Mineralogy and Geology. 107 
ans, the surface would present considerable inequalities. From what 
now known regarding the depth of the ocean, the continents would 
assume that such a surface is perpendicular to gravity. e mean sur- 
face of the solid crust of the earth would not be perpendicular to gravity, 
* if, after the process of solidification had commenced, any extensive changes 
ce. If 
Scag of the plumb-line from its normal position, and some of them 
ch § cat 
The 
tention to 
Il. MINERALOGY AND GEOLOGY. 
eae at Wood’s Mine, Chester Co., Pennsylvania. —In a letter 
r. W ‘ wri 
