36 



r.ll I I. TIN 181, U. S. DEPARTMENT OF AGRICULTURE. 



who depend entirely upon it. In only two States — Pennsylvania and 

 Iowa — did the amount spent for coal exceed that spent for wood. In 

 Pennsylvania this was probably due to the ready availability and 

 cheapness of coal; in Iowa, to the relative scarcity of wood. The 

 proportion of wood furnished by the farms on which it was con- 

 sumed is significant. This averaged over 9G per cent, and the remain- 

 der — less than 4 per cent — was probably bought from adjacent farms. 

 In the two Southern States that appear in the table, approximately 

 three-fifths of all the wood was used in fireplaces. The other two- 

 fifths was used in cookstoves. 



The heating value of coal is, of course, much greater than that of 

 wood. Forest Service investigations 1 show that in general 1 pound 

 of coal has a heating value equivalent to 2 pounds of seasoned wood. 

 Allowing 80 cubic feet of solid wood to a standard cord (4- foot sticks 

 in a pile 8 feet long and 4 feet high), the weight of a cord of the 

 heavy, medium, and light woods would be about 4,000, 3,000, and 

 2,000 pounds, respectively, for seasoned sticks containing 15 or 20 

 per cent moisture. Table 12 shows the number of cords of several 

 kinds of seasoned wood that are necessary to give approximately the 

 same heating value as 1 ton of coal. 



Table 12. 



- Amount of wood of different species necessary to gire the heating 

 value of 1 ton of coal. 



1 cord of wood 

 equivalent to 1 

 ton of coal. 



1 '. cords of wood equiv- 

 alent to 1 ton of coal. 



2 cords of wood 

 equivalent to 1 

 ton of coal. 



Iliekory. 



Oak. 



Beech. 



Birch. 



Hard maple. 



Ash. 



Elm. 



Locust. 



Longleaf pine. 



Cherry. 



Shortleaf pine. 

 Western hemlock. 

 Red gum. 

 Douglas fir. 

 Sycamore. 

 Soft maple. 



Cedar. 



Redwood. 



Poplar. 



Catalpa. 



Norway pine. 



Cypress. 



Basswood. 



Spruce. 



White pine. 



There are other factors besides heat value which affect the useful- 

 ness of the different kinds of wood for fuel. Pine, for example, has 

 a relatively low heat value per unit volume, but it ignites readily and 

 gives out a quick, hot flame which soon dies out. This makes it a 

 favorite with rural housekeepers, because it is particularly adapted 

 for hot days in the kitchen. Hickory has the highest heat value, 

 burns evenly, and " holds the heat." Oaks come next in this respect, 

 followed by beech, birch, and maple. In selecting wood for fuel, 

 however, it is important to consider the much greater value which 

 some of the species have for other uses. It is a mistake to burn 



1 " Fuel Value of Wood," by IL S. Betts and Earnest Bateman ; mimeographed circular 

 of the Forest Service, 1913. 



