310 The Americajt Geologist. May, woo 
account of the high viscosity, be practically inoperative, ex- 
cept where almost unlimited time is available, as in deep-seated 
plutonic masses. This suggestion is advanced tentatively, 
and not with the idea that in this crude form it afifords a com- 
plete explanation of the coarse granite porphyries. 
EDITORIAL COMMENT. 
A White-hot Liquid Earth and Geological Time. 
Discussing this much discussed subject in the Scottish 
Geological Magazine for February, Prof. Jas. Geikie demurs, 
as others have done, to the narrow limits which physicists have 
recently attempted to set to the past ages of the earth's ex- 
istence. "Some thirty-five years ago geologists were in- 
terested to learn from Sir Wm. Thomson that the time which 
has elapsed since the surface of the earth was everywhere 
red hot could not be less than 20 millions or more than 400 mil- 
lions of years." But when this distinguished author in succes- 
sive essays, gradually cut down the time to the lower limit, his 
conclusions clashed with those of his geological brethren. 
Their hopes of a confirmation of their views were blasted and 
they felt totally unable to reconcile their own conclusion with 
those of the mathematical physicist. 
It is not easy, perhaps not possible, to impugn the conclu- 
sions of the mathematical engine. But, to use a military ex- 
pression well known at the present day, the flank of the mathe- 
matician may be turned. In other words, the data from which 
he grinds out his conclusion may be assailed, and this Prof. 
Geikie attempts. 
After review'ing certain other efiforts in the same direction, 
he adduces the calculations of the Rev. O. Fisher, tending to 
show that no legitimate assimiptions of priniccval temperature 
can, by contraction of the matter, be made to yield sufficient 
shortening of the circumference to account for the many miles 
of surface required by the foldings, crushing and over-thrust- 
ing that are known, not in one part of the world only, but in 
many. 
