PRACTICAL HINTS 



cannot' be used by English readers, as his standard woods 

 are all Indian. I have, therefore, used Nordhngers scale, 

 in which the type species are chiefly familiar European 

 woods, and as it embraces a longer and rather more con- 

 venient series. I cannot say that it is at all uniform when 

 tested by accurate means, but I am loath to pile another em- 

 pirical scheme upon those already in existence, without more 

 substantial gain than appears in sight at present. A rough 

 method, not to be despised, as a test for hardness (?), is to try 

 the wood upon the transverse section (across-grain) with the 

 finger nail. The amount of resistance felt, and the depth of 

 the mark made, give a ready and not at all inaccurate means 

 of comparison. . , 



The surface of a wood depends much upon the density and 

 compactness of the wood fibres, and the size of the pores. The 

 " feel " of. a wood is always present amongst our impressions 

 but cannot be gauged. Ebony and Boxwood feel smooth and 

 cold, Spruce feels warm, and one wood called " Kretti," from 

 British Guiana, feels velvety. Of lustre there are many degrees 

 and also several kinds. The pearly lustre of the Spruce, the 

 frosted lustre of the Autumn wood of the Pencil Cedar, when 

 cleft tangentially, the glassy lustre of the Acacia (Robinia), the 

 greasy lustre of the Lignum vitae are familiar instances. It is 

 sometimes difficult, as in the case of the Oak, to determine 

 whether the flakes of the Silver-grain are either dull or 

 lustrous, though the ground-tissue clearly reflects the light. 

 In most species the ground- tissue reflects the most light, and the 

 Silver-grain appears dull by contrast. In Ebony, on the con- 

 trary, this order is reversed, as the Rays or Silver-grain appear 

 bright against the otherwise very dull wood. 



It is jrather a difficult matter to define the term " Grain." 

 Strictly it signifies the fibre of wood, but in this book it is rather 

 a measure of the size of the pores between the fibres than a 

 description of the relative position of the fibres themselves. 

 Open grain (Oak) shows empty pores, while in even grain (Rose- 

 wood) they are filled with a secretion. The Oak is coarse grained 

 and the Beech is fine. 



For the identification of one out of a large number of species 

 a Key, or some other means of classification, is a necessity. In 

 many works of systematic botany a Key is provided in addition 

 to a well- developed scheme based upon the natural relationship 

 of plants. Unfortunately, such Keys as exist at present are of a 

 very limited extent, being confined to special groups or arbitrary 

 lists of woods.- The most serious attempt is that of Nordlinger, 

 already referred to, but the difficulties of using it are very great ; 

 and it is altogether unconvincing. Such a Key can as yet be but 



xxxviii 



