Figure 27-5. Contour map of log (x 2 -f- z 2 ) = log r 2 with outlines of cylinder in two 

 positions. 



Tabulating the values of log(% 2 + z 2 ) at the points on the periphery of 

 the cylinder indicated by dots, we get 



for point above 

 cylinder 



2.77 



2.74 



2.69 



2.56 

 -1.94 

 -1.67 

 -1.48 

 -1.40 



4.27 X 2 = 8.54 

 The attraction component A g at the two points is then 



A z = 6.67 X 10- 8 X 1 X 8.54 X 2500 

 = 1.42 milligals 



A z = 6.67 X 10" 8 X 1 X 6.02 X 2500 

 = 1.00 milligals 



592 



