SAWMILLS. 311 



centre, from which the needs of the landowner and of his 

 tenants can be easily supplied. If the sawmill can con- 

 veniently be put up near the home-farm, it may get the use 

 of an oil-engine, or of a steam-engine which can also be used 

 for the extraction and delivering of timber ; but if the woods 

 are small a traction-engine and a portable saw-bench are generally 

 most economical, while in larger woods a stationary sawing-plant 

 will usually be most suitable. 



Estate sawmills of small size are worked cheaper by water- 

 power than by steam, although the latter works quicker and can 

 turn out a much larger supply of converted timber (Figs. 85-87) ; 

 but it is only when steam is used that slabs, tops, and butts, &c., 

 can be converted into railway-keys, small staves, and box-boards, 

 or sold as firewood, or used for preparing oxalate of lime (for 

 oxalic acid) and acetate of lime (for acetic acid), or for making 

 wood-wool, or using the sawdust for litter and manure, &c. 



Where the timber has only to be conveyed for 2 to 3 miles 

 a stationary sawmill is the more economical, but for long 

 haulage, the use of a traction-engine and a portable saw-bench 

 usually pays best. 



Sometimes the machinery of stationary sawmills is driven 

 by turbines or horizontal water-wheels, which utilise a small 

 water-supply very well, but require a high fall of water. The 

 simplest and oldest form of water-wheel was the over-shot 

 vertical wheel, worked by the force of a good volume of water 

 having a low fall. The impetus thus given was conveyed to 

 an inner wheel, at the end of the axle of which was a revolving 

 crank with a movable lever attached (pitman), fastened at its 

 upper end to the bottom of a framework (gate) to which a 

 single vertical saw was attached, running in grooves between 

 two stout posts. At each turn of the water-wheel the crank 

 revolved and alternately raised and lowered the frame-work 

 containing the saw, each downward stroke cutting into the 

 log, and the teeth of the saw being set slightly downwards 



