THK WOOD 238 



of both iron and coal are exhaustible ; the ff)rest , under 

 proper management, produces forever. 



2. Wood is cheap ; metals are dear. Even in the form 

 of lumber, and with the cost of long-distance transporta- 

 tion added, wood rarely costs the consumer in this country 

 more than twenty-five cents per cubic foot ; while iron in 

 bars and sheets is worth at wholesale from five to ten 

 dollars per cubic foot. 



3. Wood is soft ; simple tools and small effort sutfice 

 to shape it. Iron is hard ; any change of form, whether 

 by casting, rolling, sawing, cutting, planing, turning, 

 filing, boring, or grinding, requires much labor, or else 

 complicated and costly processes and equipments. In 

 the ease and rapidity with which wood can be shaped, 

 reshaped, and combined in structures, it excels all other 

 materials. 



4. Wood cleaves or splits ; metals do not. While this 

 property has its disadvantages, it is one that in some 

 directions determines the usefulness of wood. It permits 

 ready preparation for fencing and firewood, which latter 

 use exceeds in bulk ten times the amount of iron and 

 steel used in this country. 



5. Wood is stronger than is usually supposed. In 

 tensile strength (pull lengthwise or with the grain of the 

 wood) a bar of hickory exceeds a similar bar of wrought 

 iron of the same length and weight, and it even surpasses 

 steel under the same conditions. 



