270 On forming Collections of Geological Specimens. 
ness to either of these sciences is unquestionable*. In geology, 
however, it is as likely to mislead, as to conduct us to the proper 
end of our researches, unless it be directed to its proper object. 
The most important, and by far the most interesting part of 
geology, is that which describes and determines the relative ages 
of the strata which form the superficial crust of the earth ;—to 
these strata we must look for a history of the changes which the 
surface of the earth has undergone. 
The limited powers which we possess of gaining information, 
renders it necessary that we should examine with the most care- 
ful attention the means which we have, and that we should ap- 
ply them in the best manner to account for the phenomena. 
The nature of the organic remains that are found imbedded 
in many of the strata, appears to have been considered capable of 
throwing some important lights on this subject, by many writers, 
who seem, however, to have had no correct ideas respecting the 
manner of rendering this kind of knowledge useful, and their 
statements are general and incorrect ; such as must ever arise 
from limited and hypothetical views of a subject. 
It is to the meritorious exertions of Messrs. Smith, Sowerby, 
and Parkinson, that we are chiefly indebted for the true applica- 
tion of mineral conchology in explaining the structure of the 
earth; but more particularly to Messrs. Smith and Sowerby, 
who have directed their attention to the subject, with the view 
of rendering it useful in identifying the strata. 
Mr. Parkinson’s ** Organic Remains of a Former World”’ has 
been some years before the public: in this work he has given 
the localities of many shells, but not often their places in the 
strata. 
Mr. Farev has laid before your readers + an alphabetical list of 
the places where the shells were found, that are described in the 
first volume of Mr, Sowerby’s “ Mineral Conchology,” with the 
sittations of the places, the names of the shells, and the places 
in the British series of strata to which they belong—this latter 
object having been but imperfectly accomplished in the text of 
the “* Mineral Couchology.”’ 
Since that period Mr. Sowerby’s collection has been much 
increased by the contributions of the friends of science, and he 
has now published the xxxth number of his “ Mineral Con- 
chology.” 
* Many valuable analyses of minerals are extremely unsatisfactory, from 
the want of a correct description of the specimens analysed. This neglect 
has been very justly censured by an able cheinist, (Annals of Phil. No. 52, 
p- 332,) whose example, in this respect, is well worthy of imitation; as 
well as his manner of describing minerals, which is a modification of that 
followed by the excellent Kirwan. 
+ Philosophical Magazine, vol. xlvi. p. 211. 
Also, 
