640 



whitmore. MILITARY GEOLOGY 



[Ch. 34 

 TABLE 



The data above refer to fresh, unweathered rock. 



1 Classes of workability: 1, with shovel and spade; 2, pick and shovel; 3, mattock, crowbar, and iron wedge; 4, com- 

 pressed-air drill and repeated blasting; 5, compressed-air drill and continuous blasting, together with crowbar, iron 

 wedge, chisel, spade, and pick. 



