Stranica 29 [29]
OCR
REFLEXIONS IN SMOOTH WATER 9 word “inverted ’ in speaking of an image is therefore used in a peculiar sense. Though the image is upside down, every point in it is vertically beneath the corresponding point in the object, and when viewed so as to appear in the upright position, right has become left, and left right. Thus it is sometimes and perhaps more correctly spoken of as a “ perverted " image. Such reflexion, giving rise to the formation of an image, is called regular. Inthe case of reflexion from a rough or unpolished object, the incident light (a part only of which is reflected) is very much scattered, as if the surface on which the light falls were made up of countless minute plane surfaces facing in every possible direction. The law of reflexion still holds good, but owing to the irregularity of the surface the eye receives light from all directions and the formation of an image is impossible. It is by means of this surface-scattering, or so-called “ zvregular reflexion " of light, that all objects which are not self-luminous become visible to us. The perfectly polished mirror, on the other hand, is invisible; we cannot distinguish its surface at all, and are only made aware of its existence by the images in it of neighbouring objects. We have shown how the image is an exact reproduction of the object. But the wzew we get of the image is a different one from our direct view of the object. In the language of perspective, the projection on to the picture-plane of the image differs from that of the object. In Fig. 3 the candlestick and its image are drawn in perspective instead of in section in order to show this difference, In the reflexion the under
