Here and there along the line of such a rent, cones of eruption are thrown up in succession at points where the gaseous matter obtains the freest access to the surface, and has power to force up lava and scoriæ. Few indeed, if any, of the greater volcanic mountains are unattended by such minor elevations, clustering about its sides like the satellites of a planet. Professor Dana found Mauna Loa covered with numerous parasitic cones, and Mr. Darwin counted several thousands on one of the Gallapagos Islands. On the flanks of Etna, according to Professor Sartorius von Waltershausen, more than 700 of them are to be seen, almost all possessing craters, and each marking the source of a current of lava. Though they appear but trifling irregularities when viewed from a distance as subordinate parts of so imposing and colossal a mountain, many of them would nevertheless be deemed hills of considerable height in almost any other region. The double hill near Nicolosi, called Monte Rossi, formed in 1669, is 450 feet high and two miles in circumference at its base; and Monte Minardo, near Bronte, on the east of the great volcano, is upwards of 700 feet in height.[8] Footnote 8: See p. 67. ‘On looking down from the lower borders of the desert region of Etna,’ says Sir Charles Lyell, ‘these minor volcanoes, which are most abundant in the woody region, present us with one of the most delightful and characteristic scenes in Europe. They afford every variety of height and size, and are arranged in beautiful and picturesque groups. However uniform they may appear when seen from the sea, or the plains below, nothing can be more diversified than their shape when we look from above into their craters, one side of which, as we have seen, is generally broken down. There are indeed, few objects in nature more picturesque than a wooded volcanic crater. The cones situated in the higher parts of the forest zone are chiefly clothed with lofty pines, while those at a lower elevation are adorned with chestnuts, oaks, and beech-trees.’ As the point where a lava-current finds a vent is often situated at a considerable distance below the surface of the liquid column in the internal chimney of the volcano, the pressure from above not seldom causes the lava to spout forth in a jet, until its level in the crater shaft has been reduced to that of the newly-formed orifice. Thus, when Vesuvius was rent by the dreadful paroxysmal eruption of 1794, the lava was seen to shoot up in magnificent fountains as it issued from the openings along the fissure.