THE CHISEL. 233 



Polynesia, and the Steel Adze of this country. We begin with 

 the Chisel. 



All those who have even a slight knowledge of anatomy 

 know how curiously exact is the resemblance of the Chisel of 

 civilised life to the front tooth of any Rodent animal. The 

 head of the Beaver is here given as an example, but the tooth 

 of a mouse, rat, or rabbit, which can easily be obtained, is 

 quite as good an example. These teeth are made after a very 

 beautiful fashion. Their outer surface is covered with a plate 

 of very hard enamel, while the rest of the tooth is of bony 

 matter, and comparatively soft. Consequently, when the tooth 

 is used, the enamel plate forms a sharp edge, while the rest of 

 it is worn away, thus keeping the chisel-like end in its proper 

 form. 



The power of these teeth may be appreciated by any one 

 who has been bitten even bv so small a rodent as a mouse, the 



TOOTH AN'D JAWS OF BEAVEB. 



sharp edges meeting in the flesh, and causing a very painful 

 wound. When the teeth are large, as in the Beaver, and the 

 jaws powerful, their force is something wonderful, tree-trunks 

 of considerable size being cut down quite easily. 



Perhaps some of my readers may not be aware that the 

 Chisel is constructed on exactly the same principle as the tooth 

 of the Rodent animal. It is not entirely made of steel, as is 

 generally thought. In the first place, a valuable material 

 would be needlessly wasted, and, in the next place, the tool 

 would not keep its edge except with infinite labour in grinding. 



The principal part of the Chisel-blade is therefore made of 

 soft iron, a very thin plate of steel running along the back. 

 This plate answers the same purpose as the enamel in the tooth, 

 while the soft iron takes the place of the soft bone. Axe- 

 blades, which are, in fact, formed like two chisels placed back 

 to back, are made on a similar principle, except that the steel 



