728 JOURNAL OF FORESTRY 



The following table shows the number of cords of various common 

 woods required to equal one cord of w'ell air-dried hardwood or one 

 ton of coal : 



Cords Cords 



Ash i.io Poplar 1.55 



Basswoocl 1.70 Cedar 2.10 



Beech i.oo Douglas fir 1.20 



Birch 1 . 00 Balsam fir i . 80 



Butternut 1.60 Hemlock 1.60 



Elm 1 . 00 Jack pine 1.50 



Maple 1.00 Spruce 1.60 



Oak, red 0.97 Tamarack i . 15 



Oak, white 0.93 



Another point worth bearing in mind in connection with the burning 

 of wood in place of coal is the difference in the amount of ash pro- 

 duced. A cord of hardwood will make only about 60 pounds of ashes, 

 while a ton of hard coal will make from 200 to 300 pounds; judging 

 from the grade of hard coal coming to Canada during the past winter, 

 191 7-18, the latter amount is more likely, and some lots will run even 

 higher than this, especially the small "steam sizes." The calorific value 

 of these latter may frequently be as low as 10,000 B. T. U. in place of 

 the 13,000 B. T. U. used in the above calculations. 



Canadian Forestry Journal, April, 1918, pp. 1632-3. 



A series of experiments to determine the effect 

 Moisture of moisture re-absorption upon the strength of 



and air-dried timber has recently been concluded in 



Strength the testing materials laboratory of the Massachu- 



of setts Institute of Technology. The series in- 



Tiinher eluded parallel tests upon southern yellow pine 



and Douglas fir. The material tested was ob- 

 tained from 4-inch planks, obtained in the local markets, which were 

 dried in the air to an average moisture content of 6 to 8 per cent. Two 

 inch by 2 inch by 20 inch sections were selected from the planks. Two 

 2 inch by 2 inch by 8 inch test specimens were cut from each of these 

 sections. One 8-inch specimen was immediately tested in an air-dry 

 condition, while the contiguous specimen was allowed to re-absorb 

 moisture before it was placed in the testing machine. This procedure 

 was repeated until a sufficient amount of data was obtained. The speci- 

 mens were allowed to re-absorb moisture either by immersing them in 

 water at 70° F. or by placing them in saturated air at a temperature of 

 120° F. for varying periods of time. 



