the enervating effect of a winter's sojourn on these volcanic soils. This affords a curious and remark- able illustration of the far-reaching consequences of the geological structure of a country. It was by the Battle of Vesuvius, in 340 B.C., that this splendid district, the Campanus Ager, fell into the hands of the Romans. Then Puteoli and Neapolisgrew and flourished, Baiae and Pompeii rose, and Campania soon became the favourite place of retirement and residence for the distinguished and the wealthy of the dominating city on the Tiber. Great roads were constructed, and the Via Appia, the Via Latina, the road from Rome to Rhegium, and the Via Domitiana along the coast from Sinuessa to Neapolis, facilitated access to and through the beautiful region.* The whole area of the Phlegraean Fields appears to be occupied by more or less completely ridge- encircled basins, one still evolving gases, hot fumes, and steam. Some of the wholly or partially circular hollows are enclosed by lofty walls of scoriae and ashes forming incomplete or truncated conical hills, and a few are encircled by inconsiderable worn and wasted ridges at no great height above the sea-level, but all are evidently craters resulting from volcanic action. Looked down upon from above, the district would resemble most of all, to compare small things * The chief towns of Campania were Capua, Cumse, Neapolis, Nola, Baiae, Pompeii, Puteoli, Herculaneum, Vulturnum, Liternum, Teanum, Salernum, Sinuessa, Misenum, Surrentum, Picentia, Venafrum. 24 MOUNT VESUVIUS. with great, a portion of the surface of the moon, which, like that of the Phlegraean Fields, is doubtless also the result of past volcanic activity. One of these craters is not yet indeed altogether extinct. The Solfatara, the " Forum of Vulcan," from a fumarole * still gives forth volcanic fumes which deposit pure sulphur on the intercepting rocks and stones ; and from it the name Solfatara is now generally applied to volcanic openings from whence issue sulphurous fumes. After speaking of Puteoli, Strabo writes : " Immediately above it is Vulcan's assembly-room, a level space surrounded by fiery heights, having numerous chimney-like mouths, which throw out smoke with great noise; and the level interior is full of drifted sulphur." Subterranean hollows furnish evidence of themselves by giving back resounding noises when heavy stones are thrown down upon the old crater floor, but so wide and level is the plain that its cavernous substructure seems to be due rather to fissures or interspaces between large masses than to a great abyss arched over by the present floor of the old crater. All around the low cliffs display degraded crater walls, but yet the Solfatara, as an active volcano, is by no means prehistoric, for there was an eruption here in A.D. 1198, when a stream of lava flowed to the sea and produced the great mass of trachytic rock forming Monte Olibano, "Opo S B^, the barren mountain, and covering the ancient cemetery on the Via Puteolana. This flow of lava was a very consider- Plate III. LOVOOfti aOfEflJi rif>OWl.Y. II, LUDGATE. H/U.E.I THE NEAPOLITAN VOLCANIC REGION. 25 able one, and touched the sea with a front of a quarter of a mile in width and seventy feet in height. The rock, essentially different from the lava rocks of Vesuvius, which are not trachytic, has been extensively quarried for building purposes. Dr. Daubeny says : " The trachytic lava of Monte Olibano, although differing from the rock of the Solfatara itself, agrees with it in being essentially a felspar with augite only occasionally." * The whole mass rests on a thick deposit of scoria and ashes. Pre- vious to the eruption of 1198, which greatly injured Pozzuoli, the volcano appears to have been in very much the same condition as at present. Between the Solfatara and the sea stood the city of Puteoli, which at one time almost extended to the. volcano. Founded by a Greek colony from Cumae, it was named Dicoearchia, but when in possession of the Romans it was by them called Puteoli, and became one of the two ports of Rome, the other being Ostia at the mouth of the Tiber. It was then the chief place of debarkation for travellers to Rome by sea from the south and from the east, from Egypt, Syria, and Greece, and was accordingly the landing- place of St. Paul, who remained at Puteoli seven days. So commodious was the harbour in the time of Augustus, both in space and depth, that the large vessels required for the shipment of the Egyptian obelisks then brought to Rome were well accommodated in its waters. The city has suffered * Daubeny, "Volcanoes," p. 171 (ist ed.). 