THE FORMULA 



Both countries may have been affected by some 

 movement from the interior. 



As I shall be constantly using the terms 



(a) Leading names, 



(6) Perpendicular development, 



(c) Complementary parts, 



(d) Lateral development, 



it will be well for my reader clearly to understand 

 what I mean by these terms, and I hope that a glance 

 at the figures below may show my meaning and their 

 position in the formula. 



Leading Names. Three Complementary Parts. 



Perpendicular 

 development 



The Formula. 



Lateral Developments. 



B 2 



