APPENDIX—GEOLOGICAL SURVEY. 
451 
came an ardent admirer of nature and a close observer of her 
phenomena. I commenced also to collect simple facts and to 
arrange them so that they would explain other things not so 
simple. In this course I was led on from one class of phenom¬ 
ena to another, gaining all the time a rich experience, and ad¬ 
ding very much to my stock of practical knowledge. Before 
I was aware of the fact, I was forming theories, not altogether 
from practical observation and mining experience, but based 
on deductions made from certain classes of facts and on prin¬ 
ciples that I found underlying certain classes of natural phe¬ 
nomena. 
In pursuing this course, I found that in all natural phenom¬ 
ena there is a chain of facts that leads unerringly, link by link, 
through the unfoldings of nature to some general laws that un¬ 
derlie them as their cause; and that it is the privilege of the 
practical miner, without a classical or scientific education to fol¬ 
low this unerring light, until he has become acquainted with 
these laws, and consequently is able to explain the phenomena 
for himself. From this stand-point, partly practical and partly 
scientific, let us take a view of mineral veins and ore deposits 
in general, and those of our own lead district in particular. 
If from the same stand-point we could see all the mineral 
veins and ore deposits opened in the crust of the earth, two 
things would especially attract our attention. In the first place 
we should notice that there is a general unity that character¬ 
izes the deposits of ore in every part of the world, as though 
they were the results of the same general laws. In the next 
place we should notice that there is a general diversity; two 
places can hardly be found that are notdistinguished from each 
other by local differences. This may seem strange to one un¬ 
acquainted with mineral strata, but it is true, and its explana¬ 
tion can be found only in the following considerations. 
Fissures and mineral veins are not one and the same thing. 
Fissures are openings or iractures in the rock, in which frac¬ 
tures or openings mineral veins or ore deposits may, or may not 
be found. Hence we find that fissures and mineral veins are 
two different things, formed at different periods by different 
