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AMERICAN MUSEUM GUIDE LEAFLETS 



lumber). In a cut downward through a loo- some distance out* from the 

 ccnicr. the saw continually strikes and cuts through the -doping walls of 

 uimmI ((incs and the resulting board shows in its midline wood bands ap- 

 pearing as concentric angles or U-shaped figures (Figs. 12 an I 13, tangential 

 or bastard cut of lumber). The U-shaped marks may be the result also of 

 irregularity in the growth of the tree due to the effects of sun, prevailing wind 

 or niher external agency. Occasionally the wood cylinders for some un- 

 known reason have Huted walls, in which case it is easy to see how a hoard 

 gains the appearance called "l>ird*s eye," illustrated in hard maple (Fig. 14). 





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FIG- 15. BLACK ASH BURL 



Irregularity of the wood cylinders in hurls or knots causes the unusual and often 

 very beautiful effects seen in hurl veneers 



