314 THE UTILISATION OF WOODLAND PRODUCE. 



angle (Fig. 89) ; frame-saws have J-shaped teeth with cutting 

 points facing downwards (Fig. 90). The thickness or gauge, 12 

 to 16, varies according to kind of wood to be sawn, the smaller 

 gauge or thicker saws being needed for hardwoods and resinous 

 Conifers, and the thinner saws of higher gauge being used for 

 softwoods and non-resinous Conifers ; but the circular saws have, 

 for stability, to be thicker than the vertical frame-saws, and 

 therefore cause more waste in sawdust. For portable estate- 



Fig. 89. 



Fig. 88. 



Teeth, of Frame-Saw. 



Teeth of Circular Saws. 



1. Wide-pitched, strong-hooked teeth of Ripping-saw for soft-woods. 



2. Triangular arrow-shaped teeth of a Cross-cut saw. 



3. Slightly-hooked and less wide-pitched teeth of Ripping-saw for 



hardwoods. 



mills a 10- to 12- horse-power engine with high-pressure boiler 

 and furnace suited for burning waste wood is the most con- 

 venient. It costs about <300-<350, whereas a traction-engine 

 of similar power would cost <500-<550. 



A 12-H.P. engine can drive 4 circular saws (one cross-cutting 

 and 3 ripping-saws), or in all 4 ripping-saws when cross-cutting 

 is finished. 



The speed of circular saws depends of course on the driving- 

 power, and varies greatly in water- and in steam-power mills. 



