4 T. C. CHAM BERLIN 



in the ascending thread of lava, leaving behind the less eutectic 

 substances. They were thus well fitted to fulfil three functions: 

 (i) to flux their way upward, (2) to separate the more fusible 

 material from the less fusible, and (3) to carry the former out to 

 the cold zone or the surface, taking along the chief source of heat 

 and the heat already generated. By thus draining away selectively 

 the more fusible elements in the mixed material and raising the 

 mean resistance of the rest to fusion, they help to maintain the 

 solidity of the main mass. It is obvious that adjacent threads of 

 hot self-heating lava must render one another assistance in mutually 

 uniting and massing their forces for fusing their way outward. 

 After such tracts have been drained of their more fusible substances 

 and the conduits closed, new paths in ground less depleted of its 

 eutectic material would naturally be chosen and thus the selective 

 work should at length cover the whole field and raise its mean 

 fusion-point, while the self-heating radioactive particles were more 

 completely removed. 



At all stages of this selective process it is held that the differ- 

 ential stresses of the earth body lent effective aid in extruding the 

 liquid matter. The great pervasive stresses of the earth, static 

 and dynamic alike, are intensest in the deep interior and graduate 

 outwardly. The differential components of these are well suited to 

 squeeze toward the surface the liquefying portions of the interior 

 matter about as fast as these accumulate in sufficient quantities 

 to respond readily to such stresses, while the liquids themselves 

 readily yield to the rise by reason of their heated state and the 

 gases they gather to themselves. To this doubly facilitated 

 extrusion of liquid matter carrying its special thermal source with 

 it is assigned the function of clearing the depths of their original 

 radioactive substances and of their heat products, with the in- 

 cidental effect of perpetuating the solid state of the earth as 

 a whole. 



If the simile may be pardoned, the I'quid threads may be 

 likened to the sweat pores of an organic body, regulating its temper- 

 ature by a natural perspiratory system. The pools of lava that at 

 times accumulate at the surface function as the sweat drops of the 

 earth body. They seem large, to be sure, in terms of ordinary 



