38 
THE GEOLOGIST. 
numerous ; experienced geologists ever must be few, No men possess , 
greater advantages for obtaining and elaborating some at least of the re- 
quired facing-stones of the huge superstructure of geology than the Di- 
rectors of National Surveys, no other men have tlie means at their disposal 
in time, money, or assistance, still less of obtaining the intercommuni- 
cation with foreign surveys ; but instead of grand works such as Agassiz'i 
' Fossil Fishes,' Hutton's ' Coal Plants,' Owen's ' Odontography,' D'Or-l 
bigny's ' Palaeontology of France,' Mallet's ' Earthquake Phenomena,' andj 
the publications of the Palaeontographical Society, we must be content toj 
buy for our children the " little books " which those great men we wish tol 
look up to, write for our publishers. Luckily, we have no reason to dread^ 
a Murchison penning a geological primer for infant schools. 
But to take the book as it is, and to view it as one for those who have 
not time for much study, it is better calculated to give the best running 
notion of geology with the least amount of trouble of any book we know. 
The popular doctrines of geology are fairl}'- and moderately put, and al- 
though adhering to many of the views which we ourselves have shown a 
strong antagonism to in the pages of this journal, Mr. Jukes puts them! 
fairly, and, for a school treatise, properly. Such a work is not an arena fon 
controversy, nor would it be fitting in it to go too strongly against the 
stream of general belief, and it is therefore better and wiser to teach whati 
is generally accepted, and when to that which is not certain the author 
adds a statement to that eiFect, he has done all that is required of him.' 
This Mr. Jukes does most fairly, according to his conscience. Take the| 
account of the igneous rocks as an example, on which, after stating the 
grounds which geologists urge for a molten state of the interior of the 
globe, and showing that if the temperature increased regularly with 
depth, as it is supposed to do, say 1° F. for every 100 feet, or 52° F. fori 
every mile, that at four miles deep water would be at boiling-point, at fifty 
miles the heat would be sufficient to melt steel, and that at a hundred! 
miles the temperature would be 5000° F., which, Mr. Jukes says, is "greater] 
than any that we know at the surface." ; 
" It is not by any means necessary, however, to suppose that the temperature does in- 
crease indefinite]}^ into the interior, or that the rate which regulates its increase near the 
surface continues to he the same for such depths as those mentioned above. Neither 
does it follow that the materials, whatever they may be, which exist at great depths, 
would be melted by the same amount of heat that would fuse them at the surface, since 
the enormous amount of pressure which they must experience, may kep,p them solid in 
spite of the heat." 
After this usual supposititious evasion of the discussion of the great diffi- 
culties attending the " molten interior " doctrine, Mr. Jukes praise worthily 
adds a concluding sentence to his chapter : — 
"Little or nothing," he says, "is known about the constitution or condition of the , 
interior, nor have we any grounds even for speculation, further than those which have 
been previously mentioned." 
The same moderate expression of views of which we have given an ex- 
ample from the first pages, continues throughout to the end, and from the 
last page we take another similar extract : — 
" The term 'transition' was at one time used to designate an imaginary period between 
that of the formation of the so-called crystalline rocks and the others. Part of the same 
prejudice still lingers amongst geologists, and induces them to regard the present time as 
distinct from the Tertiary epoch, and to introduce such terms as Post-Tertiary or 
Quaternary." 
