Maclure’s Letiers. 159 
own superiority, and to the vast advantages they enjoy, in the 
simplieity, regularity, and undisturbed state of the stratification 
of our field of observation. It will give them a proper con 
dence in their own powers, and teach them the real value of 
those European theories, fabricated in cabinets, ongnating 
more out of literature than science, and more indebted to the 
pen than the hammer, perverting the few accurate obteia 
tions that care come within the sphere of their knowledge, to 
suit the arrangement of their circumscribed field, distorting 
and crowding all observations to suit the model fo rmed by their 
imaginations and squaring the stratification of the globe, by 
e imperfect knowledge they have acquired of their own 
districts. 
_ Confidence in theories is Santi AL in the exact ratio of 
ignorance in practice ; some mineralogical travellers in Amer- 
ica do not soar above: the level of mineral merchants, or per- 
hapsof the agent of such merchants, who, tempted by the vast 
number and variety of the cabinet specimens ehaeel by 
the industry and science of our young mineralogists, make it 
their great object to form such abundant collections of speci- 
mens, as the unsuspicious communications of our observers 
may enable them to do—(for the number of our amateurs is 
very great and they are scattered all over the continent ;) thus 
they fill the foreign mineral shops with specimens, and their 
own pockets with money, perhaps laughing in their sleeves, 
in the mean time, at our credulity, in taking them for men of 
science, while under the cloak of that name, their only object 
was a mercantile speculation. 
In sketching some years since, the outlines of our stratifi- 
cation, in the boundaries or limits of the different classes of 
rocks, I have no doubt, that I may have committed many errors; 
but the sense of our practical geologists is safe from the de- 
lusion of chimerical cabinet systems, formed by speculation 
on Ae a eae oa localities 
haps, warranted in thinking, that the mass of 
Soleical facts, siresily collected, and augmenting every ays 
puts our students out of the reach of quackery, and o 
aginary theories, and that nothing but well Gthenticated 
practical facts can have any weight with them 
The thirty or forty cases of geological specimens, which I 
ee br a to support my sketch of our geology, 
now lodge the collection of the academy of Natural 
Bitbniies in Philadelphia) will, I presume, remain unchang- 
