HARDWOOD RECORD 



33 



ovev-burdeued drykilii to get it in condition; and the latter oan 

 get stock through and ready for finishing so much more rapidly 

 that an appreciably larger amount of lumber would be handled. 

 Since the consumer referred to does no air-drying of his own, he 

 must use his kiln properly if he is not to spoil his lumber; so that 

 the accurate methods required where dressed stock is dried would 

 fit well into the demands of the situation. 



Allowance would have to be made in drying for the shrinkage 

 caused from this iirocess; but as this is known pretty accurately, 

 there would not be such difficulty here as sanding would not take 

 care of. As stated, the general idea looks as if it had possibilities, 

 and the only question is whether the practical difficulties in the 

 way of its adoption are not too great. The plan is at all events 

 worth considering. 



'.v:>? TOaMims^:i^wx<^aim^miii»Jiwwiii^^ 



Cell Structure of Oak and Gum 



There are so many species of oaks described botanically, and there 

 is such a myriad of common names applied to each species locally, 

 that the proper identification and classification of oak lumber is 

 practically an impossibility, except by the most expert. All the 

 oaks, however, can be grouped broadly under two headings, each 

 fairly easy to distinguish. The method of identification is based on 

 the arrangement of the pores in the two groups, and is one wliich 

 can be readily applied by anyone who is fairly familiar with lumber ,with 

 the aid of an ordinary hand-glass. Broadly speaking, there are two 

 groups of oaks described from wood characteristics, namely, the 

 white oak and the red or black oak. Under each one of these is a 

 vast number of species growing in the different localities. In fact 

 the variations in the same species, growing in different sections 

 under different soils and topographical conditions, are so marked as 

 to be decidedly confusing to anyone but the expert. However, for 

 practical purposes the classification mentioned, namely, the grouping 

 under either red or white oak, is all that is necessary commercially, 

 as all oak lumber is sold under one of these headings. Therefore 

 this article will attempt to show fundamental differences in the 

 structure of the two groups. 



The accompanying photographs illustrate three kinds of wood — 

 white oak, red oak and red gum, in the order named. The photo- 

 graphs are enlarged by fifty diameters by what is known as photo- 

 mieography. The specimens'were taken from typical species of the 

 different groups; quercus alba, the real white oak; quercus rubra, 

 the real red oak, and liquidamber styraciflua, the red gum. Before 

 showing the essential differences, it would perliaps be well to explain 

 the structure as shown in the accompanying photographs. 



The picture on the left is the white oak. In it will be seen three 

 large openings apjiarently more or less broken, surrounded by in- 

 numerable cells of imiform size. Just below the two largest of these 

 openings will be seen a dark irregular line, below which appear 

 numerous smaller openings scattered fairly evenly in the wood. On 

 the right of the circle is shown a darker section, apparently made 

 of lines running vertically in the picture. The same characteristics 

 can be seen in the second picture, the red oak, in which the three 

 large openings are apparently free, while the smaller openings are 



much less numerous, less crowded and apparently of a larger size 

 than the same openings in the white oak. The dark section appears 

 on the left of this circle. 



The three large openings in each section are in what is known as 

 the spring wood. This is the section of growth of the tree, which 

 is put on during the fast development in the spring months. At 

 this time there is an active movement of sap, which requires larger 

 vessels to carry it. These large pores form a distinct ring that 

 gradually becomes smaller, running into what is known as the sum- 

 mer wood, which is shown in the bottom of each circle. Here are 

 found distinct pores of smaller size which run up to the dark line 

 running across each picture, known as the annual ring. These lines 

 form the line of demarkation of the year's growth. The dark, ap- 

 pai'ently solid streaks on the right side of the white oak and on the 

 left side of the red oak section, are what are botanically known as 

 the pith or medullary rays. They are what form the splash or 

 figure in quartered oak. 



The two groups of oaks can be readily distinguished by the manner 

 in which the small pores in the summer wood are distributed. In the 

 white oak, as will be seen at the left, the pores are very fine and 

 numerous and crowded in the outer part of the summer wood. Con- 

 sidering that the center of the log from which this cross section is 

 taken lies well below the picture as it appears herewith, it will be 

 seen that the outer part of the summer wood is directly below the 

 dark line running across the circle. As will be seen in the other 

 cut, the pores in the summer wood of the black or red oak are larger, 

 fewer 'in nrunber, and mostly isolated. Another essential difference 

 in the structure of the two groups is in the length of the segments of 

 the pores. In other words, a thin cross section of I'ed oak would 

 admit of the free passage of air or moisture through it. This is 

 readily seen from the large pores which apparently are entirely un- 

 obstructed in the red oak. A cross section of white oak of equal 

 thickness would probably be marked by a considerable obstruction of 

 the pores. This can be seen plainly in the cut to the left, repre- 

 senting the typical white oak cross section. It is common knowledge 

 that, generally speaking, red oak lumber is more porous than white 

 oak lumber. This is attributable to the two facts mentioned, namely. 



WHITE OAK (.QUERCnS ALBA) 



RED OAK (QUERCVS RUBRA) 

 CROSS SECTIONS MAGNIFIED FIFTY DIAMETERS 



KED GUM (LIQUIDAMBAR STYRACIFLVA) 



