194 



Mr. C. Davison on the Penodie 



Curves of Resultant Motion. — It will be noticed from the 

 preceding summary that M. Plantamour's discussion of his 

 observations is confined to the components of the motion in 

 two given directions, namely from east to west and from north 

 to south. It may be possible, therefore, to learn something 

 more from his observations by considering the movement 

 which is the resultant of these two components. 



The curves representing the resultant motion of the ground 

 are drawn as follows : — 



The zero of the E. W. level is its position on Oct. 1, 1878 , 



Tiq. I. 



that of the N.S. level is its position on Dec. 23, 1878. The 

 positive abscissae and ordinates of points on the curve represent 



