IV.] 



HEART-SHAKE. 



55 



persons, not professionally educated to the work, might 

 look at a log without suspecting its presence. Others, 

 again, if they did discover it, would hardly consider 

 it to be of any import- 

 ance, as it is often so 

 small that the blade of a 

 penknife could scarcely 

 be thrust into it. 



There are, however, 

 several varieties of tim- 

 ber which have it, not 

 in an insignificant form 

 or shape, but extend- 

 ing from the pith to a 

 distance of about two- 

 thirds the semi - dia- 

 meter of the tree. This is of serious consequence to 

 the converter who has to deal with it, as the defect com- 

 pletely separates the 



FIG. 8a. 



concentric layers into 



segments of circles. 



The simplest form in 



which we find this 



shake (Figs. 8 a and b), 



is that of a straight line 



crossing the pith, and 



taking a direction in 



the same plane through 



the length of the stem. 



It will, however, be 



found in some specimens to have taken a twisting form, 



and on examining the top of the tree, the shake may 



be nearly at right angles to that at the butt-end (Fig. 9). 



This is about the worst form, as it would involve a 



FIG. Sb. 



