410 
SECOND REPORT- 1832. 
amphitheatres of many leagues in diameter, encircling central 
conical craters; of lines of these generally disposed in a linear 
direction ; of such linear trains often radiating from a central 
focus of principal disturbance ; we may almost fancy that this 
description was intended as an exact portrait of what we ob¬ 
serve on the lunar surface. Is it, then, altogether unfounded to 
believe that by more carefully observing these phenomena, 
where we have a whole hemisphere of a planet at once open to 
our inspection,—by comparing the best of the early delinea¬ 
tions of its telescopic appearance, with its exact actual forms, 
and watching diligently those forms, so that we may be able to 
detect any changes in them,“—is it too much to hope that we 
may thus effectually extend our knowledge of the general laws 
of the volcanic forces, which should appear to be among the 
general planetary phenomena * ? 
The great branches of the comparative geology, and com¬ 
parative palaeontology (or study of fossil remains) of distant 
countries, much as they have recently advanced, have as yet 
even a still wider interval to pass over than that which they 
may have already accomplished, before they shall have obtained 
that degree of completeness which alone can qualify them to 
serve as sound bases in any geological theory. 
First, as to comparative geology. The very introductory ques¬ 
tion is yet inadequately answered. Is there or is there not any¬ 
thing like such a general uniformity of type in the series of rock 
formations in distant countries, that we must conceive them to 
have resulted from general causes, of almost universal preva¬ 
lence at the same geological asras ? Now it is clear that this 
question, if intelligently proposed, does not require, for its affir¬ 
mative solution, anything like an exact identity of formations in 
remote localities. It does not require anyone to be able to take to 
Australia a detailed list of English strata, and to be able at once 
to lay his hands on the exact equivalents of our lias, oolites, and 
chalk. Such an idea would be almost to caricature the Werne¬ 
rian dogma of universal formations. We are indeed unable to 
trace many of these formations, even through our own island, 
without observing such considerable modifications in their com¬ 
parative types, in our northern and southern counties, as may 
sufficiently remind us that we are to look only for such ana¬ 
logous rather than identical results, as would naturally proceed 
* The ancient selenographical maps of Hevelius, Ricciolus, and Cassini, are 
too defective in precision of outline to be of much use. Russel’s lunar globe and 
Schrceter’s detailed plates afford every desirable information; and Mr. Blunt 
has recently published in a cheaper form a very beautiful engraving on a single 
sheet, extremely accurate, and amply sufficient for the purpose. 
