146 



Lord Kelvin 



on 



is distance between nearest atoms of the assemblage. The 

 heavy portions of the curves represent the values of w calcu- 

 lated from (7). The light portions of the curves, and their 

 continuations in heavy curves, represent 4<£(#) and 12<j>(x) 

 respectively in each diagram. The point where the light 

 curve passes into the heavy curve in each case corresponds 

 to the least distance between neighbours at which next-nearests 

 are beyond range of mutual force. All the diagrams here 

 reproduced were drawn first on a large scale on squared 

 paper for use in the calculations from (7); which included 

 accurate determinations of the maximum and minimum 

 values of w and the corresponding distances between nearest 

 neighbours in each assemblage. The corresponding densities, 

 given in the last column of the following table of results, 



Law of Force according to Curve 2. 



are calculated by the formula \/2/X 3 for assemblage I., 

 and 2 \/2/\ 3 for assemblage II. ; " density " being in each case 

 number of atoms per cube of the unit of abscissas of the 

 diagram. This unit is (§ 14) equal to the diameter of the 

 atom. For simplicity we assume the atom to be an infinitely 

 hard ball exerting (§ 13) on neighbouring atoms, not in contact 

 with it, repulsion at distance between centres less than f and 

 attraction at any distance between £ and I. 



§ 16. To interpret these results, suppose all the atoms of 

 the assemblage to be subjected to guidance constraining them 



