nS 



C. M. CHILD. 



stage of regulation and in Fig. 10, a, b, c, at a later stage. These 

 figures as well as all my conclusions on this point are based on 



\J 



a 



8 



V 

 a 



c 

 9 



FIGS. 8-10. 



C 



10 



careful and repeated measurements of all pieces, although the dif- 

 ference is sufficiently striking without such aids. 



