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,