SPATIAL PROBLEMS IN GEOMETRICAL SEISMICS 



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as points of a ray having zero depth. For the ray under consideration this 

 point is marked on the plan (Fig. 10) by the letter d. After we have deter- 

 mined the points of emergence of all the rays and joined them by a smooth 

 line we obtain the geometrical position of the points of emergence of rays 

 belonging to one ray surface. The intersection trace of the ray surface mth 

 the observation plane is shown by the line 6. 



We have now consistently traced in space a ray surface (which in the 

 first medium was conic) formed by rays emerging from a source at an angle 

 of 30° with the vertical, and we have obtained for each of the rays under 

 consideration its projection onto the observation plane. The other ray sur- 



270 



Fig. 15. Determination of direction of rays refracted on plane iaclined interface on 



transition, from second medium to first (the constructions were made for a 30° ray 



surface). 1 — directions of incident rays having azimuths from to 360° at every 10°; 



2 — directions of refracted rays; 3 — direction of normal to interface. 



