Dixon — Mahogany, Recognition of some Different Kinds. 435 



tissue are empty, or they may be dark, approaching black, when spaces in 

 these laminae are filled with dark deposit. As these laminae form somewhat 

 irregular cylindrical layers in the wood, in tangential sections they appear as 

 irregular linear or thin band-like markings. 



But in all woods recognized as mahoganies, even those devoid of year- 

 rings and the parenchymatous laminae just mentioned, the most striking and 

 beautiful feature of the figuring is the wonderful play of light and shade over 

 a polished longitudinal surface of the wood. This is generally most notice- 

 able on radial surfaces (quarter cuts). When viewed from any one j>oint the 

 radial surface appears to be made up of alternate bands of light and dark, 

 which not infrequently grade longitudinally and transversely into one another. 

 When the piece of wood is turned end for end, or the observer changes his 

 point of view, the bands which were light become dark and vice versa. On 

 tangential surfaces the play of light and shade is not always so contrasted, 

 but yet adds very materially to the beauty of the figure. This characteristic, 

 which is called "roe" or "roeyness," is described by Chaloner and Fleming (3) 

 in West Indian mahogany, but appears to receive little attention as a 

 diagnostic of mahogany from more recent writers. 



Examination into the cause of this effect shows that it is due to the 

 reflection of the light from the fibres of the wood. These are not all strictly 

 parallel to one another in the wood, but are laid down in zones or layers, the 

 fibres of one zone being inclined more or less to those of the adjacent zones. 

 The longitudinal trend of the fibres and vessels in these zones follows a some- 

 what undulatory course, so that the reflection of the light from a given zone 

 may alter gradually on any surface. The orientation of the fibres and vessels 

 in any zone may be observed to change gradually in a more or less neutral 

 region separating the zones. Sometimes the transition is comparatively 

 abrupt. 



The inclination or crossing of the fibres of the different zones is also 

 responsible for another general characteristic of mahogany. A longitudinal 

 surface, when planed, tends to become smooth and rough in alternate bands. 

 This effect again is more marked on surfaces the more they approximate to 

 radial sections. It is also very noticeable on other surfaces where the normal 

 longitudinal run of the fibres has been disturbed by the contortion of the 

 tree or the emergence of a branch. The effect is due to the fact that the 

 zones of fibres pointing obliquely out of the surface, in the direction of 

 motion of the plane, cut smoothly, while the zones of those dipping inwards 

 remain rough. This feature is usually described by wood- workers as a 

 difficulty in "cleaning." 



The characteristic orientation of the fibres of the different zones, crossing 