26 MOUNT VESUVIUS. greatly by war, pestilence, earthquakes, and vol- canoes, but under the name of Pozzuoli it is still a town of upwards of 15,000 inhabitants. The Solfatara may be considered to be a con- necting link between Vesuvius and the quite extinct craters of the Phlegrsean Fields. Of these, Astroni is the largest, having an exterior circumference of about four miles, and a diameter of a mile, but it has so lost its volcanic aspect that it is now a royal preserve for " big game," wild boars and wild deer finding in the underwood of the arena of the amphi- theatre, so to speak, a congenial covert and abode. The bottom of this large crater has in its centre a boss of trachy tic rock without traces of a crateral opening, as if it had been pressed out of the volcanic tube in a plastic state and had remained a mound-like mass until entire solidification had followed. The cir- cular hollow around is covered with oak and ilex, and beneath their shade are three secluded pools of water amidst rich verdure. Monte Barbaro, anciently Mons Gaurus, is not so large a crater, though upwards of three miles in circuit, but it has much more lofty enclosing walls. It is a conspicuous object, displaying a high conical hill, with its steeply rising sides covered with vine- yards. This is the highest of all the cratered cones of the Phlegraean Fields, and is geologically more than ordinarily interesting, on account of an opening through the crater wall on the eastern side which reveals its structure, and clearly shows that the whole THE NEAPOLITAN VOLCANIC REGION. 27 cone has been produced by the fallen fragmentary ejections from the central vent, probably the ejecta- menta of one eruption only, without any flow of lava, no lava-rock being anywhere visible. In the immediate neighbourhood of Astroni and Monte Barbaro are two smaller but similar craters, named Monte Cigliano and Monte Campana. Agnano, nearly three miles in circuit, is a crater much degraded, but holding until 1870 a lake of water, on the grassy banks of which frogs croaked and lizards crawled in great numbers. So worn and irregular are the boundaries of Agnano that it has not the appearance of a crater, but the beds of tufa dipping away from the interior leave no doubt that it is one, though probably much older than its more perfect neighbours. In consequence of unwholesome malarious vapours arising from the lake, though due not to volcanic fumes, but to the soaking of flax, drainage works were commenced in 1865, and com- pleted in 1 870, by the construction of a tunnel through Monte Spina, which formed a conduit for the waters of the lake to the sea. The area of the water surface was 924,020 square metres, and the depth of the lake 40 feet.* The effect of the drainage has doubtless had good sanitary and economic results, but it has removed a beautiful and interesting scenic feature. Facilis decensus Averno is a familiar phrase to every schoolboy, but not only is the way to it pleasant and easy, but Avernus itself is pleasant * Murray's Handbook to Southern Italy. 28 MOUNT VESUVIUS. also. A circular lake of about a mile in circum- ference, surrounded by rocky shores adorned by luxuriant shrubs, and the glassy water reflecting its picturesque surroundings, it presents a by no means uninviting aspect. In early times, however, mephitic exhalations were doubtless given off from its sides, and the large trees which then overhung the lake that fills the old crater favouring the accumulation of such gaseous emanations, the traditions embodied by the classic poets in their verse would have some foundation. " And here th' access a gloomy grove defends ; And here th' innavigable lake extends, O'er whose unhappy waters, void of light, No bird presumes to steer his airy flight ; Such deadly stenches from the depth arise, And steaming sulphur, that infects the skies. From hence the Grecian bards their legends make, And give the name Avernus to the lake."* But now the air is pure, and the aspect of the place cheerful, for there are no noxious gases and no dense overhanging woods to give a gloomy shade. Agrippa cut down the trees, and disregard- ing poets, traditions, and fables, constructed a "ship canal " from the sea to the lake, and thus Avernus was converted to practical purposes and made a secure harbour for Roman galleys. Some ruins of baths, or " thermae," now called the Temple of Apollo, show that, notwithstanding its forbidding reputation, Avernus was resorted to in ancient times for health and pleasure. * Dryden's " JEneid t " book vi., 340. THE NEAPOLITAN VOLCANIC REGION. 29 The way is less easy to the " Cave of the Sibyl," which is far underground, with a chamber having some depth of water the " Bath of the Sibyl" so that a visitor is fain to be content to be carried on the shoulders of a guide. This is part of the old subterranean road from Avernus to the shores of Lucrinus, though containing what was reputed to be the entrance to the realms of Pluto. " Deep was the cave, and downward as it went From the wide mouth, a rocky, rough descent. ***** 'Tis here, in different paths, the way divides The right to Pluto's golden palace lies ; The left to that unhappy region tends Which to the depth of Tartarus descends."* On emerging from this gloomy cavern, with the placid water of Avernus reflecting the bright sun- shine, and a gap in the seaward side of the old crater wall showing the Lucrine Lake and the blue sea beyond, even the most classically minded might well forget that he was near the Cimmerian abodes. Yet here were the reputed underground dwelling- places of those sunless beings whom Ulysses visited when on his famous travels. 