226 Double Cross-Grain 



Preliminary Investigations. 



As the edges of the boards had not been trimmed off except in 

 Albizzia procera, it was an easy matter to assemble the boards and 

 examine the grain on the reconstructed drums. 



The species could be separated into two groups according to the 

 grain shown on the surface of the drums but it was impossible to say 

 how far this grouping would hold good for complete trunks. 



I. Grain of uniform inclination. 



Garuga pinnafa came under this heading with a left-handed spiral 

 grain. 



Albizzia procera, as far as could be judged, also came under this 

 heading with a straight grain. 



CalopJiyllum sp. (Poon). An examination of a six-foot beam sug- 

 gested that Poon should be included in this group. 



II. Grain of variable inclination. 



On the surface of some sectors of a drum the grain might be straight, 

 on others inclined as a right-handed or left-handed spiral and again on 

 others the grain might have a sinuous or serpentine course. The general 

 direction of the grain where it was serpentine was either parallel or 

 inclined to the axis of the trunk. Unlike the other group, there was no 

 transverse level where the grain was uniformly inclined around the 

 circumference. 



All the remaining eighteen species came into this group, differing 

 from each other in the degree of inclination shown by the grain and in 

 the length of the undulations where the grain was serpentine. The drums 

 were too short to find the average length of the undulations in the different 

 species. The shortest undulations seen measured between six inches and 

 a foot in length. 



Each species had next to be tested for the occurrence of cross-grain-, 

 which could readily be demonstrated by taking a narrow stick sawn 

 transversely off the end of a radial board and splitting it radially down 

 the centre. 



The fracture on the transverse surface under the edge of the splitting 

 instrument will naturally be straight but the fracture on the transverse 

 surface, the reverse to the one struck, will be sinuous, the departures from 

 the straight conforming to the variations in the inclination of the grain 

 since the plane of fracture follows the inclination of the grain. 



A radial stick from each species was treated in this manner and direct 



