4 Lees, Effect of Pressure on Thermal Conductivity. 



The expression for the temperature at any point, which 

 admits of most easy treatment and is quite capable of 

 representing the changes to be dealt with is z/= F+ Ue , 

 where )3 is a small constant and V and U are constants 

 chosen to best represent the observed temperature at any 

 one of the four surfaces of the two discs of material 

 tested. 



A solution of the equation 

 dv dH 



rr^d^^-^'"^ 



where (2^==—' b'^=~^ 

 cp qcp 



c the specific heat, ^the area,/ the perimeter of the 



cross section, k the conductivity, h the emissivity of 



the disc tested, 



which satisfies the conditions, z/= F"o+ C//^'^ when ,r=0, 



z;=Fi+t/'i^' when x=l the thickness of disc, and 



i3>^^ is 



V^ sinh 1- V sinh -l -x 



a " a 



sinh— 

 a 



Ui sinh — -X + U^ sinh ^ . /- 



X 



a 

 At x=l 



^ = U F.coshl /- F„cosech£ / \ 

 dx aV a a J 



a I a a J 



+ . 



di . 1, 



or, smce — is small, 

 a 



Taking the mean value of each observed temperature 