11 The gates of hell are open night and day ; Smooth the descent, and easy is the way ; But, to return, and view the cheerful skies In this the task and mighty labour lies."t Exterior to the low broken walls of Avernus on the landward side is the partly encircling larger * Dryden's " ^Eneid," book vi., 338 and 726. t Ibid., 193. 30 MOUNT VESUVIUS. crater of Monte Grillo, affording another instance of an exterior and an interior crater-ring which is so interesting a feature of the Neapolitan volcanic region. On a level with the sea, and just outside Avernus, is the Lucrine Lake, and only separated from the bay of Baise by a mere causeway, fabled to have been first made by Hercules when driving the oxen of Geryon. It was raised and completed in a more prosaic manner by Agrippa. The canal from the sea to Avernus passed through Lucrinus, making a port with an outer and an inner harbour, and sufficiently spacious for the Roman fleet ; but the cutting was filled up, together, doubtless, with a portion of the area of the lake itself, by the erup- tion of the adjacent Monte Nuovo in the year 1538. And this is the remarkable crater near to the Lucrine Lake that is the newest of all in the Phle- graean Fields, for it is the creation of historic nay, of modern times. Monte Nuovo is also close to the sea-shore, and, rising to a height of upwards of 400 feet as a truncated cone, displays a perfect though not quite circular crater, with steeply de- scending sides, nearly as deep as the interior walls are high. The height above sea-level of the summit rim is stated by Professor Phillips to be 440 feet, and the bottom of the interior crater only 19 feet above the same level, thus giving a depth of 421 feet. The greatest diameter of the crater is stated to be a quarter of a mile, but this must be a THE NEAPOLITAN VOLCANIC REGION. 31 mistake, as it cannot be nearly so much. The dimensions of Monte Nuovo are so differently stated that I greatly regret not having myself measured this remarkable hill. Dr. Daubeny says of it: " Monte Nuovo, 413 feet high, and 8,000 feet in circumference ; composed entirely of frag- ments of scoriform matter, or of a compact rock of an ash-grey colour no tufa." And Scrope : " Monte Nuovo, a tuff cone 430 feet high, with a crater 370 feet deep." While Murray states that " Internally the crater is a continuous cavity, free from fissures or dykes, about a quarter of a mile in circumference, 419 feet deep, and the difference between that and the height of the rim, 2 1 feet." Monte Nuovo was produced by the volcanic energy of three days in September, 1538, which opened a new vent at this place on a plain, or " piano," not necessarily quite level, and, ejecting ashes and scoriae, piled up the present hollow trun- cated cone, which appears to be composed entirely of ejected scoriae and ashes, no lava flow or lava rock having been recorded or detected, though red- hot pumice is mentioned. Volcanic activity has not since recurred to alter its height or form, and thus the accumulation of ejectamenta with its regular crater remains very much as it was left by the creating eruption, except that it is now well grown over by the arbutus and other shrubs, both in- side and out, though we are told that till the end of the last century the scoriae was without vegetation. 32 MOUNT VESUVIUS. From amidst the now peaceful and safe seclusion of the abundant covert so formed, an exceedingly fine fox was disturbed by my exploring footsteps. Monte Nuovo is, however, more than a mere in- teresting addition to the wonders around, since, as will be seen subsequently, it strikingly illustrates the method of the formation of volcanic cones generally, and possesses, therefore, great geological illustrative value. The formation of Monte Nuovo was recorded by no less than four eye-witnesses Marco Antonio delli Falconi, Pietro Giacomo di Toledo, Francesco di Nero, and Simone Porzio whose accounts fur- nish an important chapter in the history of the Phlegrsean Fields, as well as a most useful contribu- tion to vulcanology. (See Appendix.) Many earthquakes during the two preceding years presaged the eruption, and no less than twenty shocks were noted on the day of its com- mencement the 28th of September. Condensed volumes of steam, with showers of ashes, produced deluges of mud that greatly injured the town of Pozzuoli, and it was afterwards found that the village of Tripergole, the Villa of Aggripina, and the canal of Agrippa had all been destroyed, while a rise of the coast was doubtless another result. Triper- gole was a much -frequented watering-place for its mineral springs, with a hospital, and with three inns in the principal street. But perhaps even more wonderful and significant Plate IV. Ill ?3: THE NEAPOLITAN VOLCANIC REGION. 