XXXIV. PIERCIXG PROCESSES 



(a) Piercing comparatively soft stone by simple pressure with a 

 hard, pointed tool, hafted or unhafted, as with an awl or pnnch. 



(7j) Piercing comparatively soft stone with a hard, pointed tool, 

 hafted or unhafted, by twirling under pressure. 



(f) Piercing comparatively soft stone with a hard, pointed tool, 

 hafted or unhafted, by direct percussion, as with a pick. 



(d) Piercing comparatively soft stone with a pointed tool driven 

 by a mallet or hammer. 



THE needle, awl, pmich, and pick penetrate by direct pressure 

 or by direct or indirect percussion. The distinction between 

 the operation of these tools and that of a. drill is that 

 the latter accomplishes its results by the removal of particles how- 

 soever minute, torn from the substance bored, while the piercing im- 

 plement is forced through the substance bored without necessarily 

 removing particles, although portions of the stone may be dislodged. 

 A pointed or edged pick may perforate thus simply, but in its ordi- 

 nary use it crumbles or cuts. 



Piercing implements may be operated by simple direct pressure, 

 by twirling under pressure, or by direct or indirect percussion, the 

 latter implying the use of a driving implement. In general the pierc- 

 ing implement is of harder material than the stone pierced, but a 

 thorn or a pointed bone may be made to penetrate soft stone or in- 

 durated clay or sheets of mica. Such implements may pierce but 

 would not be expected to abrade or crumble. 



This process has little value as a shaping agent, its use being con- 

 fined to simple penetration. It is in a sense related to incising, since 

 an edge may penetrate a soft substance without removing particles, 

 the result being an oblong, instead of a round or somewhat round, 

 puncture. 



363 



