1 6 TWO NEW WORLDS 



to be denser in the infra- world than in our world. 

 Now, the mass of the earth is approximately 10 28 

 grammes, whereas that of an electron is about 10~ 27 

 grammes. The ratio is 10 55 , so that in this case the 

 mass is only reduced by that ratio, while the volume 

 is reduced 10 86 times. This means that the density 

 is increased nearly a billion times. 



This is nothing to be surprised at, and becomes 

 inevitable when we consider that our densities 

 are determined by measurements and estimates 

 made in the case of solid " bodies," consisting, as 

 every one now admits, of discrete particles separated 

 by more or less wide intervals. These intervals 

 are usually imperceptibly small. Solid copper 

 consists of atoms and atomic aggregates tightly 

 packed as close as they will go at a given tem- 

 perature. But this does not mean that the atoms 

 are always in contact. It only implies that when 

 the atoms are pressed together still more tightly 

 forces are brought into play internal kinetic 

 forces most likely which resist any further dimi- 

 nution of volume. An atom may, for all that, re- 

 semble a swarm of bees, which cannot be compressed 

 with impunity. 



Still, the atom has a certain mass, and this must 

 be inherent in its constituents that is to say, the 

 electrons or other particles of which it is composed. 

 If these are, as we have found, a billion times 

 more dense than ordinary matter, it follows that 



