272 THE REIGN OF LAW. 



ing a fine and open network spread over the sur- 

 face which they cover and protect. These feathers 

 cover the orifice of the ear, and are called the 

 auriculars. They are correlated with the curious 

 passages, the finely hung clapper-bones, and all the 

 elaborate mechanism of that organ. Such are the 

 Internal Correlations. But they are intelligible 

 only when considered in the light shed by other 

 correlations which are external. The wing feathers 

 with close, continuous webs are correlated to the 

 laws by which the passage of air may be prevented 

 — the auricular feathers, with open unconnected 

 webs, are correlated to the laws by which the 

 passage of sound may be rendered easy. The 

 one set of feathers are adapted to the active 

 function of evoking and resisting atmospheric 

 pressure by striking strong, yet light and elastic 

 blows upon the air — the other set of feathers are 

 adapted to the passive function of allowing the 

 free access of the waves of sound into the pas- 

 sages of the ear. These are but a few examples 

 out of millions. Throughout the whole range of 

 Nature the system of Internal Correlation is en- 

 tirely subordinate to the system of External Cor- 



