MORE CONCERNING MECHANICAL TOOLS. 175 



sired, but shall enable it to be used with equal facility upon a broad 

 as upon a narrow surface. 



Given a rough piece of timber, nine inches wide and five feet long, 

 to be smoothed by tools guided only by the handicraft skill of the 

 workman, setting aside the adze as dangerous and unsuitable, the 



Fig. 4. 



probability is, that the tools selected would be gouges and chisels of 

 various breadths and curvatures. The order of use would probably 

 be, first, the narrow and deeply-curved gouges, ^^, these to be fol- 

 lowed by the .shallower and broader, , N , these ngain to be followed 



A B 



by the chisels, using in the first place a chisel wider than a b. 



Let us consider what these tools. would respectively accomplish 

 if the timber is rough, as from the axe or pit-saw. The small gouge 

 would corrugate the surface, ww ^--^- the second gouge would en- 

 large the corrugation to this, w^-ww ; and the chisel might render 



Fig. 5. 



these more irregular. Such considerations as these, combined doubt- 

 less with others, led to the designing of what may be generally called 

 the " guide principle," and this has been extended to various branches 

 of artisan labor. At present we are only concerned with the applica- 

 tion of this principle to gouges and chisels. This guide principle 

 may consist of a guide as to the deptli of cut, or as to the form of the 



