SAWMILLS. 487 



H is an iron fly-wheel which regulates the motion of the 

 machinery. 



As soon as the butt has been sawn through its entire length, 

 the butt-carriage is pushed back as far as it will go, and the 

 butt adjusted for a second cut and so on, till it has been 

 completely sawn into planks. 



Recently, many forest sawmills have been improved* in 

 various ways; some of them, however, are still sadly wanting 

 in this respect. The improvements are directed mainly to 

 improving the outturn of sawmills, both in quantity and 

 quality. The most important of these are the material of 

 which the machinery is constructed ; the mode of suspending 

 the saw-blade ; its form and the nature of the teeth (their 

 thickness, shape and set) ; the movement of the carriage and 

 the mode of fastening the butt on to it ; the rapidity of the 

 saw, etc. Besides these points there are several others, so 

 that evidently there are at present many different kinds of 

 sawmills. 



An efficient sawmill should utilise all the available water- 

 power, should yield a sufficiently large outturn of planks, the 

 latter being clean-cut; there should also be little waste of 

 wood and economical working should be ensured. 



2. Material /W. 



If all the parts of a sawmill are constructed of wood, they 

 must be very massive and hence require considerable motive 

 power; much friction is thus caused. The more, therefore, 

 iron is used instead of wood, the less these inconveniences are 

 felt ; on this account, the saw-frame and the guides between 

 which it slides as well as the wheels and driving mechanism 

 are made of iron in all new sawmills. 



3. Mode of Suspension of the Sate. 



As a rule, there is considerable resistance offered to the 

 down passage of the saw-blade by the butt. If the saw is 



* See W. Kankelwitz, " Der Betrieb cler Sagemiihlen," Berlin bei Gartner, 

 iM'iL': .1. I). Dominikus, ' Das illustrirte Handbuch fiir Siigemiiller und Hand- 

 Bager," Remacheid-Vieringhacuen, 1889-90, 2nd ed., is'.H. 



