248 Amma Mimdi. 



as to look at the pyramids of Egypt without 

 enquiring whence they came. 



" How then are those salt pyramids built up ? Guided 

 by analogy, you may, if you like, suppose that, swarming 

 among the constituent molecules of the salt, there is an 

 invisible population, controlled and coerced by some 

 invisible master, and placing the atomic blocks in their 

 position. This however is not the scientific idea, nor do 

 I think your good sense would accept it as a likely one. 

 The scientific idea is, that the molecules act upon each 

 other without the intervention of slave labour ; that they 

 attract each other and repel each other at certain definite 

 points or poles, and in certain definite directions, and 

 that the pyramidal form is the result of this play of at- 

 traction and repulsion. While then the blocks of Egypt 

 were laid down by a power external to themselves, these 

 molecular blocks of salt are self-posited, being fixed in 

 their places by the forces with which they act upon each 

 other." 1 



On this very pertinent analogy it is to be 

 remarked that Professor Tyndall has specified 

 only the points on which it holds good ; and 

 here his opponents are in perfect accord with 

 himself. The only point in respect of which 

 they differ from him is that which he has 

 omitted to notice ; and in that point the ana- 

 logy entirely fails. 



When, for the slave-labour employed in the 

 construction of the pyramids, we have sub- 



1 "Fragments of Science," pp. 114, 115. 



