Ill 



or discnssed later in this work arc but applications of tlit' 

 fundamGntal principles of heat transmission. 2. These 

 princii)les are briefiy discussed under the form of: a) 

 The "Problem of the Wall," in the steady state; b) The 

 ' ' Problem of the Wall, ' ' in the variable state ; c ) The prob- 

 lem of the cooling- body. 3. The fundamental laws are 

 sufficiently well established theoretically and experiment- 

 ally in some simplified conditions, but in the more compli- 

 cated conditions which obtain in nature and in the labora- 

 tory and in which they are supposed to apply, they are not 

 always proven to be applicable. 4. The acceptance of 

 "established" laws without previous analysis of the prin- 

 ciples on wiiich these laws are based led to misinterpreta- 

 tions and omissions. A notion almost ahvays forgotten is, 

 for example, that of "contact conductivity." 



