50 PROPERTIES OF WOOD. 



Soft. Pine, spruce, silver-fir, Cedrela, cypress, lime. 



Very soft. AVey mouth pine, willow, poplar, Paidoivnia, 

 Cunninghamia, Bombax, Leitneiia Florldana (cork-wood from 

 Florida, used for floats for fishing-nets). 



Soft as cork. Herminiem, from the Upper Nile. [Indian 

 solah, generally termed pith, but really the wood of Aescliy- 

 nomene aspera, which grows in marshes ; it is used for hats, 

 fishing-floats, etc. Tr.] 



5. Specific weight. 



A high specific weight in wood is not necessarily a desideratum. 

 On financial grounds, when light wood offers the same advan- 

 tages as heavy wood, the lighter wood is preferred. Wood of 

 a high sp. weight is valuable on account of the other proper- 

 ties that this more or less involves, chiefly hardness and 



(W\ 

 *y] of a piece of wood, of 



which V is the volume and W the weight, is very easily and 

 exactly determined from its absolute weight and volume, for 

 more than a century the determination of the sp. weight of 

 woods has offered a favourite field for investigation. Nearly 

 all investigators, from Duhamel to those of the present time, 

 have decided that the excellence of wood depends on its 

 specific weight. Konig, Hartig, and his scholars, Bertog, 

 Eichhorn, Omeis and Schneider, have considered the term 

 heavy, when applied to wood, as identical with good, from 

 every point of view. Nordlinger, Bauschinger, Schwappach, 

 Fernow, Both and Janka, whose works on the strength of 

 wood will be discussed further on, refer to excellencies depen- 

 dent on high sp. weight. Other authors, such as Tetmajer 

 and H. Mayr, regard sp. weight as only one of the factors in 

 adjudging the strength of species of wood. If it were possible 

 to exclude other factors which affect the strength of wood and 

 often alter it in a way that does not correspond to variations 

 in sp. weight, the latter might be the best factor in the 

 question. But this is impossible, so that the prediction of 

 the strength of a wood from its sp. weight is not more trust- 

 worthy than weather-forecasts based on atmospheric pressure 

 only. Agriculture cannot be directed by the rise and 



