TOOLS. 



CHAPTER II. 



THE SAW AND ITS VARIETIES. 



Cutting Tools and their working. Structure of the Edge. The Kris. Edge of 

 a Razor. The Sword and the Apple. Australian Saw. Fretwork Saw. 

 Various Saw-flies. The Pioneer's Saw. Cutting Tools of Trichiosoma. 

 Side Teeth of the Saws. The Cordon Saw, or Band Saw. Tooth-ribbon of 

 Whelks, Slugs, and other Molluscs. The Dog-whelk, or Purpura. The 

 Circular Saw. Sawyer-beetles and their Mode of Work. 



STILL keeping to the Cutting Tools and their varieties, we 

 come to the Saw, i.e. the cutting tool set with teeth upon 

 its edge. Now, in plain fact, there is no cutting instrument 

 that does not more or less partake of the character of the Saw ; 

 for, in the first place, it is absolutely impossible for man to 

 grind an edge so fine that, when magnified, it will not appear 

 to be deeply notched, and, in the next place, its cutting powers 

 are greatly due to the notches and teeth, and the direction of 

 their points. 



We will take both these subjects in turn. 



First, as to the notches, or serrated edge. I have now before 

 me two instruments, each the best of their kind, and in both 

 of which the serrations are essential to efficacy. The first is a 

 Malayan dagger, or " kris," and the second is a surgeon's 

 lancet, made by Ferguson, of London. 



In the kris the edge is intentionally serrated, having been 

 eaten away by means of acids until the required effect was 

 produced. The Malayans know by experience that such an 

 edge is most deadly in a weapon, and that it will cut certain 

 vital parts which a smoother edge might pass without doing 

 any damage. 



Now we will take the lancet, and put it under the micro- 



