14 THE SPECIFIC HEAT OF WOOD. 



Service in three different parts of its range and two sticks from 

 different sources purchased in Madison, Wis., were used. The 

 material showed a variation of from 3 to 20 rings per centimeter 

 and a difference in density of from 0.40 to 0.59. A piece was cut 

 from just above the stump and another from the bole near the 

 crown, and from each of these pieces cylinders were made represent- 

 ing successive positions between the pith and the bark. No branch 

 wood was studied. When the many determinations on Douglas fir 

 showed no consistent variation of specific heat due either to the 

 position of the wood in the bole or to the place where the tree grew 

 it seemed fairly certain that no such variation existed in any species. 

 Nevertheless, three sticks each of red oak and sugar maple were 

 secured from widely separated localities and possibly from different 

 though closely related species. For these, likewise, no difference 

 in specific heat could be detected within the species. Therefore, 

 when the study of other woods was taken up'no attention was paid 

 to the part of the tree from which the cylinders were taken or to the 

 locality whence the wood came. 



RESULTS. 



The chief results of this work are two: First, the mean specific 

 heats of 20 species of wood have been accurately measured over the 

 interval between 106 C. and C.; second, preliminary results have 

 been secured which indicate a great variation of specific heat with 

 temperature. Also an increase of specific heat was encountered 

 which was apparently due to steaming. 



MEAN SPECIFIC HEAT. 



A summary of the determinations of the mean specific heat for 

 each species is given in Table 1, in which the values corrected by the 

 frequency curve (see appendix) are shown in the last column. Results 

 (calculated) for each cylinder of wood are given in Table 5, appendix. 



