antara,
(immediately beyond which Monte di Mojo, the most northerly minor cone
of Etna is situated), as the northern boundary, and the river Simeto as
the boundary on the west and south, we obtain a circumference of 91
miles for the base of Etna. In this estimate the small sinuosities of
the river have been neglected, and the southern circuit has been
completed by drawing a line from near Paterno to Catania, because the
Simeto runs for the last few miles of its course through the plain of
Catania, quite beyond the most southerly stream of lava. The Simeto
(anciently _Simaethus_) is called the Giaretta along the last three miles
of its course, after its junction with the Gurna Longa.

The area of the region enclosed by these boundaries is approximately 480
square miles. Reclus gives the area of the mountain as 1,200 square
kilometres--461 square miles. (_Nouvelle Geographie Universelle_, 1875.)
The last edition of a standard Gazetteer states it as "849 square
miles;" but this estimate is altogether absurd. This would require a
circle having a radius of between sixteen and seventeen miles. If a
circle be drawn with a radius of sixteen miles from the crater, it will
pass out to sea to a distance of 4-1/2 miles on the East, while on the
West and North it will pass through limestone and sandstone formations
far beyond the Alcantara and the Simeto, and beyond the limit of the
lava streams.

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 sid