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THE POPULAR SCIENCE MONTHLY. 



and-down motion, enabling certain of the teeth to cut meat as nippers 

 do. There is also a backward-and-forward motion, producing a saw 

 or file like operation, and there is a lateral or side motion, producing 

 such a result as that of grinding. It is probable that, from observa- 

 tion on the action of the teeth, the " draw cut," so essential to the 

 perfection of tools that really cut, has been suggested. 



Fig. 2. Double-edged Axe of Greenstone. 



Class 3 will comprehend those tools in which rotation is more 

 usual than rectilineal motion. The tools in this class are constructed 

 on principles allied to those in the two former classes. All drilling 

 and borino; tools belong to this class. 



The action of tools with cutting-edges in Class 1, being the most 

 simple, had better be first considered. As axes and adzes belong to 

 this class, and as the structure of habitations probably led our ances- 

 tors to the formation of tools, doubtless that form of cutting-instru- 

 ment which most commended itself to these primitive artificers would 

 be the first to be constructed. Passing by the very early form, we 

 may commence with a consideration of the edge of the axe or adze, 

 when that edge became part of a constructed implement, and not a 

 mere piece of sharp-edged flint. The construction essential to the 

 tool is a handle, or, as it is called, a " helve." The shape of this helve, 

 and the mode in which the head or metal of the axe is attached to it, 

 are well worthy of some preliminary attention. 



Perhaps here may be drawn the distinction between narrow and 

 broad axes and hatchets. Axes are tools to be used with both hands; 

 they have long handles, and may be swung as sledge-hammers. 

 Hatchets are to be used with one hand, have short handles, they are 

 much lighter and thinner than axes, and are employed more in the 

 trimming than in the hewing of timber. Both narrow and broad axes 

 are employed in forestry, the woodman's choice being affected by the 



