A. Because the light of day is so much stronger, that it eclipses the feeble light of a glow-worm; in consequence of which, glow-worms are invisible by day.
Q. Why can we not see the stars in the day-time?
A. Because the light of day is so powerful, that it eclipses the feeble light of the stars: in consequence of which, they are invisible by day.
Q. Why can we see the stars even at mid-day, from the bottom of a deep well?
A. As the rays of the sun never come directly over a well, but the rays of the stars do; therefore the light from those stars (in such a situation) is more clear than the light of the sun.
Q. What is the use of two eyes, since they present only one image of any object?
A. The use of two eyes is to increase the light, or take in more rays of light from the object looked at, in order that it may appear more distinct.
Q. Why do we not see things double, with two eyes?
A. 1st—Because the axis of both eyes is turned to one object; and, therefore, the same impression is made on the ret´ina of each eye.