440 Mr Engledow and Mr Udny Yule, The determination, ete. 
expression. The table shews for comparison the values of p and : 
r given by equation (1) and equation (2) respectively, and the 
standard errors of p and of 7 as obtained by the latter method. 
In the first case the two equations give very divergent results, 
the unsuitability of equation (2) for general use being shewn by 
its failure to give a good approximation to the best value of the 
ratio. In this case, no doubt, we must also regard the standard error 
of r (0°56) as of very uncertain validity. The magnitude of the 
standard error of r in the last case—nearly 3 units—again 
emphasises the caution that must be used before attaching — 
importance to the precise values of these high coupling-ratios. 
