There are two cities, Catania and Aci Reale, and sixty-two towns or villages on Mount Etna. It is far more thickly populated than any other part of Sicily or Italy, for while the population of the former is 228 per square mile, and of the latter 233, the population of the habitable zone of Etna amounts to 1,424 per square mile. More than 300,000 persons live on the slopes of the mountain. Thus with an area rather larger than that of Bedfordshire (462 square miles) the mountain has more than double the population; and with an area equal to about one-third that of Wiltshire, the population of the mountain is greater by nearly 50,000 inhabitants. We have stated above that the area of Etna is 480 square miles, but it must be borne in mind that the habitable zone only commences at a distance of about 9-1/4 miles from the crater. A circle, having a radius of 9-1/4 miles, encloses an area of 269 square miles; and 480 minus 269 leaves 211 square miles as the approximate area of the habitable zone. Only a few insignificant villages on the East side are nearer to the crater than 9-1/4 miles. Taking the inhabitants as 300,000, we find, by dividing this number by 211, (the area of the habitable zone), that the population amounts to 1,424 per square mile. Even Lancashire, the most populous county in Great Britain, (of course excepting Middlesex), and the possessor of two cities, which alone furnish more than a million inhabitants, has a population of only 1,479 to the square mile. Some idea of the closeness of the towns and villages may be found by examining the south-east corner of the map. If we draw a line from Aci Reale to Nicolosi, and from Nicolosi to Catania, we enclose a nearly equilateral triangle, having the coast line between Aci Reale and Catania as its third side. Starting from Aci Reale with 24,151 inhabitants, and moving westwards to Nicolosi, we come in succession to Aci S. Lucia, Aci Catena, Aci S. Antonio, Via Grande, Tre Castagni, Pedara, Nicolosi, completing the first side of the triangle; then turning to the south-east and following the Catania road, we pass Torre di Grifo, Mascalucia, Gravina, and reach Catania with 85,055 inhabitants; while on the line of coast between Catania and Aci Reale we have Ognina, Aci Castello, and Trezza. Within the triangle we find Aci Patane, Aci S. Filippo, Valverde, Bonacorsi, S. Gregorio, Tremestieri, Piano, S. Agata, Trappeto, and S. Giovanni la Punta: in all twenty-five, two of which are cities, several of the others towns of about 3,000 inhabitants, and the rest villages. These are all included within an area of less than thirty square miles, which constitutes the most populous portion of the habitable zone of Etna. That the population is rapidly increasing is well shown by a comparison of the number of inhabitants of some of the more important towns in 1824 and in 1876.[15] _1824_ _1876_