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POPULAR SCIENCE REVIEW. 
notice, and which will perhaps astonish those good folk who are pleased to 
consider the earth a mass of liquid fire which has a slight crust above it on 
which we live. It is that Mr. Scrope does not share this view of the earth’s 
constitution. He says : u It is no doubt an attractive sensational idea, that a 
molten interior to the globe underlies a thin superficial crust, its surface 
agitated by tidal waves, and flowing freely towards any issue that may here 
and there be opened for its outward escape ; but I do not think it can be 
supported by reasoning based on any ascertained facts or phenomena 
If, indeed, we are to theorise at all on the hypothesis that the earth origi- 
nated from the condensation of a mass of nebulous vapour into an incan- 
descent state, it would seem probable, as Mr. Hopkins has suggested, that 
solidification would begin at the centre and advance toward the surface, and 
that only after a long continuance of this process a time may have arrived 
when the remaining liquid matter, being of inconsiderable thickness, the 
surface also would begin to solidify by radiation of its heat into space ; 
from which time the further solidification of the interior would proceed in 
two directions — outward from the central hardened nucleus, and inward 
from the external crust.” There are many other points we should wish to 
notice, but we cannot. We must, therefore, conclude with our best thanks 
to the author for his invaluable book, and with advice to our readers to 
judge it for themselves. 
LYELL’S PRINCIPLES OF GEOLOGY.* 
T HE great master who stands at the head of all geologists, whether 
European or American, has given us once again a revised edition of his 
incomparable “ Principles of Geology.” It is with a feeling of surprise that we 
look back to the time when Lyell’s a Geology” was first issued to the English 
public. We believe it was somewhere about the year 1838, now thirty years 
ago ; and it is not without a feeling of pleasure that we witness how the 
man lias grown, so to speak, with the times, that he has modified his opinions 
as he had more light thrown in upon the subject, until he has now, in his 
eleventh edition, given us a work which for excellence of arrangement, for 
terseness of style, for beauty of illustration, for comprehensiveness of detail, 
and for general accuracy of opinion, can find no equal in the publications of 
the whole world. In this, the first volume of his u Principles,” Sir 
Charles has seen fit to modify and recast some of the chapters which ap- 
peared in the former edition nearly five years ago. During the period which 
has since elapsed, much discussion has taken place on the questions of climate 
and the temperature cf the ocean. Carpenter’s great discoveries — of which 
there is some account by their author in the present number of this journal — 
have given the geologist many facts on the temperature and shape of the ocean 
bed, and have shown that some of the animals which he was wont to con- 
sider as exclusively fossil are really living still. The physical condition of 
the Mediterranean has been well defined by these dredging explorations, and 
* u Principles of Geology ; or the Modern Changes of the Earth and its 
Inhabitants considered as illustrative of Geology.” By Sir Charles Lyell, 
Bart., M.A., F.R.S., 11th edition, vol. i. London: John Murray, 1862. 
