During the years 1814-1816 Captain Smyth, acting under orders from the Admiralty, made a survey of the coast of Sicily, and of the adjacent islands. At this time the Mediterranean charts were very defective; some places on the coast of Sicily were mapped as much as twenty miles out of their true position, and even the exact positions of the observatories at Naples, Palermo, and Malta were not known. Among other results, Smyth carefully determined the latitude and longitude of Etna, accurately measured its height, and examined the surroundings of the mountain. His results were published in 1824, and are often regarded as the most accurate that we possess.
In 1824 Dr. Joseph Gemellaro, who lived all his life on the mountain, and made it his constant study, published an "Historical and Topographical Map of the Eruptions of Etna from the era of the Sicani to the year 1824." In it he delineates the extent of the three Regions, Coltivata, Selvosa, and Deserta; he places the minor cones, to the number of seventy-four, in their proper places, and he traces the course of the various lava-streams which have flowed from them and from the great crater. This map is the result of much patient labour and study, and it is a great improvement upon those of Ferrara and Recupero, but of course it is impossible for one man to survey with much accuracy an area of nearly 500 square miles, and to trace the tortuous course of a large number of lava-streams. Hence we must be prepared for inaccuracies, and they are not uncommon—the coast line is altogether wrong as to its bearings, some of the small towns on the sides of the mountain are misplaced, and but little attention has been paid to scale. Still the map is very useful, as it is the only one which shows the course of the lava-streams.
Mario Gemellaro, brother of the preceding, made almost daily observations of the condition of Etna, between the years 1803 and 1832. These results were tabulated, and they are given in the Vulcanologia dell' Etna of his brother, Professor Carlo Gemellaro, under the title of Registro di Osservazioni del Sigr. Mario Gemellaro.
Carlo Gemellaro contributed many memoirs on subjects connected with the mountain. They are chiefly to be found in the Atti dell' Accademia Gioenia of Catania, and they extend over a number of years. Perhaps the most important is the treatise entitled "La Vulcanologia dell' Etna che comprende la Topographia, la Geologia, la Storia, delle sue Eruzioni." It was published in Catania in 1858, and is dedicated to Sir Charles Lyell, who ascended the mountain under the guidance of the author. The latter also published a Breve Raggualio della Eruzione dell' Etna, del 21 Agosto 1852, which contains the most authentic account of this important eruption, accompanied by some graphic sketches made on the spot. The last contribution of Carlo Gemellaro to the history of Etna, is fitly entitled Un Addio al Maggior Vulcano di Europa. It was published in 1866, and with pardonable vanity the author reviews his work in connection with the mountain, extending over a period of more than forty years. He commences his somewhat florid farewell with the following apostrophe:—"O Etna! splendida e perenne manifestazione della esistenza dei Fuochi sotteranei massimo fra quanti altri monti, dalle coste meridionali di Europa, dalle orientali dell' Asia e delle settentrionali dell' Africa si specchiano nel Mediterraneo: tremendo pei tuoi incendii: benigno per la fertilità del vulcanico tuo terreno ridotto a prospera coltivazione . . . io, nato appiè del vasto tuo cono, in quella Città che hai minacciato più d'una volta di sepellire sotto le tue infocate correnti: allogato, nella mia prima età, in una stanza della casa paterna, che signoreggiava in allora più basse abizioni vicine, ed intiera godeva la veduta della estesa parte meridionalè della tua mole, io non potera non averti di continuo sotto gli occhi, e non essere spettatore dei tuoi visibili fenomeni!"
In 1834, M. Elie de Beaumont commenced a minute geological examination of the mountain. His results were published in 1838, under the title of Recherches sur la structure et sur l'origine du Mont Etna, and they extend over 225 pages.[11] He re-determined the latitude and longitude of the mountain, measured the slope of the cone, and the diameter of the great crater, and minutely examined the structure of the rocks at the base of the mountain. He also gives a good sectional view, elevations taken from each quarter of the compass, and a geological map, which although accurate in its general details, can scarcely be considered very satisfactory. A relief map of Etna, a copy of which is in the Royal School of Mines, was afterwards constructed from the flat map, and this was, we believe, at the same time, the first geological map, and the first map in relief, which had been made of the mountain. Elie de Beaumont considers granite as the basis of the mountain, because it is sometimes ejected from the crater; old basaltic rocks appear in the Isole dei Ciclopi, and near Paterno, Licodia, and Aderno; cailloux roulés near Motta; ancient lavas on each side of the Val del Bove; modern lavas in every part of the mountain, and calcareous and arenaceous rocks in the surrounding mountains.
In 1836, Abich published some excellent sections of Etna, and an accurate view of the interior of the crater, in a work entitled Vues illustratives de quelques Phénomènes Géologiques prises sur le Vésuve et l'Etna pendant les années 1833 and 1834.
The whole of the thirteenth volume (1839) of the Berlin Archiv für Mineralogie, Geognosie, Berghau und Hüttenkunde, is occupied by an elaborate memoir on the geology of Sicily[12] by Friedrich Hoffmann, accompanied by an excellent geological map. A long account of the geology of Etna is given, and an enlarged map of the mountain was afterwards constructed and published in the Vulkanen Atlas of Dr. Leonhard in 1850.[13]
In 1836 Baron Sartorius Von Waltershausen commenced a minute survey of Etna, preparatory to a complete description of the mountain, both geological and otherwise. He was assisted by Professor Cavallari of Palermo, Professor Peters of Hensbourg, and Professor Roos of Mayence. The survey occupied six years, (1836-1842), and the results of direct observation in the form of maps and drawings, occupied a hundred sheets 160 millimetres (6¼ inches) long, by 133 m.m. (5¼ inches) broad. Twenty-nine separate points were made use of in the triangulation; and the scale chosen was 1 in 50,000. The results were published in a large folio atlas, which appeared in eight parts; the first in 1845 and the last in 1861, when the death of Von Waltershausen put an end to the further publication. There are 26 fine coloured maps, and 31 engravings. The cost of the atlas is £12. The maps are both geological and topographical, and they are accompanied by outline engravings of various details of special interest. The Atlas des Aetna furnishes the most exhaustive history of any one mountain on the face of the earth, and Sartorius Von Waltershausen will always be the principal authority on the subject of Etna.
Sir Charles Lyell visited Etna in 1824, 1857, and again in 1858. He embodied his researches in a paper presented to the Royal Society in 1859, and in a lengthy chapter in the Principles of Geology. His investigations have added much to our knowledge of the formation and geological characteristics of the mountain, especially of that part of it called the Val del Bove.
Later writers usually quote Von Waltershausen and Lyell, and do not add much original matter. The facts of all subsequent writers are taken more or less directly from these authors. The latest addition to the literature of the mountain, is the Wanderungen am Aetna of Dr. Baltzer, in the journal of the Swiss Alpine Club for 1874.[14]