Let BDEC be the well, and DE the water.
The ray AB strikes against the brick-work inside the well; and
The ray AC strikes against the brick-work outside the well.
None will ever touch the water DE.
Q. Why do we see the moon reflected in a well very often?
A. As the rays of the moon are not so oblique as those of the sun, they will often reach the water. (See next figure.)
Q. Why are the stars reflected in a well, although the sun is not?
A. As the rays of the stars are not so oblique as those of the sun, they will often reach the water.
Here the moon's rays AB, AC, both strike the water DE, and are reflected by it.
Q. In a sheet of water at noon, the sun appears to shine upon only one spot, and all the rest of the water seems dark,—Why is this?