62 TIMBER. 



broad-leaved woods. In coniferous woods they are usually so fine and 

 closely packed that to the casual observer they do not appear. Their 

 breadth and their greater or less distinctness are used as distinguishing 

 marks, being styled fine, broad, distinct, very distinct, conspicuous, and 

 indistinct when no longer visible by the naked (strong) eye. 



(7) Concentric lines, appeariug in the summer wood of certain species 

 more or less distinct, resembling distantly the lines of pores but much 

 finer and not consisting of pores. (See fig. 38.) 



Of microscopic; features, the following only have been referred to: 



(8) Tracheids, a description of which is to be found on page 20. 



(9) Pits, simple and bordered, especially the number of simple pits 

 in the cells of the pith rays, which lead into each of the adjoining 

 tracheids. 



For standards of weight, consult table on page 28; for standards of 

 hardness, table on page 47. 



Unless otherwise stated the color refers always to the fresh cross sec- 

 tion of a piece of dry wood; sometimes distinct kinds of color, some- 

 times only shades, and often only general color effects appear. 



HOW TO USE THE KEY. 



Nobody need expect to be able to use successfully any key for the dis- 

 tinction of woods or of any other class of natural objects without some 

 practice. This is especially true with regard to woods, which are apt to 

 vary much, and when the key is based on such meager general data as the 

 present. The best course to adopt is to supply one's self with a small 

 sample collection of woods, accurately named. Small, polished tablets 

 are of little use for this purpose. The pieces should be large enough, 

 if possible, to include pith and bark, and of sufficient width to permit 

 ready inspection of the cross section. By examining these with the 

 aid of the key, beginning with the better-known woods, one will soon 

 learn to see the features described and to form an idea of the relative 

 standards which the maker of the key had in mind. To aid in this, 

 the accompanying illustrations will be of advantage. When the reader 

 becomes familiar with the key, the work of identifying any given piece 

 will be comparatively easy. The material to be examined must, of 

 course, be suitably prepared. It should be moistened; all cuts should 

 be made with a very sharp knife or razor and be clean and smooth, for 

 a bruised surface reveals but little structure. The most useful cut may 

 be made along one of the edges. Instructive, thin, small sections may 

 be made with a sharp penknife or razor, and when placed on a piece of 

 thin glass, moisteued and covered with another piece of glass, they 

 may be examined by holding them toward the light. 



Finding, on examination with the magnifier, that it contains pores, 

 we know it is not coniferous or nonporous. Finding no pores col- 

 lected in the spring- wood portion of the annual ring, but all scat- 

 tered (diffused) through the ring, we turn at once to the class of "Dif- 



