From a convex surface, parallel rays when reflected are made to diverge; convergent rays are reflected less convergent; and divergent rays are rendered more divergent. It is the nature of all convex mirrors and surfaces to scatter or _disperse_ the rays of light, and in every instance to impede their convergence. The following figure shows the course of parallel rays as reflected from a convex mirror. AEB is the convex surface of the mirror; and KA, IE, LB, parallel rays falling upon it. These rays, when they strike the mirror, are made to diverge in the direction AG, BH, &c. and both the parallel and divergent rays are here represented as they appear in a dark chamber, when a convex mirror is presented to the solar rays. The dotted lines denote only the course or tendency of the reflected rays, towards the _virtual_ focus F, were they not intercepted by the mirror. This virtual focus is just equal to half the radius CE. [Illustration: _figure 19._] The following are some of the properties of convex mirrors: 1. The image appears always erect, and behind the reflecting surface. 2. _The image is always smaller than the object_, and the diminution is greater in proportion as the object is further from the mirror, but if the object touch the mirror, the image at the point of contact is of the same size as the object. 3. The image does not appear so far behind the reflecting surface as in a plain mirror. 4. The image of a straight object, placed either parallel or oblique to the mirror is seen _curved_ in the mirror; because the different points of the object are not all at an equal distance from the surface of the mirror. 5. Concave mirrors have a _real_ focus where an image is actually formed; but convex specula have only a _virtual_ focus, and this focus is behind the mirror; no image of any object being formed before it. The following are some of the purposes to which convex mirrors are applied. They are frequently employed by painters for reducing the proportions of the objects they wish to represent, as the images of objects diminish in proportion to the smallness of the radius of convexity, and to the distances of objects from the surface of the mirror. They form a fashionable part of modern furniture, as they exhibit a large company assembled in a room, with all the furniture it contains, in a very small compass, so that a large hall with all its objects, and even an extensive landscape, being reduced in size, may be seen from one point of view. They are likewise used as the small specula of those reflecting telescopes which are fitted up on the _Cassegrainian_ plan, and in the construction of Smith’s Reflecting Microscope. But on the whole, they are very little used in the construction of optical instruments. _Properties of Concave speculums._