CLOTHES 



351 



The protective value of clothing mainly depends (1) inversely 

 on the thermal conductivity of the material, (2) on its power of 

 absorbing water, and (3) on the arrangement of the fibres of the 

 material in the cloth. The conductivity of various materials is 

 given in Tables LVI. and LXI. 



TABLE LXI. (FROM RUBNER). 



Substance. 



Air - 



Brown human hair - 

 Grey human hair 

 Feathers (eiderdown) 

 Horse hair 



Cotton cloth (smooth) 

 Woollens - 

 Silk 



Cashmere wool- 

 Cambric 

 Flannel 

 Flannelette 



Coefficient of Conductivity. 



53 x 10~ 6 

 76 x 10- 6 



74 x 10- 6 

 57 x 10- 6 

 57 x 10- 6 

 81 x 10- 6 

 68 x 10- 6 

 68 x 10- 6 

 68 x 10- 6 

 81 x 10- 6 

 72 x 10~ 6 



75 x 10~ 6 



In order to calculate the coefficient of protection of clothing 

 one must know the thickness of the material. Table LXII. 

 compiled by Rubner gives further information regarding the 

 density of the material and of the amount of air enmeshed in the 

 structure. This layer of imprisoned air, as we have already 

 mentioned, has a greater protective value than mere thickness of 

 material. 



TABLE LXII. 



