232 



Double Cross- Gra in 



The inclination of the grain was said to be right-handed and denoted 

 by the sign "/" in the tables when it passed from the top right-hand 

 corner toward the bottom left-hand corner; when it was inclined in the 

 opposite direction it was said to be left-handed and denoted by the 

 sign L * /*. When the grain was parallel to the reference side BC it was 

 called straight and was represented in the tables by the letter "?>." 



The inclination of the grain might equally well have been calculated 

 with the left-hand side, AD, of the slips as a basis but for 4 the sake of 

 uniformity measurements were made from the right-hand side only. 



The changes in the inclination of the grain along each stick were next 

 plotted diagrammatically in the form of a curve. The rings were plotted 

 along a horizontal line according to their width in centimetres to a 

 scale of 2 to 1. To a scale of 1 mm. to a degree, the inclination of the 

 grain at each ring was plotted in its correct position about the horizontal 



A X 



rr 



I'l i 



D C 



Right handed Straight grain Left handed 



inclination inclination 



f 

 Fig. 2. Method determining the inclination of the grain- 



line, degrees of right-handed inclination being plotted above the line, 

 and degrees of left-handed inclination below the line. When the grain 

 was straight the point was plotted in its correct position on the line 

 itself. 



On joining these points together a curve was obtained which showed 

 at a glance both the inclination of the grain and the rate of change in 

 the inclination of the grain at any ring. 



In order to represent diagrammatically changes in the course of the 

 grain in a radial plane the curves showing the changes in the inclination 

 of the grain along the sticks of the longitudinal series were placed in 

 sequence one above the other. The same procedure was adopted with 

 the curves of the transverse series. On combining the results obtained 

 from the examination of the transverse and longitudinal series of curves 

 a comparatively clear mental picture was obtained in each species 



