242 



INDT^RTRIAL PLANTS 



Fio. 227.— Pnat-nioss (,S'/)A(i(/- 

 n u m cymbifoliuvi, Peat- 

 moss Family, Sphagnacpn'} . 

 14, plant in fniit, i. 15, 

 spore-case, with lid still in 

 place, e. (Kern(^r.) — 

 Plants soft, yellowish 

 green or piiri)Iish; "fruit" 

 dark bro"n'n. Native home, 

 throuffhont the world in 

 bogs and peat swamps. 



less needful than clothing. Both 

 materials serve us mainly bj- their 

 mechanical strength, l)ut with this 

 difference, that whereas a fibe.r of- 

 fers l)ut little resistance except to 

 stretching, a piece of wood main- 

 tains its form but little changed 

 against severe m(>chanical strains 

 of wliatever sort. Hence the great 

 use of wood for su])port in struc- 

 tures for shelt(>r, storage, transpor- 

 tation, and repose; and its wide 

 ap])lication to innumerable minor 

 uses. The rc^ady separation of 

 vegetable fibers and the facilitj' 

 witii which they may be twisted 

 and interlaced is matched by the 

 comjiarative ease with which wood 

 may l5(> shajied and joined. 



The great importance of tlie 

 •wood-working tratles, carpentry, 

 joinery, turnery, and carving in- 

 dicates something of the extent 

 of our dependence upon the ma- 

 terial in which they work. A 

 further idea of the usefulness of 

 this niaterial may l^e gained from 

 a brief review of the more impor- 

 tant classes of things which are 

 made wholly or in ]3art of wood, 

 and oi the qualities they especially 

 re(iuire in the material used. 



Biiilrlings require (liffer(>nt qual- 

 ities in the frame, the exterior and 

 the interior finish. Strength, ease 

 of working, and availability in 

 large dimensions are the main 

 needs for the framing timbers; re- 

 sistaiic(> to weather or adaptability 



