Oldal 108 [108]
OCR
CHAPTER III COLOURS IN STILL WATER Fig. 20. Refraction of a Fig. 21. Refraction of a ray of light on entering ray of light on emerging from water. water. as distinguished from that due to surface reflexion, we must trace the passage of light from air into water, and wice versd, from water into air. Suppose a beam of light AO (Fig. 20) to strike the surface of still water at O. A portion of the light will then be reflected “ regularly " (as explained in Chapter I) along OB and the remainder will enter the water. This second portion will not continue its course in a straight line to a, but will be
