■2 in; 



VIAAASG AND CdNVKItSlON. 



sharp and retain its set. Saws rolled out of cast steel are best 

 iu these respects. 



As re«i;ards shape, curved saws are {)referahle to straight ones, 

 especially for coniferous wood, and a radius of 5 feet gives the 

 most suitable curvature for general work. 



For practised sawyers, working with a curved saw is less 

 fatiguing, and the motion corresponds better with the movement 

 of the arms than in using straight saws ; the sawyer can also work 

 in a more upright and less cramped position in the former case. 

 "With a curved saw there is also more room for the sawdust 

 and the latter is less hindering to the work, owing to the curva- 

 ture of the saw (fig. 88). It 

 ^'°' ^^' must, however, be admitted that 



the use of curved saws requires 

 more skilled and experienced 

 sawyers than that of the straight 

 saw, for the curved saw is more 

 liable to stick when the blade is 

 not always pushed in the same 

 plane, a difficult thing to do at 

 first. The chief rule is to 

 guide the saw lightly, and use no unnecessary force. 



In the case, therefore, of unskilled sawyers, such as men only 

 occasionally employed in sawing, it is better to restrict them to 

 the use of straight saws. For skilful sawyers, in coniferous 

 forests, the curved saw only should be used. 



As regards the length of saws, there is more risk of the blade 

 bending and buckling (or sticking in the wood), if the saw be too 

 long, while very short saws tire out the sawyers, and cannot be 

 used with large timber. Lengths from 41 to 5 feet, with a 

 breadth of 8i inches without the teeth, are the most effective 

 dimensions for a cross-cut saw. 



As regards tlu; thickness of the blade, all saw s should become 

 gradually thicker away from the edge, lnil the thickness should 

 be only sufficient to prevent too great liability to bend. 



As regards weight, saws should not be too light, or their use 

 becomes very fatiguing, and ;V, lbs. is the best weight. 



The construction of the teeth is of importance, and trian- 

 gular teeth are most eti'eclive ; M tceib, however, give good 



