286 SIR RODERICK I. MURCHISON’S ADDRESS— EUROPE. [May 24, 1858. 
springs, springs of vapour and gas (salses, mud volcanos, naphtha 
flames), and volcanos. The last are described under various heads, 
in each of which the direct connexion between the modus operandi 
(whether in geological and pre-historic times, or in the present 
period) and the geographical outlines of the earth is admirably sus- 
tained, both from the vast range of personal observation of the author, 
and from the citation of all those who have studied such works 
of nature. Although it is impossible to do more on this occasion 
than stimulate my hearers to read this most instructive volume, of 
which an excellent translation (with lucid annotations) has been 
produced by our associate General Sabine, I may specially call 
your attention to the sketch of the geographical distribution of 
volcanos. Humboldt estimates that out of 407 volcanos, 225 have 
been in activity in vety modern times; and of these, 198, or -|ths 
of the whole, lie within the great “Pacific Basin.” One of the 
important generalizations which he is disposed to draw, from a 
consideration of their prevalent linear direction, is, that islands 
and coasts are richer in these outbursts, because, to use his own 
words, “ The upheaval effected by internal elastic forces is accom- 
panied by adjacent depression in the bed of the sea, so that an area 
of elevation borders on an area of depression, the limit between 
them exhibiting profound clefts and fissures.” 
After minutely examining the chemical and mineralogical charac- 
ters of the rocks produced by volcanic action, and doing all justice 
to the new classification of volcanic rocks by M. Gustaf Eose, 
Humboldt concludes this volume by pointing out the importance 
and extent of the eruptions of molten matter through the great 
clefts or fissures above spoken of. “ He has been led (he says) 
to entertain the conjecture that a not inconsiderable portion— 
perhaps, according to volume, the larger portion — of volcanic rocks 
have been emitted, not from elevated volcanic frameworks, but 
from a net- work of fissures, on the earth’s surface, from which they 
have poured forth, often forming strata covering an extent of many 
square leagues.”— (English Edition, Sabine, p. 448.) 
In a conversation which I held with my venerable friend in 
Potsdam in September last, just as he was entering his 88th year, 
he explained to me some of these views with his accustomed clear- 
ness and freshness of description ; and I then had the satisfaction to 
find, that in addition to the remarkable volume now issued, a second 
part would soon follow, in which all organic nature, from its earliest 
traces in sedimentary strata to the present day, will be exhibited in 
