lected ray b and the perpendicular line d is
called the angle of reflection, and these angles are always equal.

[Illustration: Fig. 2 (hipho_2.gif)]

It is by this reflection of light that objects are made visible; but
unless light falls directly upon the eye they are invisible, and are
not sensibly felt until after a certain series of operations upon the
various coverings and humors of the eye. Smooth and polished surfaces
reflect light most powerfully, and send to the eye the images of the
objects from which the light proceeded before reflection. Glass, which
is transparent--transmitting light--would be of no use to us as a
mirror, were it not first coated on one side with a metalic amalgam,
which interrupts the rays in their passage from the glass into the air,
and throws them either directly in the incident line, or in an oblique
direction. The reason why trees, rocks and animals are not all
mirrors, reflecting other forms instead of their own, is, that their
surfaces are uneven, and rays of light reflected from an uneven surface
are diffused in all directions.

Parallel rays falling obliquely upon a plane mirror are reflected
parallel; converging rays, with the same degree of convergence; and
diverging rays equally divergent.

Stand before a mirror and your image is formed therein, and appears to
be as far behind the glass as you are before it, making the angle of
reflection equal to that of incidence, as before stated. The incident
ray and the reflected ray form, together, what is called the passage of
reflection, and this will therefore make the actual distance of an
image to appear as far again from the eye as it really is. Any object
which reflects light is called a radiant. The point behind a
reflecting surface, from which they appear to diverge, is called the
virtual focus.

Rays of light being reflected at the same angle at which they fall upon
a mirror, two persons can stand in such a position that each can see
the image of the other without seeing his own. Again; you may see your
whole figure in a mirror half your length, but if you stand before one
a few inches shorter the whole cannot be reflected, as the incident ray
which passes from your feet into the mirror in the former case, will in
the latter fall under it. Images are always reversed in mirrors.

Convex mirrors reflect light from a rounded surface and disperse the
rays in every direction, causing parallel rays to diverge, diverging