398 WISCONSIN STATE AGRICULTURAL SOCIETY. 
we find the same or similar elements. Yet there is a line of 
distinction sharply drawn between these kingdoms, their laws 
and their products, over which the one can never pass to the 
other. 
In the economy of nature, as presented in the vegetable 
kingdom, we find heat and water among the physical condi¬ 
tions necessary to vegetable production. Where these condi¬ 
tions prevail, vegetable productions abound ; where they do 
not, barrenness is the result. Hence the isothermal lines 
bounding the zones of mean annual temperature, and pointing 
out in the vegetable kingdom the comparatively barren and 
productive places. But these physical causes, in their adapta¬ 
tion to the vegetable kingdom, act upon it from above; the 
heat is evidently solar. 
Among the varied and complicated phenomena of the min¬ 
eral kingdom, we notice heat and water playing a very impor¬ 
tant part. In the conditions necessary to the formation and 
filling of mineral veins they seem to be essential. The me¬ 
chanical disturbances of the crust of the earth that produced 
the fissures in which our mineral veins are found are evident¬ 
ly due to some form of heat. The metamorphic rocks, in the 
region of which our most productive mineral formations are 
found, have been changed from their original condition by 
heat. The modifications of other rocks not classed with the 
metamorphic, but more intimately connected with mineral 
veins afford strong evidences of the unequal distribution of 
heat. The ores of every kind, filling our mineral veins and 
other cavities in the rock have evidently been formed by the 
rigid laws of primeval chemistry, the fires of whose laborato¬ 
ries have been fed by internal heat. Thermal waters and boil¬ 
ing springs (the lingering traces of what was once a mighty 
host of physical force) remain to tell us that they had their 
origin in, and received their solvent powers from, heat. The 
systematic grouping of fissures in mineral strata, under the di¬ 
rection of magnetic or electro-magnetic action, is due, 
doubtless, to varying degrees of temperature, or the unequal 
distribution of mineral heat. Indeed, it is difficult to find 
