434 Scientific Proceedings, Royal Dublin Society. 



This last course is the one naturally essayed by each person who has to 

 deal with mahoganies, and more or less accurate working definitions on these 

 lines have been arrived at. 



J. C. Taylor, in Veneers, Indianapolis, quoted in the " Timber Trades 

 Journal," July, 1917, furnishes an example of a trade description of maho- 

 gany: "There is much difference in texture as well as much difference in 

 appearance between various woods classed as mahogany. There are really 

 just two strong points of value to mahogany. One is the beauty of its 

 appearance, distinguished by various shades of reddish colour and many 

 different figurings. The other point of value is that it seasons readily, and 

 is but little disposed to shrink or warp. To the general public, and for 

 that matter to the majority of wood-workers, mahogany is a reddish wood, 

 and generally with some figure, and often with distinct figure, and fairly 

 characteristic texture, and valued in proportion to the appeal in the figure 

 appearing." 



But such a definition as the preceding is evidently not sufficiently 

 exclusive, for according to it we should have to receive as mahogany any 

 piece of sound wood of a reddish colour, and displaying some figure ; and in 

 such a category a vast number of timbers would be included which no one 

 would for a moment regard as any kind of mahogany. Evidently such a 

 definition must be considerably narrowed. 



In the first place, reddish colour is essential in a wood which is to be con- 

 sidered a mahogany. Keddish colour, of varying tints, is characteristic of 

 the true or original mahogany derived from Sivielenia mahagoni, and is, as is 

 well known, a character generally sought for in mahogany, so that it will be 

 right to include this character in a definition of the wood. This will lead to 

 the exclusion of several white and yellowish woods which have been styled 

 mahoganies, without any defined or substantial resemblance to the original 

 mahogany in physical properties or in minute structure. 



The presence of figure is emphasized in most of the diagnoses of the 

 original mahogany : cf. that of Ohaloner and Fleming (o), Boulger (2), &e , and 

 is generally demanded, as Taylor's (19) description, quoted above, shows, in 

 wood purchased as mahogany. Furthermore, any extended examination of 

 samples of woods emanating from commercial sources as mahoganies 

 impresses on one the feeling that this is an important characteristic of the 

 wood. 



In those mahoganies where year-rings or any form of zonation is present, 

 figure is of course very noticeable on tangential surfaces, and it is often 

 enhanced by the presence of laminae of parenchyma (or soft tissue) in certain 

 regions of the zones. These laminae may be light when the cells of the soft 



