396 
WISCONSIN STATE AGRICULTURAL SOCIETY. 
and forces with which productive mineral veins always stand 
connected. 
To do this, I will avail myself of the analogy that exists 
between the physical conditions of the mineral kingdom, and 
the physical conditions of the vegetable kingdom, for we are 
more familiar with the latter than with the former, and the 
illustrations which it furnishes will explain far better than any 
language that I can command. 
In this process of vegetable production, we notice certain 
physical conditions that are essential. 1. There is a certain 
condition of the soil that is adapted to the nature of the plant. 
What this condition of the soil is, we know by observation 
and experience. 2. Heat, or a certain degree or range of tem¬ 
perature. What this degree, or range of temperature is, we 
have found out also by experience, and we look for vegetable 
productions accordingly. 3. Water in a humid condition of 
the atmosphere or in the form of rain, or applied by irrigation. 
Other minor conditions there may be, but these are essential. 
Along lines where these combine in certain proportions, we 
find productive zones of vegetation ; where they do not, we 
find barren wastes. Thus the relation of vegetable products 
to well defined and unchangable physical conditions is so plain 
and simple that nobody doubts it. 
In mineral strata and mineral veins, we find evidences of 
the same elements entering into and governing the physical 
conditions of the mineral kingdom. The experience of mining 
has demonstrated the fact that the deposition of ore in the fis¬ 
sure depends as much on certain conditions of the rock, as the 
vegetation of a plant does on a certain condition of the soil. 
The miner looks just as much to these conditions of the rock 
for the metals and their ores as the farmer does to the condi¬ 
tion of the soil for his plants. And we hear the miner talk 
just as much about mineral-bearing rock, as we do the farmer 
about productive and barren soil. 
In the formation and filling of mineral veins we recognize 
(and that very distinctly too) heat as one of the most efficient 
agencies. Nor can we possibly explain the phenomena of 
