Page:Encyclopædia Britannica, Ninth Edition, v. 8.djvu/654

Rh 630 ETNA stiff piece of work. It consists of loose ashes and blocks of lava, and it slopes at an angle of &quot; 45 or more,&quot; accord ing to one writer, and of 33, according to another. Pro bably the slope varies on different sides of the cone ; on the side the ascent described was made the 45 certainly seem? the more probable. Fortunately there was no strong wind, and no experience of the sickness of which travellers constantly complain in the rarefied air of the summit. The highest point was reached at 4.30 A.M., temperature 47 Fahr. Steam and sulphurous acid issued from the ground, and the cinders were so hot in some places that it was necessary to choose a cool place to sit down on. A thermometer inserted just beneath the soil from which steam issued registered 182 Fahr. Nearly all the stars had now faded away. The vault of heaven was a pale blue, becoming a darker and darker grey towards the west, where it was nearly black Just before sunrise the sky had the appearance of an enormous arched spectrum extremely extended at the blue end. Above the place where the sun would presently appear there was a brilliant red, shading off in the direction of the zenith to orange and yellow; the latter was succeeded by pale green, this by a long stretch of pale blue, then darker blue, and dark grey, ending opposite to the rising sun with black. This effect was quite distinct; it lasted some minutes, and was very remarkable. It was succeeded by the usual rayed appear ance of the rising sun, and at ten minutes to 5 o clock the upper limb of the sun was seen above the mountains of Calabria. Examined by the spectroscope, the Fraunhofer lines were extremely distinct, particularly two lines near the red end of the spectrum. The top of the mountain was now illuminated, while all below was in comparative dark ness, and a light mist floated over the lower regions. The party was so fortunate as to witness a phenomenon which is not always visible, viz., the projection of the shadow of the mountain across the island, an hundred miles away. The shadow appeared to be vertically suspended in space, at or beyond Palermo, and to be resting on a slightly misty atmosphere ; it gradually sank until it reached the surface of the island, and as the sun rose, the shadow of course approached nearer and nearer to the base of the mountain. In a short time the flood of light dastroyed the fine effects of light and shadow which were at first visible. The mountains of Calabria appeared very close ; the east coast of Sicily could be traced until it ended at Cape Passaro and turned to the west, forming the southern boundary of the island, while to the west distant mountains appeared. The crater was then examined, a vast abyss nearly 1000 feet in depth, shut in by precipitous sides. Its dimensions vary, but it is now between two and three miles in circum ference. Sometimes it is nearly full of lava, at other times it appears to be bottomless. At the present time it is like an inverted cone ; its sides are covered with incrustations of sulphur and ammonia salts, and jets of steam perpetually issue from crevices in its sides. Near the summit was found a deposit several inches in thickness of a white substance, apparently lava decomposed by the hot effluent gases. Hydrochloric acid is said to frequently issue from the crater ; the most abundant gases appeared to be sul phurous acid and steam. The interior of the crater reminds one _ in many respects of the Solfatara near Puzzuoli. During the descent from the cone various specimens of ash and cinder were collected some red, others black and very vesicular, others highly crystalline, some pale pink. The steep slope of the cone was well shown by the fact that although the surface is either extremely rugged owing to the accumulation of masses of lava, or soft and yielding on account of the accumulation of cinders, a large mass of lava, set rolling near the summit, rushes down with increasing velocity until it bounds off to the plain below. A striking feature presented during the descent from the mountain was the apparent nearness of the minor cones below, and of the villages at the base of the mountain. The latter seemed to be painted on a vertical wall, and although from ten to fifteen miles distant, they appeared almost within a stone s throw. This curious effect, which has often been observed before, is due to atmospheric refraction. The different specimens of lava were found to present a wonderful similarity of structure and composition. The main constituents are olivine, magnetite, and felspar. The crystals of the latter are much larger in some specimens than in others. Sometimes olivine prevails, sometimes felspar. A specimen of lava of 1535 found near Borello was ground until it was sufficiently transparent to be examined under the microscope by polarized light. It was found to contain good crystals of augite and olivine, and well striated labradorite and magnetite. Eruptions. A list of all the eruptions of Etna from the earliest times, has been given by several writers, notably by Ferrara in his Dcscrizione dell Etna, and by Gemellaro. The first eruption within the historical period probably happened in the 7th century B.C.; the second occurred in the time of Pytha goras. The third eruption, which occurred in 477 B.C., is men tioned by Thucydides, and it must be the eruption to which Pindar and JSschylus allude. An eruption mentioned by Thucydides occurred in the year 426 B.C. An outburst of lava took place from Monte di Mojo, the most northerly of the minor cones of Etna, in 396 B.C., and following the course of the river Acesines (now the Alcantara) entered the sea near the site of the Greek colony of Naxos (now Capo di Schiso). We have no record of any further eruption for 256 years, viz., till the year 140 B.C. Six years later an eruption occurred, according to Orosius and Julius Obsequens; and Fulvius Flaccus and the same authorities men tion an eruption in the year 126 B.C. Four years later Katana was nearly destroyed by a new eruption, 122 EC. An erup tion, of which we possess no details, occurred during the civil war between Crcsar and Pompey, 49 B.C. Livy speaks of an eruption and earthquake which took place (43 B.C.) shortly before the death of Ctesar, which it was believed to portend. In 38 B.C. and 32 B.C. eruptions occurred. The next eruption of which we hear is that mentioned by Suetonius in his life of Caligula. This was in 40 A.D. An eruption is stated to have occurred in 72 A.D. after which Etna was quiescent for nearly two centuries, but in the year 253, in the reign of the emperor Decius, a violent erup tion lasting 9 days occurred. According to Carrera and Photius, an eruption occurred in the year 420. We now find no further record for nearly 400 years. Geoffrey of Viterbo states that an eruption occurred in 812, when Charlemagne was in Messina. After another long interval, in this case of more than three centuries and a half, the mountain again entered into eruption. In February 1169 one of the most disastrous eruptions on record occurred. A violent earthquake, which was felt as far as Reggie, destroyed Catania in the course of a few minutes, burying 15,000 persons beneath the ruins. It was the vigil of the feast of St Agatha, and the cathedral of Catania was crowded with people, who were all buried beneath the ruins, together with the bishops and forty-four Benedictine monks. The side of the cone of the great crater towards Taorminn, fell into the crater. According to Nicola- Speziale, there was a great eruption from the eastern side of the mountain in 1181. Lava descended from the eastern side of the mountain in 1285 ; in 1329 Nicola Speziale was in Catania, and he witnessed a very violent eruption, of which he has left us an account. On the evening c-f June the 28th, about the hour of vespers, Etna was strongly con vulsed, terrible noises were emitted, and flames issued from the south side of the mountain. A new crater, Monte Lepre, opened near the Val del Rue, above the rock of Musarra, and emitted large quantities of dense black smoke. Soon afterwards a torrent of lava poured from the crater, and red hot masses of rock were pro jected into the air. Four years after the last eruption, l is recorded by Silvaggio that a fresh outburst took place. A manuscript preserved in the archives of the cathedral of Catania mentions an eruption which occurred on the 6th of August 1371, which caused the destruction of numerous olive groves near the city. An erup tion which lasted for twelve days commenced in November 1408. A violent earthquake in 1444 caused the cone of the mountain to fall into the great crater. An eruption of short duration, of whici. we have no details, occurred in 1 447. After this Etna was quiescent for 89 years. Cardinal Bembo and Fazzello mention an eruption which occurred towards the close of the 15th century. In March 1536 a quantity of lava issued from the great crater, and several new apertures opened near the summit of the mountain and