145-148] Stable and Unstable Configurations 161 
superposed in such a way as to make these areas fit as well as possible. In 
choosing this particular superposition we have in effect assigned values to 
various adjustable constants, and it is necessary to examine what these 
constants are and what values have been assigned to them in fig. 13. 
Unstable configurations. 
Apart from details, the different ways of superposing the two diagrams 
depend in the main on the numerical values of four quantities representing the 
orientation, scale and the two coordinates of any one selected point in one 
diagram relative to the other. 
Atomic Numbers. 
148. As selected point it is convenient to choose the inner fork of the 
junction between the giant branch and the main sequence. Fig. 11 suggests