542 Wisconsin Academy of ScienceSj Arts, and Letters. 



In the following table are given tlie conductivities and densi- 

 ties of the twelve woods examined : 



The results of the work seem to indicate that the law of pro- 

 portionalitv between heat conductivity and density, as an- 

 nounced by De la Rive and De Candolle is at least very approxi- 

 mately obeyed. It is true that in our results slight exceptions 

 to this are shown but it is quite |X)ssible that all the variations 

 obsei'ved are due to errors of obser\^ation. It seems more prob- 

 able, how^ever, that slight variations really do exist, as the dif- 

 ference in form of the cells in different woods must produce a 

 difference in the distribution of material which w^ould in itself, 

 at least in some degree, affect the conductivity. 



The University of ^Yisconsin, December, 1900. 



