BIRCH 



are very much darker, i.e. the converse of the transverse section. 

 Pores, light coloured lines. Rays, exceptionally broad flakes. 

 Rings imperceptible, as is also the soft-tissue, except as continua- 

 tions and linings to the pores. 



Tangential Section. As the Radial, but the larger rays are 

 broad, spindle-shaped, red stripes, sometimes several inches high. 

 Plate XXI. Fig. 173. 



Type specimens authenticated by F. M. Bailey, and also from 

 commercial sources. 



No. 188. BIRCH. Betula alba. Linn. 



Plate XIV. Fig. 119. 



Natural Order. Cupuliferae. 



Synonyms. B. lenta, Duroi. B. verrucosa, Ehrh. B. pen- 

 dula, Roth., and many others of no interest here. The B. lenta, 

 Linn., is the B. nigra, Duroi. 



Alternative Names. Silver Birch, Black Birch (var. nigra). 

 Russian Maple and Russian Birch (48). 



Sources of Supply. Northern Europe, Asia and America. 



Physical Characters, etc. Recorded dry-weight 32-48 lbs. per 

 cu. ft. Hardness Grade 7, soft, compare Deal : the black variety 

 rather harder. Smell and taste none. Burns well with long 

 lively flame and little smoke. Solution colourless. 



Grain. Very fine, close and even. Surface smooth with 

 satiny lustre. " As though strewn with meal " (86). 



Bark. Shining, laminated, peeling off in curling bands. Len- 

 ticels very large and laterally extended : white or silvery when 

 young or purple-brown or black : deeply fissured and corky when 

 old and at the butt. The transverse section shows numerous 

 whitish, hard, ray-like bodies. 



Uses, etc. Turnery, pit props, put-logs. " Ladders, sabots, 

 hoops . . . shrinks 15-20% of its bulk when green . . . rapidly 

 decays under exposure . . . Moderately durable " (69). Very 

 perishable if young, especially when not scotched (i.e. scored 

 through the bark). Sometimes fails to stand a voyage of a few 

 weeks. 



Authorities. Hartig (42), pp. 41, 32. Schwartz (106), p. 484, 

 plate 2. Nordlinger (187), p. 513. Ditto (86), vol. iii. pp. 47-48. 

 Royle in Holtzapffel (48). Mathieu (69). Wiesner (113), L. 12, 

 p. 886. 



Colour. White : yellowish-white : reddish white. A sap- 

 wood tree, no heart. 



Anatomical Characters. Transverse section : — 



Pores. Need lens, rather fine, size 4, somewhat variable in 

 size : evenly distributed throughout the ring : branched : rather 



215 



