observation in the form of maps and drawings, occupied a hundred sheets
160 millimetres (6-1/4 inches) long, by 133 m.m. (5-1/4 inches) broad.
Twenty-nine separate points were made use of in the triangulation; and
the scale chosen was 1 in 50,000. The results were published in a large
folio atlas, which appeared in eight parts; the first in 1845 and the
last in 1861, when the death of Von Waltershausen put an end to the
further publication. There are 26 fine coloured maps, and 31 engravings.
The cost of the atlas is L12. The maps are both geological and
topographical, and they are accompanied by outline engravings of various
details of special interest. The _Atlas des Aetna_ furnishes the most
exhaustive history of any one mountain on the face of the earth, and
Sartorius Von Waltershausen will always be the principal authority on
the subject of Etna.

Sir Charles Lyell visited Etna in 1824, 1857, and again in 1858. He
embodied his researches in a paper presented to the Royal Society in
1859, and in a lengthy chapter in the _Principles of Geology_. His
investigations have added much to our knowledge of the formation and
geological characteristics of the mountain, especially of that part of
it called the Val del Bove.

Later writers usually quote Von Waltershausen and Lyell, and do not add
much original matter. The facts of all subsequent writers are taken more
or less directly from these authors. The latest addition to the
literature of the mountain, is the _Wanderungen am Aetna_ of Dr.
Baltzer, in the journal of the Swiss Alpine Club for 1874.[14]

[14] Jahrbuch des Schweizer Alpen Club. Neunter Jahrgang, 1873-1874.
Bern 1874.

A fine map of Sicily, on the unusually large scale of 1 in 50,000, or
1.266 inch to a mile, was constructed by the Stato Maggiore of the
Italian government, between 1864 and 1868. The portion relating to Etna,
and its immediate surroundings occupies four sheets. All the small roads
and rivulets are introduced; the minor cones and monticules are placed
in their proper positions, and the elevation of the ground is given at
short intervals of space over the entire map. An examination of this map
shows us that distances, areas, and heights, have been repeatedly
misstated, the minor cones misplaced, and the trend of the coast line
misrepresented. For example, if we draw a line due north and south
through Catania, and a second line from the Capo di Taormina, (the
north-eastern limit of the base of