WOODY STEMS AS LUMBER 



455 



furnish for building purposes. Although iron is used extensively 



for the framework of modern large buildings, and concrete and 



stone are used for their exteriors, there are many furnishings 



such as doors, closets, and moldings, which are rarely made of 



any substance but wood. In private dwellings wood is almost 



exclusively used for the framework, floors, and corridors. 



Hundreds of common 



articles are made of 



wood. Over thirty 



billion feet of lumber 



have been used yearly 



for the last one hun- 



dred years in the United 



States alone. More than 



three fourths of this 



vast supply has been 



obtained from conifers, 



trees which, like the 



pine, spruce, and cedar 



(Fig. 322), bear cones 



and are usually ever- 



green. The remainder 



has been obtained from 



oak, maple, ash, elm, 



hickory, and other de- 



ciduoUS trees, that is, 



FKJ 





_ Dedduous trees in winter> with an 



evergreen in their midst. 

 trees which, unlike the 



evergreens, lose their leaves at the approach of winter (Fig. 323). 

 A widely used wood in this country is white pine. It is light 

 to handle, is soft to saw and nail, and is very abundant, growing 

 in many regions throughout the country. These characteristics 

 have made it an important commercial product and are respon- 

 sible for its wide use. Oak, another important wood, is strong, 



