Can stars be seen in the daytime from a well?

The popular belief that stars’ and planets can be seen in the daytime from the bottom of a well or shaft is true only to a very limited extent. A person observing the stars in daylight is assisted .by a shaft or tube in two ways. The pupil of the eye is protected from stray light and lateral illumination. If transfused light can be cut off the acuteness of vision is considerably increased in the straight line of the tube. Thus it happens that occasionally an observer at-the bottom of a well, mine shaft, silo or canyon is able to see planets 6r bright stars at midday. It is commonly said that there are about twenty stars of the first magnitude that are bright enough to be detected by the unaided eye looking from the bottom of a well or pit. The Yerkes Observatory, however, is of the opinion that in most cases where stars and planets have been seen in this -manner they could have been seen without the assistance of a well or shaft, provided the eye had been protected from stray light. For several weeks every year the planet Venus can be seen at any hour of the day with the naked eye if the observer knows where to look. But it can be seen somewhat better if the observer stands in the shadow of a tree or a portico in order to reduce the diffuse light. The United States Naval Observatory is also of the opinion that there is little foundation for the popular notion that stars can be seen in the daytime from a deep shaft almost as well as they can be seen on a clear night.