by Professor Playfair in his work entitled,
_Illustrations of the Huttonian Theory of the Earth_,[8] although other
observers, such as Desmarest, Collini, and Guettard, had in other
countries come to very clear views on this subject.

The following are some of the more important works on the phenomena of
volcanoes and earthquakes published during the present century:--[9]

1. Poulett Scrope, F.R.S., _Considerations on Volcanoes_ (1825). This
work is dedicated to Lyell, his fellow-worker in the same department of
science, and was undertaken, as he says, "in order to help to dispel
that signal delusion as to the mode of action of the subtelluric forces
with which the Elevation-Crater theory had mystified the geological
world." The second edition was published in 1872.

2. This was followed by the admirable work, _On the Extinct Volcanoes
of Central France_, published in 1826 (2nd edition, 1858), and is one of
the most complete monographs on a special volcanic district ever
written.

3. Dr. Samuel Hibbert, _History of the Extinct Volcanoes of the Basin of
Neuwied on the Lower Rhine_ (1832). Dr. Hibbert's work is one of
remarkable merit, if we consider the time at which it was written. For
not only does it give a clear and detailed account of the volcanic
phenomena of the Eifel and the Lower Rhine, but it anticipates the
principles upon which modern writers account for the formation of river
valleys and other physical features; and in working out the physical
history of the Rhine valley below Mainz, and its connection with the
extinct volcanoes which are found on both banks of that river, he has
taken very much the same line of reasoning which was some years
afterwards adopted by Sir A. Ramsay when dealing with the same subject.
It does not appear that the latter writer was aware of Dr. Hibbert's
treatise.

4. Leopold von Buch, _Description Physique des Iles Canaries_ (1825),
translated from the original by C. Boulanger (1836); _Geognostische
Reise_ (Berlin, 1809), 2 vols.; and _Reise durch Italien_ (1809). From a
large number of writings on volcanoes by this distinguished traveller,
whom Alexander von Humboldt calls "dem geistreichen Forscher der Natur,"
the above are selected as being the most important. That on the Canaries
is accompanied by a large atlas, in which the volcanoes of Teneriffe,
Palma, and Lancerote, with some others, are elaborately represented, and
are considered to bear out the author's views regar