Chap. 7] 



GRAVITATIONAL METHODS 



259 



where R is the radius of the cyUnder. Fig. 7-97 illustrates the action of 

 a horizontal cylinder in the form of lines of equal position for a given effect 

 on gradients and curvatures. It is seen that the curvature is insensitive 



H-tih 



X 



.^^0 



:^=^^ 



v\V\\\\V\\ 



^^^:Z. 



^^^ 



J 



(h) 



Fig. 7-98. Two-dimensional bodies: (a) cylinder, (6) slope, (c) symmetrical anti- 

 cline, (d) symmetrical syncline, (e) inclined dike, (/) vertical step, {g) rectangular 

 slab, {h) infinite vertical dike. 



to masses 45° below the horizon and most sensitive to those directly be- 

 neath and in the horizon. The gradients, on the other hand, are insensi- 

 tive to masses in the horizon and directly below, and most sensitive to 



