NFLECTION OF LIGHT.

Ill

tinues to move on till it comes to the opposite surface; butthen instead of passing through, it bends and passes out again atthe same surface at which it entered; just as a ball would do ifmade to strike obliquely against a floor.

Experiment I.

Let a beam of solar light pass into a darkened room througha hole in the window-shutter ; at that part of the floor, wherethe beam of light falls, place a looking-glass, and then throwsome hair-powder into the air in order to render the beam oflight more visible:

We shall then see that the beam is reflected back into the air,and that the inclination of the reflected beam, is exactly the sameas that of the incidental one.

The common experiment of children casting the light of thesun, by means of a looking-glass, into various distant places,also illustrates this property.

5. INFLECTION OF LIGHT.

When a ray of light passes within a certain distance of a body,parallel to which it is moving, it is attracted, or bent towards it.This inflection is caused by an attractive power to which thelight is obedient.

Experiment I.

Admit a beam of light into a dark room, through a round holein the window-shutter and place at the spot on the floor whereit falls a sheet of paper, the rays of light will there form around luminous spot. But if we bring two pen-knives, withtheir edges towards each other, on opposite sides of the hole,and make them approach each other gradually, the luminousspot will dilate itself on the sides of the knives, indicating that