31 



suggestion has been made by the writer, and the few observations so 

 far carried out by him tend to support it, that the shape of the buttress 

 is constant for the species. That is to say, in the same species the butt- 

 resses have the same relation of height to base, and the hypotenuse 

 is straight, depressed or curved for the same species, regardless of the 

 actual size of the buttress, which is dependent on telluric conditions. 

 Some species, such as Chlorophora excelsa and a species of Daniella 

 have practically no buttresses ; others such as Eriodendron anfractuo- 

 sum have buttresses to a height of thirty feet, and between these is 

 every gradation. 



When cutting a tree that is buttressed a platform is erected so 

 that it may be cut above the convergence of the buttresses. Stumps 

 often twelve feet high result with much waste of good wood but saving 

 of time to the exploiter. Above the buttresses the trunk runs away a 

 long clean bole often 80 feet high to the first branch, alter which it is 

 broken up into the crown of the tree. 



The following measurements are the average taken in 1912 from a 

 considerable number of " mahogany " trees, Khaya ivorensis. At the 

 present time the average content of an exported log is nearer 80 cubic 

 feet and that of a tree 200 cubic feet. This would appear to be ac- 

 counted for from the pressure of competition and the 1921 high selling 

 prices of mahogany when almost any log was accepted on the local 

 market. Before the War, as a rule, only the largest and the best trees 

 were selected to be cut, whereas nowadays every tree over the pre- 

 scribed minimum girth is likely to be felled. 



Average Measurements of 100 Mature " Mahogany Trees." 



From the above figures it is seen that the bole of the ordinary 

 " Mahogany Tree," Khaya ivorensis, on the Gold Coast, has a taper of 

 nearly 6^ inches in girth for every 10 feet in length, and that the num- 

 ber of cubic feet of timber which was extracted from each of these 

 trees was approximately 453, which gave an average of 181 cubic feet 

 per log. 



It should be mentioned that there is an enormous amount of waste 

 in not extracting the top and branch logs. It is hoped that in the 

 near future this will not be neglected. 



