the fullest light. We, therefore, place the observer in the open air before we conduct him to the limits of a dark room.
394.
A person walking in sun-shine in a garden, or on any level path, may observe that his shadow only appears sharply defined next the foot on which he rests; farther from this point, especially round the head, it melts away into the bright ground. For as the sun-light proceeds not only from the middle of the sun, but also acts cross-wise from the two extremes of every diameter, an objective parallax takes place which produces a half-shadow on both sides of the object.
395.
If the person walking raises and spreads his hand, he distinctly sees in the shadow of each finger the diverging separation