sidewalk is practically gone. The massive steel and concrete bridge 
has supplied the strength needed for heavy fast moving vehicles 
and railroad equipment. 
But in many cases the use of wood has remained unchanged. 
The railroad tie has not been replaced despite all efforts. Wood 
pulp for paper manufacture is used in greater quantities than other 
<inds of pulp material, or, for that matter, than all other kinds com- 
bined. Most furniture is still made of wood. Wooden piles, 
poles and posts are still used in large quantities. 
Many instances of replacement of wood can not be considered 
substitution. Large office and apartment buildings, concrete docks, 
steel ships, steel and concrete bridges and concrete sidewalks are 
zssential needs. Materials other than wood are used for such 
purposes because they are better suited. It would be impractical 
0 build a forty story building of wood, or a railroad bridge across 
he Hudson River, or a battleship. 
Still further, there is much substitution which is simply a 
change in wood use. For instance, the use of lumber for packing 
boxes and shipping containers has been reduced through competi- 
tion from fiber boxes and boards, which are usually made of wood 
pulp. Here and in many similar cases one form of wood use has 
-eplaced another. 
On the other hand there are constantly arising new uses for 
wood. The manufacture of automobiles, insignificant 20 years ago, 
now demands tremendous quantities of wood. Radios, phono- 
graphs, pianos, rayon, chemicals, alcohol and fiber products, all 
articles or commodities which are undergoing tremendous growth, 
draw heavily from the forests. Transportation of large articles 
has created heavy demands for crating. Pianos cannot be shipped 
‘n wrapping paper. Recent investigations of the chemical nature 
of wood have opened entirely new fields for its use as a source of 
important chemical compounds. The phenomenal growth in the 
manufacture of paper, originating only 65 years ago, illustrates the 
possibilities which may develop in the manufacture of any one of 
2 number of different commodities. In wood is found the cheapest 
source of cellulose, a material of constantly increasing importance. 
Furthermore many substitutes cannot be used without an 
additional large use of wood. It is estimated that 15 per cent 
of the cost of concrete construction is for lumber for forms, scaf- 
folding and supports. In fact some methods of concrete construc- 
[13]