The extent of radius of vision from the summit of Etna is very variously stated. The exaggerated notions of the earlier writers, that the coast of Africa and of Greece are sometimes visible, may be at once set aside. Lord Ormonde's statement that he saw the Gulf of Taranta, and the mountains of Terra di Lecce beyond it--a distance of 245 miles--must be received with caution. It is, however, a fact that Malta, 130 miles distant, is often visible; and Captain Smyth asserts that a considerable portion of the upper part of the mountain may sometimes be seen, and that he once saw more than half of it, from Malta, although that island is usually surrounded by a sea-horizon. It is stated on good authority that Monte S. Giuliano above Trapani, and the OEgadean Isles, 160 miles distant, are sometimes seen. Other writers give 128 miles as the limit. The fact is, that atmospheric refraction varies so much with different conditions of the atmosphere that it is almost impossible to give any exact statement. The more so when we remember that there may be many layers of atmosphere of different density between the observer and the horizon. Distant objects seem to be just under one's feet when seen from the summit of the mountain. Smyth gives the radius of vision as 150·7 miles: and this we are inclined to adopt as the nearest approach to the truth, because Smyth was an accurate observer, and he made careful corrections both for error of instruments and for refraction. This radius gives an horizon of 946·4 miles of circumference, and an included area of 39,900 square miles--larger than the area of Ireland. If a circle be traced with the crater of Etna as a centre, and a radius of 150·7 miles, it will be found to take in the whole of Sicily and Malta, to cut the western coast of Italy at Scalca in Calabria, leaving the south-east coast near Cape Rizzuto. Such a circle will include the whole of Ireland, or if we take Derby as the centre, its circumference will touch the sea beyond Yarmouth on the East, the Isle of Wight on the South, the Irish Channel on the West, and it will pass beyond Carlisle and Newcastle-on-Tyne on the North. The road which surrounds the mountain is carried along its lower slopes, and is 87 miles in length. It passes through the towns of Paterno, Aderno, Bronte, Randazzo, Linguaglossa, Giarre, and Aci Reale. It is considered by some writers to define the base of the mountain, which is hence most erroneously said to have a circumference of 87 miles; but the road frequently passes over high beds of lava, and winds considerably. It is about 10 miles from the crater on the North, East, and West sides, increasing to 15-1/2 miles at Paterno, (S.W.). The elevation on the North and West flanks of the mountain is nearly 2,500 feet, while on the South it falls to 1,500 feet, and on the East to within 50 feet of the level of the sea. It is quite clear that it cannot be asserted with any degree of accuracy to define the base of the mountain.