22« FOEESTRY WOEK 



Having fair heating power : Scots Elm, Spruce, Silver 

 Fir, Sweet Chestnut, Cembran Pine. 



Having little heating fower : Weymouth Pine, Lime, 

 Alder, Aspen, Poplar, Willow. 



Hardness in sawing (Gayer). 



Hardest to saw : Poplar, Willow, Lime, Birch, Aspen, 

 Sallow. 



Medium : Oak, Alder, Larch, Maple, and Sycamore. 



Easy to saw : Scots Pine, Spruce, Silver Fir. 



Fissihility (Nisbet). 



Easy to split : Spruce, Silver Fir, Weymouth and Scots 

 Pine, Larch, Alder, Lime. 



Less easy to split: Oak, Beech, Ash, Sweet Chestnut, 

 Austrian Pine. 



Hard to split : Hornbeam, Elm, Sallow, Birch, Maple, 

 Sycamore, Poplar. 



THE USE OF THE SLIDE RULE. 



The slide rule consists of 4 scales — A, B, C, D. 



A and D are fixtures, C and D are on a piece of ivory 

 or wood which shdes in a groove betw^een A and D. 



A, B, and C are marked exactly the same, while D, 

 commonly called the " girt line," is marked differently. 



By the proper manipulation of these 4 scales it is 

 possible to multiply, divide, to square, or extract the 

 square root ; also to find the superficial contents of 

 a board or plank or the contents of timber in the 

 round. 



