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]

A fine map of Sicily, on the unusually large scale of 1 in 50,000, or 1·266 inch to a mile, was constructed by the Stato Maggiore of the Italian government, between 1864 and 1868. The portion relating to Etna, and its immediate surroundings occupies four sheets. All the small roads and rivulets are introduced; the minor cones and monticules are placed in their proper positions, and the elevation of the ground is given at short intervals of space over the entire map. An examination of this map shows us that distances, areas, and heights, have been repeatedly misstated, the minor cones misplaced, and the trend of the coast line misrepresented. For example, if we draw a line due north and south through Catania, and a second line from the Capo di Taormina, (the north-eastern limit of the base of Etna), until it meets the first line at Catania, the lines, will be found to enclose an angle of 26°. If we adopt the same plan with Gemellaro's map, the included angle is found to be 53°, and in the case of the maps of Ferrara and Recupero more than 60°. Again, it has been stated on good authority, that the lava of 396 b.c. which enters the sea at Capo di Schiso flowed for a distance of nearly 30 miles; the map shows us that its true course was less than 16 miles. Lyell in 1858 gives a section of the mountain from West 20° N., to East 20°