288 APPENDIX 



temperature (dimensions) than &, which is taken to be 

 of the average temperature of the gaseous molecules 

 immediately surrounding the surface of the solid and 

 liquid parts of the world the habitat of man. 



The cause of the decrease of volume of the latter is 

 the pressure of the molecules lying above them the 

 pressure being in all directions, makes the molecular 

 volume approximately uniform. 



Now, if we take air on the surface of the earth, and 

 remove this superincumbent pressure and this we 

 can do by the exhausting air-pump we can cause the 

 molecules to swell until they become of the maximum 

 dimensions (a). As they become larger or of greater 

 temperature they absorb Ether, and a current of Ether 

 flows to them. Conversely, if we take air molecules on 

 the surface of the earth or of the dimensions of b, and 

 press them together, as we can by means of a condensing 

 pump, the molecules become smaller in volume (i.e. 

 temperature) and we press Ether out of them, and a 

 current of Ether flows from them. 



It follows, from this view of our atmosphere, that 

 the upper layers consist of molecules of the maximum 

 dimensions moving with little restraint and in the 

 freest manner. 1 



If we could get out of the atmosphere and look upon 

 it as we can look upon the surface of the ocean, we 

 would, probably, be astounded at the vast waves and 

 the great molecular motion existing on the surface of 



1 This explains the reactions found in the radiometer. It is the 

 freedom of action of the air molecules in the apparatus which moves 

 the vanes. The vacuum must not be perfect or nearly perfect ; for if 

 this were the case, no molecules, or not a sufficient number would 

 exist in the apparatus to move the vanes. 



