400 JOURNAL OF SCIENCE, 
fully complex animal and vegetable life, always in harmony 
with the conditions of the earth’s surface, gradually and during 
untold ages reaching, by evolution, the present stage of existence 
and perfection. 
It would lead me too far to enter into a discussion of all the 
theories advanced as to the cause or causes by which mountain 
chains and seas have been formed, and volcanoes and earth- 
quakes—because in most instances the two latter are intimately 
connected with each other—have been originated. Elie de Beau- 
mont’s theory of the sudden upheaval of parallel mountain chains, 
first published in 1833, although at one time finding great favour 
on the continent of Europe, was never adopted by any English 
geologist of note, the teachings of Hutton and Lyell leaving no 
room for the doctrines of the paroxysmal school. Moreover, 
when the size and direction of mountain chains were taken into 
account, and the rocks composing them were carefully examined, 
it was found that the explanations offered by the eminent French 
geologist could not be adopted. 
Many valuable publications have been issued upon these 
subjects, of which those of Robert Mallet may in many respects 
claim our greatest attention. Another work of great value is that 
of Professor E. Suess, the eminent Professor of Geology in the 
University of Vienna, “Die Entstehung der Alpen,” the 
formation of the Alps, in which this difficult question is treated 
in a masterly manner. Professor Green’s “ Physical Geology” 
contains also an exhaustive resumé of the physics of the earth’s 
crust, in which all the newest researches and theories are 
thoroughly examined and sifted by an excellent observer and 
practical geologist. However, there is another distinguished 
geologist and physicist, Constant Prevost, whom I should not 
omit to mention, he having already explained, in 1822, the eleva- 
tion of mountain chains by tangential and lateral pressure, now 
mostly adopted as the correct theory. The deep-sea dredgings 
have also offered us considerable material to elucidate the former 
history of our globe, both from a strati-graphical and palzeonto- 
logical point of view. : 
The oscillation of land and sea is another subject of great 
importance that has hardly received that attention it deserves, 
whether we take the so-called glacial period into account or 
not. There may be with many geologists the fear of appearing 
heterodox if they state their belief that the hydrosphere is, like 
the lithosphere, subjected to considerable oscillations, by which 
great changes in the climate of the globe may have been brought 
about in past geological ages. For years I have held and 
stated this opinion. 
However, I find thatlatelyagreatdeal of attentionhas been paid 
to this subject. Thus, for instance, Ph. Fischer, Heinrich Bruns, 
and others, in discussing pendulum observations, have come to 
the conclusion that the sea-level is mot a regular spheroid, but 
may vary many hundreds of feet even along the same parallel of 
latitude. Dr. Penck will also explain raised beaches and other 
ve £ 
