400 
WISCONSIN STATE AGRICULTURAL SOCIETY. 
The uneducated farmer feels, while moving amid the rich 
unfoldings of vegetable nature, that the heat to which these 
organisms are subjected flows from the sun as its source; while 
the miner, untutored as he may be, in his downward course in 
the mine feels that the increasing temperature he encounters is 
produced by heat arising from some internal source. 
The convictions fastened on my mind in early life by such 
experiences in the deep mines of Cornwall, England, can nev¬ 
er be changed by arguments to the contrary. It may not be 
so easy to convince others who have not been made acquainted 
with such evidences. It is natural for us without them to be¬ 
lieve that the earth beneath our feet is a solid mass of rock. 
But even then, one would suppose that the first shock of an 
earthquake, or the first sight of a volcano in the act of pour¬ 
ing forth its molten lava would unsettle our faith in this, and 
prepare the mind for the reception of any evidence that would 
throw light on their origin. 
The rapid advance of the natural sciences, however, and 
the careful experiments on the increasing temperature down¬ 
wards of our deep mines are fast divesting this question of 
central heat of its hypothetical character, and causing it to be 
regarded as a settled fact. 
The observations of Prof. Palmieri, made during the last 
eruption of Vesuvius, has brought to light the following start¬ 
ling fact, namely, that he noticed on that occasion distinct ti¬ 
dal phenomena, indicating that the moon’s attraction occasioned 
tides in the central zone of molten lava very much as it causes 
them in the ocean. This would leave us to infer that vol¬ 
canic phenomena are connected, at a certain depth beneath the 
surface, with a continuous sea of molten lava or rock. 
Prof. David Forbes, in one of his recent lectures, sums up 
the evidences of deep mining on central heat, in the following 
language: 
“ A numerous set of experiments made in deep mines in various parts of 
tlie'world, often far distant from one another, has conclusively proved that the 
temperature of the earth, at least as deep down from the surface as has been 
explored by man, increases in direct ratio as we descend towards the center. 
