Geology and Natural History. 479 
balances this centrifugal force must be equally enormous. ‘Then 
if this perfect fluid outside the vortex-atom can exert this enor- 
_™mous force on the revolving material without being itself pos- 
“petal of motion, then there doe S not seem = be any necessity 
void would be formed in wee which is impossible in a liquid that 
already occupies all space.” The incompressibility of the sur- 
rounding fluid s surely cannot be a reason why portions of the 
prevent portions of the.revolving atom from flying away, it would 
equally prevent the whole atom from doing so, but ac hing to 
motion of the atom. _ When une atom moves it is assumed that 
i; GEOLOGY AND NATURAL HIsTorRY. 
ba ted a the emai Lode and the Washoe District ‘ 
by Grorce F. , U. 8. Geological Survey, CLarE NCE 
Kina, Dircosk: ons oe ; Ato, with many plates, and an Atlas of 
21 sheets in double folio, containing maps and underground sec- 
tions of the region—Mr. Becker’s Report, after some introduc- 
tory sac treats exclusively of the geology of the Co mstock | 
lode, and is a work of great value. Some’ of its facts and results 
are here riety presen nted. 
000,007 
The rocks of” the region (arranging them gone. - the pre- 
dominant feldspar in their constitution as made out by Mr. 
ecker) are as follows 
(1) Having nie _Feldapar portion chiefly orthoclase: Granit 
small area near the Red Jacket mine; guartz porphyry {ace 
of Zirkel), having a oo fluidal aes Se ing 
