A surveyor on one bank of canal observes the images of the 4-inch mark and 17-ft mark on a vertical staff, which is partially immersed in the water and held against the bank directly opposite to him. He see that the reflected and refracted rays come from the same point which is the center of the canal. If the 17-ft mark and the surveyor’* eye are both 6 ft above the water level, estimate the width of the canal, assuming that the refractive index of the water is 4/3. Zero mark is at the bottom of the canal.