33 in the importance of their geological teaching are the remains of the ancient building usually called the Serapeum, or Temple of Serapis, but probably built for a sumptuous bathing establishment, near the western end of Pozzuoli, and close to the sea-shore. These remains consist of three Cipolino marble pillars, perfect in height, and although not connected by a superstructure, almost so in verticality of posi- tion, standing on a base about a foot below the level of the adjacent sea, the water of which percolates through an imperfectly protecting bank, and covers the ancient floor. At about twelve feet above the base, and occupying a zone of about nine feet in breadth, the same on each column, are the bore- holes of rock-boring marine mollusca (Lithodomus lithophaga), such as live abundantly in the adjoining sea, and now excavate their miniature tunnels in the rocks below the water-line. The existence of this zone of the perforations of marine animals would seem to at once conclusively prove that two changes of level to the extent of about twenty feet each had taken place, and as there is evidence of the interior of the temple having been decorated by marbles in the third century by Septimus Severus and Marcus Aurelius, that these changes of level had occurred since the commencement of the Christian Era. In other words, the site of the temple had, since the building was used in the third century, sunk to more than twenty feet, to which height the pillars had been submerged, and that subsequently a 34 MOUNT VESUVIUS. reverse movement had taken place, and the ground had risen twenty feet, uplifting the pillars until their bases were nearly level with the surface of the sea. So it appeared to Breislac, but Dr. Daubeny, agree- ing partly with Goethe and partly with the Canonico Jorio, thought that the Hthodomi borings could best be explained by supposing an eruption of one of the neighbouring craters producing a mass of material that had impounded for a sufficient length of time a quantity of sea-water around the pillars when the sea had risen to an unusual height from seismic action. He considered that had two such great changes of level occurred as has been supposed, the pillars must have been thrown down. Mr. Babbage, Professor James Forbes, and Sir Charles Lyell, however, have pointed out so many indications of change of level to the extent required, and even to thirty feet, in the immediate neighbour- hood of Pozzuoli, both north and south, that no other conclusion than that there has been a sub- sidence and subsequent upheaval can now be come to. Dr. Daubeny's objection is replied to by the gradual and slow alteration of level alone required, and by the fact that buildings have actually descended from one level to another at the time of landslips without even injury to their walls. The three pillars of the Temple of Serapis therefore furnish most valuable evidence of the changes of relative level of sea and land that may occur, even in no very long periods of time, to entirely alter THE NEAPOLITAN VOLCANIC REGION. 35 geographical outline and terrestrial configura- tion. Confirmatory of the above conclusion is the long stretch of low land by the sea-shore of the Bay of Baiae, with a low cliff bounding it on its landward side, called La Starza. This is composed of hori- zontal beds of pumiceous tufa, containing not only recent sea-shells, but fragments of mosaic pave- ments, &c., all indicating a marine formation of historic times. The famous Mole of Pozzuoli, the so-called Bridge of Caligula, too, has some of its piers perforated by lithodomi ten feet above the sea-level. The exemption of the lower portion of the three pillars of the Temple of Serapis from perforations is accounted for by the accumulation around them of the ejectamenta of the eruption of the Solfatara, in 1198, to the height of twelve feet, previous to the submergence which brought the sea-water to twenty- one feet above their bases. From this position they probably began to emerge before the eruption of Monte Nuovo in 1538, since in 1503 Ferdinand and Isabella granted to the city and university of Pozzuoli some land on the shore of the Bay of Baise where "the sea was drying," and in 1511 where "the sea was dried," and after 1538 newly dis- covered ruins were said to have been found on the shore near Pozzuoli. Previous to the formation of Monte Nuovo, the inner cliff between the Punta di Coraglio and the Lucrine Lake was the sea-cliff. 36 MOUNT VESUVIUS. Since 1 780 this part of the coast appears to have again subsided. Observations for sixteen years from 1822 were carefully made and recorded, and the result, as reported by Signor Nicolini, was that the land appeared to have been sinking during that period at the rate of about a quarter of an inch annually. Professor Guiscardi found, from noting the sea-line on the Mole of Pozzuoli, first in 1840, and then twenty-five years afterwards, in 1865, that a change of 0*349 metre had taken place, indicating a land subsidence at the rate of i'396 metres in a century. This giving half an inch annually shows a doubling of the rate of subsidence. The south-eastern boundary of the Phlegrsean Fields is the commanding tufa-formed ridge of Posillipo (iiavafrvTrov, end of care), which separates this lunar-like district from the suburbs of the city of Naples, and overlooks the great bay towards Vesuvius, Sorento, and Capri. Through it runs the famous Grotto of Posillipo, an artificially formed tunnel for the high-road, of the construction of which there is no record. It has been ascribed to those busybodies of the olden times, the fairies, and also, with equal probability, to the magical power of Virgil, whose tomb is on the ridge near the eastern end of the grotto; but possibly it was cut by Marcus Agrippa, about the year 27 B.C. Although the tunnel is a very considerable one, being no less than 2,244 feet long by 21 feet wide, with an entrance 69 feet high, diminishing to 25 THE NEAPOLITAN VOLCANIC REGION. 