58 



E. I. Gal'perin et al. 



graphically; for this purpose we construct, along the direction of the normal 

 azimuth, a section of the interface of the vertical plane and drop a perpendicu- 

 lar to the point of incidence (Fig. 6, 6). 



In our problem the azimuth of the normal to the interface for all its 

 points is the same, 90°. This is because all the structure contours are rectilinear 

 and have an azimuth of 0°. The angle of incidence of the normal to 

 the interface is constant at 30° in sectors where the interface is represented 



c b a 



f e d 



(b) 



Fig. 6. Determination of the direction of the normal to the interface, a — determination 

 of the azimuth of the normal at points a, b, c, k, m; b — determination of the angle with 



the vertical. 



by planes, while in those sectors where the interface is represented by 

 a cylindrical surface the angle of incidence of the normal to the vertical 

 varies from to 30°. 



The ray which we are considering which has an azimuth of 70°, strikes the 

 interface at a point which is projected on the plan as point c (Figs. 4 and 5). 

 We place an imaginary centre of the net at the point of incidence and 

 construct on the net the directions of the incident ray ^(70° and 20°) and 

 the normal to the interface (90° and 30°) and then we determine the 

 direction of the reflected ray B (83° and 79°) — Fig. 7. Figure 7 also shows 

 the determination of the reflected ray direction for all the remaining rays 

 of the 20° surface which we are considering. The azimuths of the incident 

 rays are separated from one another by 10° (that is 0°, 10°, 20°, 30°, 40°, 

 50°, 60°, 70°, 80°, 90°). The points are marked on the drawing as 0, 1, 

 2, 3, 4, and so forth. 



