I 
64 Dr. Brewster on new properties of heat, 
In every case the number of fringes in these sets increased 
and diminished with the number in the first exterior set. 
Their breadth also varied with the breadth of the fringes of 
the first exterior set, and consequently depended on the law 
of the decrease of temperature in that part of the glass. 
Scholium. 
The truth contained in the preceding Proposition, will, I 
have no doubt, be regarded by philosophers, as one of the 
most extraordinary in physics. The production of a crystalline 
structure in the part of the glass adjacent to the heated iron, 
though a curious property of radiant heat, is in no respect 
hostile to our established notions. But the communication of 
the same structure to the remote edge of the glass, where 
there is no sensible heat, and where the corpuscular forces, 
by which the particles cohere, are not weakened by any ap- 
proximation to fluidity, and the existence of an opposite struc- 
ture in the middle of the glass, developing itself on both sides 
from a central line, are results to which we can find nothing 
analogous, but in the perplexing phenomena of magnetica! 
and electrical polarity. 
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