The highest crater of the peak has merely disengaged sulphureous vapors
ever since it has been known to Europeans; but an eruption happened in
June, 1798, not far from the summit, and others are recorded, which
poured out streams of lava from great heights, besides many which have
broken out nearer the level of the sea. All these, however, seem to be
dependent on one great centre of eruption, or on that open channel
communicating between the interior of the earth and the atmosphere,
which terminates in the highest crater of the peak.

We may consider Teneriffe, then, as having been from a remote period the
principal and habitual vent of the volcanic archipelago of the Canaries.
The discharges which have taken place in the contiguous isles of Palma,
Lancerote, and the rest, may be of a subsidiary kind, and have probably
been most frequent and violent when the greater crater has been
partially sealed up, just as the violent eruptions of Ischia or that of
Monte Nuovo coincided with the dormant state of Vesuvius.

SANTORIN.

The Gulf of Santorin, in the Grecian Archipelago, has been for two
thousand years a scene of active volcanic operations. The largest of the
three outer islands of the group (to which the general name of Santorin
is given) is called Thera (or sometimes Santorin), and forms more than
two-thirds of the circuit of the gulf (see Map, fig. 63, p. 442). The
length of the exterior coast-line of this and the other two islands
named Therasia and Aspronisi, taken together, amounts to about thirty
miles, and that of the inner coast-line of the same islands to about
eighteen miles. In the middle of the gulf are three other islands,
called the Little, the New, and the Old "Kaimenis," or "Burnt Islands."
The accompanying map has been reduced from a recent survey executed in
1848 by Captain Graves, R. N., and shortly to be published by the
Admiralty.

[Illustration: Fig. 63.

Map of Santorin in the Grecian Archipelago, from a Survey in 1848, by
Captain Graves, R. N.

_The soundings are given in fathoms._

A, Shoal formed by submarine volcanic eruption in 1650.
B, Northern entrance.
C, Mansell's Rock.
D, Mount St. Elias, 1887 feet high.

]

[Illustration: Fig. 64.

Section of Santorin, in a N. E. and S. W. direction, from Thera through
the Kaimenia to Aspronisi.]

[Illustration: Fig. 65.

Part of the section, fig. 64, enlarged.]

Pliny informs us that the year 186, B. C., gave birth to