37 feet, yet the rock is of so soft and easily worked a character that the labour of excavation would not be very great. Indeed, at the other end of the ridge, near the Punta di Coraglio, there is a still greater work of the same kind, forming a passage to the Villa of Lucullus. This tunnel, now called the Grotto of Sejanus, is nearly a mile in length, and was excavated by the engineer M. Coccineus, who was employed by Agrippa to cut the canal to Avernus. The Ridge of Posillipo consists of the tufaceous rock that forms the whole of the area comprising the site of Naples and the hilly district on the north- west of the city. This rock, though varying some- what in character, is essentially the same throughout, being a volcanic pumiceous agglomeration compacted together by having been deposited in the sea, as shown by its containing the shells of species of mollusca now living in the adjacent bay. In the neighbourhood it is quarried for cement, and has been used for that purpose since the days of the Romans, both Strabo and the architect Vitruvius having praised it for its still highly prized quality of cementing under water. It is widely known from the name of its place of shipment as " Pozzuolana." Near Pianura, below the hill of the Camaldoli, the rock has a more granular structure, and is there quarried for building purposes under the name of Piperno. The Pianura itself, a circular plain within the larger sweep of the Piano de Quarto, is eminently 38 MOUNT VESUVIUS. suggestive of a crater-floor. The highest point attained by the tufa hills of the district is at the Convent of the Camaldoli di Napoli, where the summit of the hill is 1,488 feet above the level of the sea, the highest eminence next Vesuvius in the district. As this tufa forms an area of many square miles, and is found to have a depth below sea-level of no less than 500 feet, while attaining so great a maximum elevation as that just stated, there is here the doubtless much-reduced presentation of an enormous aggregate amount of volcanic material, ejected long previously to the commencement of the present geographical conditions of this region. The fatal landslip at Santa Lucia in 1868 was caused by the soft character of the rock at that place, which had favoured the formation of the cracks and fissures by which the cliff behind the houses was shattered and a large mass of it thrown down. From the concentric form of the two lines of elevations at the back of Naples, that of the Castle of St. Elmo and that of the Camaldoli, there is a suggestion of an outer and an inner crater ring. Breislac, indeed, was inclined to put the number of craters, of which there were indications in the neighbourhood of Naples, including of course those undoubted ones of the Phlegraean Fields, as high as twenty-seven, but the tufa, from its soft character, is so easily acted upon by erosive agencies that some may be hollows excavated out of a great thickness of the deposit. THE NEAPOLITAN VOLCANIC REGION. 39 As remnants of volcanic activity, or rather as evidences of still continuing volcanic heat, the stufae and thermae of the Phlegraean Fields deserve attention. The chief seat of gaseous emanations, the Solfatara, has already been noticed. The fumes here evolved appear to be the same as were noted previous to the eruption of 1198, and consist of steam, sulphu- retted hydrogen, and hydrochloric acid gas. Dr. Daubeny describes a very interesting series of chemical reactions resulting in the formation of sulphates and the deposition of sulphur, which latter is a conspicuous phenomenon at the Solfatara. At the south-eastern side of Agnano, and before the drainage of the lake was commenced not far from the water's edge, the Stufe di Germano gives off vapours of sulphuretted hydrogen at 182 Fahr. Not more than a few yards distant is the well- known and much-visited Grotto del Cane, where a poor dog is alternately half suffocated and revived for the gratification of tourists more curious than humane. The gas evolved at this place is carbonic acid, produced by the decomposition of calcareous rocks below, and this, from its greater specific gravity than air, accumulates near the floor of the grotto, and so forms, as it were, an anti-vital and an anti- combustion bath. Dr. Daubeny says: "I found that phosphorus would continue lighted at about two feet from the bottom, whilst a sulphur match 4